Annual Report 2014 2 Contents

Contents

3 Flashback to 2014

7 Facts & Figures

Research Area 1 Functional Quantum Materials 9 1.1 Exotic ground states and low-energy excitations in bulk systems 13 1.2 Unconventional superconductivity: Mechanisms, materials & applications 17 1.3 Magnetic materials for energy 23 1.4 Engineering magnetic microtextures 28 1.5 Topological states of matter

Research Area 2 Function through Size 31 2.1 Non-equilibrium phases and materials 35 2.2 Intelligent hybrid structures 39 2.3 Multifunctional inorganic nanomembranes 43 2.4 Nanoscale magnets 47 2.5 Materials for energy efficiency, storage & conversion

Research Area 3 Quantum Effects at the Nanoscale 51 3.1 Designed interfaces and heterostructures 55 3.2 Self-organised electronic order at the nanoscale 59 3.3 Quantum and nano-photonics 63 3.4 Functional molecular nanostructures and interfaces

Research Area 4 Towards Products 67 4.1 Surface acoustic waves: Concepts, materials & applications 71 4.2 Materials for biomedical applications 75 4.3 High strength materials Leibniz Application Laboratory Amorphous Metals 79 4.5 Concepts and materials for superconducting applications

Appendix 83 Publications 104 Patents 106 PhD and diploma/master theses 108 Calls and awards 109 Scientific conferences and IFW colloquia 110 Guests and scholarships 113 Guest stays of IFW members at other institutes 115 Board of Trustees, Scientific Advisory Board 116 Research organization of IFW Dresden Organization chart of the IFW Dresden Flashback to 2014 3

Flashback to 2014

2014 was a crucial year for the Leibniz Institute for Solid State and Materials Research Dresden (IFW): We underwent a serious evaluation procedure, had a change in the scientifi c management at the same time, started a new research program with a complete new structure and paved the way for a new director of one of the five IFW institutes.

The most important event was the evaluation of the Institute by the Senate of the Leib- niz Association. All Leibniz Institutes are institutionally funded by the federal government and by the German Länder in equal shares. The justification of this funding has to be affirmed for each institute in intervals of seven years by an evaluation panel set up by the senate commission of the Leibniz Association. The prerequisite of confirmed funding is high quality scientific work and its high relevance for the whole society. A panel of renowned, international scientists visited the institute for two days in July 2014. The whole institute prepared very carefully for this third evaluation since the foundation of IFW. We look quite optimistically forward to the final report that will be published by the Leibniz Association Senate in spring 2015.

Immediately before the evaluation visit Prof. Dr. Manfred Hennecke has been appointed as temporary Scientific Director of IFW. Having been the President of Federal Insti- tute for Materials Research and Testing (BAM) for 11 years he retired in 2013. He returned from retirement to fill the position of the Scientific Director of IFW which was vacant due to the request of Prof. Dr. Jürgen Eckert to be released from this office and to revert to his role as the director of one of the five IFW institutes. One of the main task of Professo r Hennecke is to push changes in the management structure of IFW in a way that enables for long-term stability.

Further personnel changes in the Institute’s management concern the directorship of one of the five IFW’s institutes: the Institute for Metallic Materials which was headed by Prof. Dr. Ludwig Schultz up to the end of September 2014. The successor in this position is about to being appointed which will have new impact on the research program of the whole IFW. 4 Flashback to 2014

Scientifically, 2014 was a very productive year for IFW. The appendix gives a complete Inauguration ceremony of the new annex building of IFW in February 2014 record of the publications, invited talks, patent applications, completed graduations and theses, academic events, and guest stays. In the main part of this Annual Report outstanding scientific results are presented according to the new structure of the IFW’s research program which is organized into four large research areas. ½ Research Area 1: Functional quantum materials ½ Research Area 2: Function through size ½ Research Area 3: Quantum effects at the nanoscale ½ Research Area 4: Towards products

A new aspect of this program is that it consists of Research Topics that are interdisciplinary and bring closely together researchers from different IFW institutes. The creation of such additional synergy, which strengthens the collaboration within the IFW, is one of the main goals of this new program. In addition, the new project-oriented research structure allows for a considerable amount of flexibility in particular for the subtopics and will provide a dynamical framework for developing, nurturing and consolidating our future research lines. While being distinctly multidisciplinary, there is a clear common aspect to all activities of the IFW Dresden: all researchers at the IFW Dresden investigate yet unexplored properties of novel materials with the aim to establish new functionalities and applications. The range of materials that are investigated in this context is broad but well-defined. It contains Quantum Materials, a highly topical class of materials in condensed matter physics as well as Functional Materials, representing an important part of modern materials engineering. In the last years Nanoscale Materials, which are a strong focus of present day materials science and a crucial material class for cutting-edge developments in electrical engineering, came in the fore of our research in several IFW institutes. These three classes, Quantum Materials, Functional Materials and Nanoscale Materials, provide the three materials-oriented pillars of the IFW. Each of these three new research areas, connecting two different classes of materials, follows the motto of the Leibniz Association “theoria cum praxi”: They consist of well-defined research topics connecting basic science with applied research and bring together researchers from all five IFW institutes. The research area “Towards products” binds together materials science and engineering that is at the borderline to prototypes or products. Establish- ing, fostering and promoting the contact to industry partners is the main aspect within this activity. Flashback to 2014 5

Prizes and Awards for IFW members: As a Leibniz Institute the IFW is budgeted by the federal government and the German Tschirnhaus Medal for the best PhD theses (left), federa l states in equal parts. However, a considerable extension of capability is the IFW Research Prize for Dr. Sabind Wurmehl (middle), Prize of the German Copper Institute for amount of third party project funding which is also an important index of quality. The Dr. Alexander Kauffmann (right) level of third party funding in 2014 amounts to 11.874 Mio. Euro – a level at the forefront of the Leibniz Association. Most of this project funding was acquired in a highly com - petitive mode from the DFG and the EU. In particular the grant of the new Collaborative Research Centre 1143 on “Correlated magnetism: From frustration to topology” where the IFW is collaborating with the TU Dresden shows the competitive capability of the IFW. Among the large number of third party funded projects are three DFG-Priority Programs that are coordinated by the IFW, further eight DFG-Priority Programs where the IFW participates, as well as three DFG Research Groups where the IFW participates. As in the previous years the IFW has been very successful in initiating EU projects and participat- ing in them. Though quite time consuming these project applications have very positive effects on networking the IFW with other European groups. 9 of our 16 EU projects run- ning in 2014 have been coordinated by the IFW.

Essentially publicly funded, the IFW is obliged to make its research results public. About 380 publications in scientific journals and conference proceedings report on the IFW’s research results on the year 2014. In almost 200 invited talks the Institute’s scientists presented their work at other places around the world. 19 patents were issued for the IFW, and applications for 16 more patents have been made. Apart from these scientific communications the IFW continued its large efforts to make scientific work accessible for the general public and to inspire young people to study science or engineering. The IFW took part in many joint actions like the lecture series “Physics on Saturday”, “Junior Doctor” or the Summer University of the TU Dresden. Besides these big events we organize almost weekly lab-tours for various visitor groups, from school classes through official representatives to guests from foreign organizations. Especially the IFW’s superconducting test facility SpuraTrans in Dresden-Niedersedlitz has proved very popular among visitors, be it representatives from companies, students groups or politicians.

With respect to the infrastructural development we have put large efforts during the last years into the realization of a new annex building with special laboratory areas and additional office space. In beginning of 2014 construction works were completed and we celebrated the inauguration of the annex building. Right in between the old and the new parts of the building a nice atrium was created which already have proved very useful for various events. 6 Flashback to 2014

2014 was again a yielding year with respect to prizes and honors awarded to members Active in scientific communication on conferences, workshops and fairs. of the IFW. Among them are the International Dresden Barkhausen Award for Prof. Dr. Oliver G. Schmidt and the DGM Prize for Prof. Dr. Jürgen Eckert. Dr.-Ing. Alexander Kauff- mann was awarded two prizes for his outstanding PhD thesis: the DGM Junior Award and the Prize of the German Copper Institute. The most prominent prize for an IFW member surely was the German Federal Cross of Merit (first class) for Prof. Dr. Manfred Hennecke, although it was not related to his activities at our Institute. A full list of prizes awarded to members of the IFW is included in the appendix.

Furthermore, three scientists of the IFW have been offered a chair at universities in 2014: Dr. Maria Daghofer accepted a call to the University of Stuttgart and Prof. Dr. Jürgen Eckert is negotiating with University Leoben (Austria) and Dr. Jochen Geck with the University of Salzburg (Austria).

A crucial part of the IFW’s identity is its vivid life including the cultivation of the scientific dialogue, family-friendly working conditions, intercultural diversity and the support of sportive and cultural activities. In 2014 the IFW organized a series of workshops, colloqui a and talks to foster the scientific dialogue and, along the way, allow for social and communication aspects of cooperation. An important meeting for all scientists of the IFW was the two-day program meeting where all scientists discussed and adjusted the research program for the following year. Social events like the annual IFW Summer Day, the Christmas party and vernissages to our art exhibitions also contribute to a good working atmosphere among all IFW groups.

The positive development of the IFW is being fostered continuously by the engagement of colleagues and partners from universities, research institutes and industry, our Scientific Advisory Board and the Board of Trustees as well as the funding organizations. This holds true especially when the institute experiences turbulent times. We would like to thank all our partners and friends for their support and cooperation. Facts & Figures 7

Facts & Figures

Organization The Leibniz Institute for Solid State and Material Research Dresden (IFW) is one of currentl y 89 institutes of the Leibniz Association in Germany. It is a legally independent association, headed by the Scientific Director, Prof. Dr. Manfred Hennecke, and the Administrativ e Director, Hon.-Prof. Dr. h. c. Rolf Pfrengle.

The scientific body of the IFW Dresden is structured into five institutes, the directors of which are simultaneously full professors at Dresden, respectively Chemnitz Universities of Technology: ½ Institute for Solid State Research, Prof. Dr. Bernd Büchner ½ Institute for Metallic Materials, Prof. Dr. Rudolf Schäfer (temporarily) ½ Institute for Complex Materials, Prof. Dr. Jürgen Eckert ½ Institute for Integrative Nanosciences, Prof. Dr. Oliver G. Schmidt ½ Institute for Theoretical Solid State Physics, Prof. Dr. Jeroen van den Brink Further divisions are the Research Technology Division and the Administrative Division.

Financing The IFW receives an institutional funding of 50% from the Federal Government of Ger- many and the Länder Governments each. In 2014, this funding was about 30,587 million euros. In addition, there was a total of third party funding in 2014 of about 11,874 million euros. From that, about 37% were funded by the DFG, 31% by EU projects, 12% by Federal Government projects, 10% by industry projects and 10% by other projects and projects funded by the Free State of Saxony. 8 Facts & Figures

Personnel On December 31, 2014, 506 staff members were employed at the IFW, including 114 doctorate students and in addition 22 apprentices in seven different vocational trainings. Furthermore, there was a total of 145 guest scientists and 15 diploma students working at the IFW in 2014.

Gender equality, as well as work life balance, are defined goals of the IFW Dresden. In 2014, the percentage of women in scientific positions was 34% and the percentage of women in scientific leading positions was 31%. In 2007, the IFW qualified for the certificat e “audit berufundfamilie” (a strategic management tool for a better com - patibility of family and career) and was already re-audited two more times.

Vocational training has always been an important activity of the IFW. At present, appren- ticeships are available for seven professions. On annual average, around 25 trainees complete an apprenticeship at the IFW. In 2014, the IFW was awarded the prize “Excellent Training Company” by the German Chambers of Commerce and Industry and the institute’s apprentices received awards for their excellent performance during their training. A female physics lab technician apprentice was even nominated for the Apprenticeship Price 2014 of the Leibniz Association and achieved second place in the end. From 2012 until 2014, the IFW’s Administrative Director was the Executive Board Representative of the Dual Vocational Education and Training of the Leibniz Association.

Number of publications and patents In terms of publications, the qualitative and quantitative level remains high at the IFW. In 2014, there were altogether 336 publications quoted by Web of science. By Decem- ber 31, 2014, the IFW holds 143 patents in Germany and 155 international patents. Research Area 1 FUNCTIONAL QUANTUM MATERIALS 9

Research Topic 1.1 Exotic Ground States and low-energy excitation in bulk systems People: M. Abdel-Hafiez, A. Alfonsov, S.-H. Baek, S. Bahr, M. Belesi, V. Bisogni, E. M. Brüning, M. Daghofer, T. Dey, S.-L. Drechsler, J. Geck, H. J. Grafe, F. Hammerath, C. Hess, N. Hlubek, L. Hozoi, H. Kandpal, V. Kataev, V. M. Katukuri, S. Kourtis, R. Kraus, A. O. Leonov, A. Maljuk, A. Mohan, S. Nishimoto, J. Romhanyi, U. K. Rössler, K. Roszeitis, I. Rousochatzakis, M. Schäpers, W. Schottenhamel, C. Sekar, H. Stummer, Y. Utz, A. Wolter, S. Wurmehl Responsible Directors: B. Büchner, J. van den Brink

Summary: In this research topic we investigate both experimentally and theoretically a broad class of complex transition metal oxides such as cuprates, cobaltites, iridates and pyrochlore compounds, where quantum spin fluctuations, strong magnetic frustration effects and spin-orbit coupling give rise to unconventional quantum ground states and exotic spin excitations. Our research benefits a lot from a unique combi - nation of different, mutually complementary methods that is available at the IFW Dresde n, including expertise in both theory and experiment. In this article we review our work in 2014, which enabled us to obtain a number of interesting new fundamental insights into the magnetism of correlated quantum matter.

Complex transition metal (TM) oxides provide a rich playground for studies of fundamental models of quantum magnetism. In particular, in certain crystal lattices chemical bonds mediate strong magnetic exchange coupling between the spins of TM ions only in one (1D) or two (2D) spatial directions giving rise to low-dimensional spin networks in form of chains, ladders and planes. The spin chains in the 3d cuprates are considered as almost ideal realizations of the celebrated 1D spin-1/2 isotropic Heisenberg antiferromagnetic model (HAFM), since the Cu2+ ion carries a small quantum spin-1/2 and the orbital momentum is quenched.

One focus of our research has been on the elementary excitations of a quantum spin-1/2 chain, the spinons. In our combined theoretical and experimental approach, taking spin-

on excitations in the quantum antiferromagnet CaCu2O3 as an example, we demonstrate that femtosecond dynamics of magnetic electronic excitations can be probed by direct resonant inelastic x-ray scattering (RIXS) [1]. To this end, we isolate the contributions of single and double spin-flip excitations in experimental RIXS spectra, identify the 10 Research Area 1 FUNCTIONAL QUANTUM MATERIALS

Fig. 1: (a) Initial state, just before the creation of the core hole. (b) Intermediate state with one doublon and one core-hole present right after the creation of the core hole. As the 3d level at the core-hole site has a net spin of 0, the magnetic coupling to neighboring sites vanishes. (c) Intermediate state just before the de-excitation of the core-hole. Left: two spins next to the core-hole site have flipped due to scattering on the doubly occupied site. Right: the spin-orbit coupling of the 2p state has flipped the core-hole spin. (d) Two-spinon excitations with ΔS = 0 (left) and ΔS =1 (right) present in the final state.

physica l mechanisms that cause them, and determine their respective time scales (Fig.1). By comparing theory and experiment, we find that double spin flips need a finite amount of time to be generated, rendering them sensitive to the core-hole lifetime, whereas single spin flips are, to a very good approximation, independent of it. This shows that RIXS can grant access to time-domain dynamics of excitations and illustrates how RIXS experiments can distinguish between excitations in correlated electron systems based on their different time dependence.

In the 1D spin-1/2 HAFM the spinons can be excited by an infinitesimally small energy, i.e., excitations are gapless. However, perturbations of the spin chain, such as modulation of the exchange coupling along the chain, may radically alter the spin excitation spectrum. We have shown this experimentally by measuring the longitudinal 63Cu nuclear -1 spin relaxation rate T1 in the model spin-1/2 chain cuprate Sr1.9Ca0.1CuO3 [2]. Owing to the on-site hyperfine coupling, the nuclear spin sensitively probes the Cu electron spin -1 dynamics. We observe a surprising exponential drop of the rate T1 below ∼ 100 K which signals an opening of a pseudogap in the spin excitation spectrum, i.e., a substantial suppression of spinon excitations at low energies (Fig. 2). We attribute this drastic effect to the off-chain partial substitution of Sr by Ca which causes Cu-O bond disorder and consequently a small random alteration of the intrachain exchange coupling. Furthermore, we can show that such bond disorder has a strong impact on the propa - gation of the spinons along the chain. By measuring the magnetic heat conductivity in single crystals of (Sr1-xCax)2CuO3 we have found that the spinon mean-free path is very sensitive to even slight bond disorder and reduces from >1300 lattice spacings in the clean material (x = 0) to very short ∼12 lattice spacings for large Ca dopings [3].

Frustration effects arising in the 1D spin-1/2 HAFM due to AFM next-nearest neighbor interactions have been studied for the Cu chains in linarite PbCuSO4(OH)2. Indeed we observed unusual magnetically ordered states such as helical structures together with a rich phase diagram along the Cu chain direction [4,5]. Using DMRG and TMRG approaches we demonstrated that a significant symmetric anisotropic exchange is necessary to account for the basic experimental observations, which in turn might stabilize a triatic (three- magnon) multipolar phase [4]. Research Area 1 FUNCTIONAL QUANTUM MATERIALS 11

63 -1 Fig. 2: The Cu nuclear relaxation rate T1 decreases strongly below ~100 K due to the opening of a pseudogap in the spin excitation spectrum of Sr1.9Ca 0.1CuO3. Squares and closed circles correspond to measurements along the crystallographic b- and a-axis, respectively, and open circles denote our earlier data on the spin-chain compound Sr0.9Ca0.1O2 shown here for comparison [see, F. Hammerath et al., Phys. Rev. Lett. 107, 017203 (2011)]. The inset shows the temperature evolution of the stretching exponent γ of the nuclear magnetization decay.

Though long-range magnetic order in 1D spin-1/2 HAFM’s is not possible even at T = 0 due to quantum fluctuations, in real materials residual interchain couplings often induce magnetic order at finite temperatures. We have examined one specific case of the competin g interchain couplings corresponding to the so-called Nersesyan-Tsvelik

model in the spin-1/2 chain compound (NO)[Cu(NO3)3] [6]. Interestingly, our specific heat, neutron scattering and muon spin rotation data reveal that frustration of the in-

terchain exchange yields incommensurate magnetic order at TN = 0.58 K, much smaller than the intrachain exchange J ∼ 140 K. A somewhat similar effect of frustration, also yielding a suppressed and incommensurate magnetic order, we have found by measuring nuclear magnetic resonance in a system with larger spin value and dimensionality,

namely the non-olivine LiCoPO4 [7].

The nature and the role of longer-range exchange couplings has been also explored by joint high-field electron spin resonance (HF-ESR) measurements and theoretical analy-

sis in the 3D Cu oxide compound Cu2OSeO3 [8,9], a Mott insulator recently shown to har- bor skyrmion physics. An effective model of coupled ferrimagnetic Cu tetrahedra has been derived by using exchange couplings obtained from electronic-structure computations and modeling of the HF-ESR data. It has allowed us to calculate the fundamental magnetic properties of this complex ferrimagnet, including the pitch length of the Dzyaloshinskii spiral ground state, in very good agreement with recent experiments. Ad- ditionally, a number of new predictions have been made [8]. In particular, the effective sublattices of Cu tetrahedra should display weak AF canting within each unit cell; near the ordering temperature, the magnetic phase diagram will embody a skyrmionic phase as condensates of partial skyrmions with defects in zero or low magnetic fields and a densely packed array of integer skyrmions stratified by larger applied fields.

Besides 3d TM oxides, recently the 5d iridates have attracted considerable attention due to predictions of novel magnetic phenomena driven by strong spin-orbit coupling. In particular, the orbital momentum of Ir 4+ is unquenched, which should lead to strongly anisotropic magnetic interactions. By HF-ESR we have studied the low-energy spin

dynamics in a single crystal of Sr2IrO4, the prototype 2D spin-orbital Mott insulator. By measuring the frequency dependence of the AF resonance modes we have found a sur- prisingly small energy gap for magnetic excitations, amounting to only 0.83 meV [10]. 12 Research Area 1 FUNCTIONAL QUANTUM MATERIALS

This suggests rather isotropic Heisenberg dynamics of the interacting Ir4+ effective spins, despite the spin-orbital entanglement in the ground state. The anomalous order of the Ir t2g levels in Sr2IrO4, evidenced by the structure of the g tensor [10], is confirmed by electronic-structure calculations [11] and apparently related to low-symmetry potentials involving atomic sites beyond the nearest-neighbor O cage. The sizable Ir t2g splitting s are also reflected in RIXS, e.g., in the two-peak structure of the j = 3/2-like spin-orbital exciton. By a detailed analysis, we have further shown that this charge- neutral excitation is dressed with magnons and propagates with the canonical characteristics of a quasiparticle that mirrors the one-hole propagation in the spin-1/2 background of 2D cuprate superconductors [12]. Valuable insights into the precise structure and the magnitude of the magnetic couplings, both isotropic and anisotropic, comes from many-body quantum chemistry calculations – while in the 2D square-lattice 5d 5 iridate

Ba2IrO4 a Heisenberg-compass type of model is realized [13], the dominant interaction in 2D honeycomb systems such as Na2IrO3 is the Kitaev exchange, which further turns out to be ferromagnetic from the ab intio computations [14]. Joint RIXS measurements and theoretical investigations have also allowed to clarify the evolution of the mag - netic excitation spectrum of Sr2IrO4 as function of strain [15].

Regarding the material synthesis and crystal growth, where we apply different methods ranging from flux methods (e.g., for iridates) and high pressure synthesis in the GPa regime to the travelling solvent floating zone using optical heating, we have succeeded to grow high quality single crystals of LaCuO2 [16] and Li(Mn,Ni)PO4 [17] which are now available for magnetic studies within this research topic.

[1] V. Bisogni et al., Phys. Rev. Lett. 112, 147401 (2014) [2] F. Hammerath et al., Phys. Rev. B 89, 184410 (2014) [3] A. Mohan et al., Phys. Rev. B 89, 104302 (2014) [4] M. Schäpers et al., Phys. Rev. B 88, 184410 (Nov. 2013) [5] M. Schäpers et al., Phys. Rev. B 90, 224417 (2014) [6] C. Balz et al., Phys. Rev. B 90, 060409(R) (2014) [7] S.-H. Baek et al., Phys. Rev. B 89, 134424 (2014) [8] O. Janson et al., Nature Commun. 5, 5376 (2014) [9] M. Ozerov et al., Phys. Rev. Lett. 113, 157205 (2014) [10] S. Bahr et al., Phys. Rev. B 89, 180401(R) (2014) [11] V. M. Katukuri et al., Inorg. Chem. 53, 4833 (2014) [12] J. Kim et al., Nature Commun. 5, 4453 (2014) [13] V. M. Katukuri et al., Phys. Rev. X 4, 021051 (2014) [14] V. M. Katukuri et al., New. J. Phys. 16, 013056 (2014) [15] A. Lupascu et al., Phys. Rev. Lett. 112, 147201 (2014) [16] A. Mohan et al., J. Cryst. Growth 402, 304 (2014) [17] K. Wang et al., J. Cryst. Growth 386, 16 (2014).

Funding: DFG

Cooperation: MPI-CPfS Dresden, MPI-PKS Dresden, TU Dresden, Helmholtz-Zentrum Dresden-Rossendorf, MPI-FKF Stuttgart, Helmholz-Zentrum Berlin, University Heidelberg, TU Berlin, TU Braunschweig, University Magdeburg, ILL Grenoble, ANSTO Australia, University Paris-Sud, University Pavia, University Tokyo, Argonne National Laboratory, PSI Villigen, ISIS, Politecnico di Milano, Moscow State University, University of Toronto, University of California Irvine, University of Crete, IISER, Pune, India Research Area 1 FUNCTIONAL QUANTUM MATERIALS 13

Research Topic 1.2 Unconventional superconductivity: Mechanisms, materials & applications People: S. Aswartham, S.-H. Baek, D. Baumann, R. Beck, S. Borisenko, Dai-Ning Cho, S. L. Drechsler, D. Efremov, D. Evtushinsky, G. Fuchs, R. Ganesh, J. Geck, M. Gillig, A. Wolter-Giraud, H. J. Grafe, V. Grinenko, D. Gruner, M. Abdel Hafiez, L. Harnagea, C. Hess, B. Holzapfel, R. Hühne, K. Iida, R. Kappenberger, S. Khim, K. Koepernik, T. Kühne, M. Kumar, F. Kurth, Zhonghao Liu, S. Luther, I. Morozov, P. K. Nag, K. Nenkov, S. Richter, M. Scheffler, W. Schottenhamel, M. Schulze, S. J. Singh, F. Steckel, S. Sykora, J. Trinckauf, S. Wurmehl, C. Wuttke, F. Yuan Responsible Directors: B. Büchner, L. Schultz, J. van den Brink

Summary: Superconductivity as a quantum phenomenon represents one of the most fundamental problems of condensed matter physics. In spite of the long history of research there are still many new findings and open questions. Nowadays the so called unconventional superconductors are in the focus of the condensed matter commu- nity, since these materials demonstrate the highest superconducting critical temperature. In order to improve application and to find new compounds, we try to understand the nature and the key features of the emergent superconductors by means of systematic studies, both experimental and theoretical.

The following specific aspects of unconventional superconductivity are at the focus of our research: ½ Symmetry and structure of the superconducting and competing order parameters ½ Nature of the pairing mediator ½ Competing/coexisting ground states, quantum criticality ½ Pseudogap, various density waves, nematic order ½ Disorder induced effects

Our research efforts seek to obtain systematic and quantitative information by applying modern experimental methods supplemented by subsequent theoretical treatment. To obtain the most precise information we use several complementary experimental techniques for the same samples. More specifically, in the experiments we use spatially and momentum resolved spectroscopies, thermodynamics, transport, magnetic resonance 14 Research Area 1 FUNCTIONAL QUANTUM MATERIALS

as well as phase-sensitive techniques applied together to the wide range of the single- crystalline bulk and in-situ grown thin film and heterostructured materials, such as iron-based pnictides and chalcogenides, cuprates, heavy fermion systems, ruthenates, and elemental superconductors. In theory we use a set of techniques to describe the electronic structure of superconducting materials among which are various types of Renormalization Group methods, diagramatic Green function methods, multiband Eliash- berg theory and Density Functional Theory.

Our current work on the nematic order in FeSe [1] may illustrate the field of our research. It concerns one of the important aspects of all unconventional superconductors: in these materials superconductivity emerges in the vicinity to other instabilities. Therefore the understanding which of the degrees of freedom, spin, orbital or lattice, drives these instabilitie s, gives the answer what is the glue of superconducting cooper pairing. Most of the parent compounds of the novel iron-based superconductors exhibit magnetic spin-densit y wave ordering as a ground state. But the magnetic transition is preceded or coincides with the tetragonal to orthorhombic structural transition. The state in betwee n these two transitions, which is characterized by a broken C4 symmetry while time-reversal symmetry is still preserved, is called nematic.

Previously, good arguments have been put forth which rule out lattice distortions as a driving mechanism for the structural transition. Therefore it was proposed that strong spin fluctuations may lead to the nematic order. Moreover there is experimental evidence of an increase of 1/(T1T ) in NMR experiments near the structural transition. However, the closeness of the two transitions (structural and magnetic) impeded an unambiguous answer to the question which degree of freedom is responsible for the structural transition.

FeSe is a unique material in that it shows only a structural but no magnetic transition and hence lends itself to the investigation of the genuine nematic phase. In FeSe, a tetragonal to orthorhombic symmetry reduction occurs at Tnem = 91 K, which is to be connecte d with a nematic instability. We measured NMR spectra of 77Se, having nuclear spin 1/2, as a function of temperature in an external magnetic field H = 9 T.

77 Below Tnem we observe a splitting of the Se lines for H||a into two lines l1 and l2 in contrast to the absence of a splitting for the H||c line l3, which hints to an in-plane symmetry change as shown in Fig.1a depicting the temperature dependence of the Knight shift K. Now we discuss the possible origin of the splitting. It can be excluded that the orthorhombic lattice distortions cause the line splitting K1-K2 due to a significant change of this splitting when the superconducting state is entered at Tc = 9.3K, where the lattice structure does not change notably. The in-plane orthorhombic distortion is much smaller than the a,c structural anisotropy of the layered lattice structure, while the size of K1 -K2 below Tnem is of comparable size to the line splitting K3 -K1,2 above Tnem. This is incompatible with the orthorhombic distortion being the origin of the large splitting K1 -K2. The averaged K1 and K2 signal has the same temperature dependence as K3 over the whole temperature range, while the difference Knight shift splitting

ΔK||a =(K2 -K1)/2 between l1 and l2 exhibits a typical √(Tnem -T ) temperature behavior of a Landau-type order parameter close to a second-order phase transition. In order to exclude spin degrees of freedom as cause of the observed in-plane line splitting we measured the spin-lattice relaxation rate as a function of temperature. The quantity

1/(T1T ) probes the dynamical susceptibility and hence the antiferromagnetic spin fluctuations. However crossing the nematic phase transition it barely changes, indicating no enhancement of spin fluctuation and putting the system far away from a magnetic instability. Only when approaching the superconducting transition we find a significant Research Area 1 FUNCTIONAL QUANTUM MATERIALS 15

(a) (b)

(c)

Fig. 1: Emergence of orbital-driven nematic state in FeSe. a, Temperature dependence of the 77 Se Knight shift K for fields ||a and ||c. Whereas at Tnem, K||a splits into lines l1 and l2, both K||c

and the averaged position of l1 and l2, show a smooth T-dependence. b, Temperature depend-

ence of the l1 -l2 line splitting below Tnem in terms of the difference ΔK||a. Inset: below Tnem the

splitting is proportional to √(Tnem -T ), as expected for an order parameter at a second-order phase transition. c, Top view of the FOO in FeSe with two different domains that are present in a twinned crystal. The double headed arrow indicates the nematic order parameter.

enhancement, which is evidence that spin fluctuations are not driving the nematic

transition. Furthermore, the extremely narrow NRM lines well below Tc indicate the complete absence of static magnetism.

This leaves orbital degrees of freedom and in particular ferro-orbital order (FOO) as driver for the nematic transition. Theoretical analysis of the free energy in the vicinity of the ferro-orbital ordering transition in the presence of a magnetic field allows to derive a direct proportionality of the order parameter ψ to the anisotropy in the mag-

netic susceptibility χ xx - χ yy ∝ ψ ∝ √(TOO -T ). An analysis of the hyperfine constants establishes that its anisotropy and hence the anisotropy of the Knight shift difference

are proportional to the orbital order parameter ψ: ΔK||a ∝√(TOO -T ) while the averaged in-plane and the out-of-plane Knight shift depend on ψ only in higher order. Clearly

the measured splitting ΔK||a shows a square root behavior close to the nematic transi-

tion (Fig. 1b), so that we conclude Tnem =TOO. NMR does not give information about the

orientation of the Fe 3dyz and 3dxz orbitals with respect to the in-plane lattice vectors a and b. However, the orthorhombic distortion induced by the FOO ordering implies an alignment of the main axis of χ with the lattice vectors: x||a and y||b, which leads to an FOO pattern aligned along either of the two in-plane axis depending on the actual domain in our twinned crystal (Fig. 1c). 16 Research Area 1 FUNCTIONAL QUANTUM MATERIALS

The resulting inequivalence of the a and b directions then naturally leads to the observed line splitting. A measurement of the NMR signal with the magnetic field along the [110] direction indeed does not lead to a splitting between l1 and l2 in the orthorhombic state below Tnem, which is another clear prove that the tetragonal symmetry is broken below

Tnem. Finally, the significant change of the Knight shift splitting ΔK||a below TC indicates that superconductivity and nematicy are competing orders - superconductivity tends to suppress orbital ordering and vice versa.

For a more complete overview of our research during 2014 we refer the reader to our published articles, a selection of which is given in the Reference Section.

[1] S-H. Baek et al. Nature Materials (2014), doi:10.1038/nmat4138. [2] K. Iida et al., APL 105, 172602 (2014). [3] D. Daghero et al., Applied Surface Science 312, 23 (2014). [4] R. Sobota et al., Applied Surface Science 312, 182–187 (2014). [5] R. Ganesh et al., Phys. Rev. Lett. 113, 177001(2014). [6] V. Grinenko et al., Phys. Rev. B 89, 060504(R) (2014). [7] A. Reifenberger et al., J. Low Temp. Phys., 175, 755 (2014). [8] V. Grinenko et al., Phys. Rev. B 90, 094511 (2014). [9] Yu.G. Naidyuk et al., Phys. Rev. B 89, 104512 (2014). [10] M.M. Korshunov et al., Phys. Rev. B 90, 134517 (2014). [11] S. Johnston et al., Phys. Rev. B 89, 134507 (2014). [12] H.-J. Grafe et al., Phys. Rev. B 90, 094519 (2014). [13] S. Ziemak et al., Supercond. Sci. Technol. 28, 014004 (2015). [14] F. Ahn et al., Phys. Rev. B 89, 144513 (2014). [15] D. V. Evtushinsky et al., Phys. Rev. B 89, 064514 (2014). [16] T. Saito et al., Phys. Rev. B 90, 035102 (2014). [17] E. Stilp et al., Sci. Reports 4, 6250 (2014). [18] J. Maletz et al., PRB 89, 220506 (R) (2014).

Funding: DFG (SPP1458, GRK1621), BMBF (ERA.Net Rus project), EU (SuperIron, IronSea)

Cooperation: Moscow state university; Pohang University, Korea; CNRS CRISMAT; IISER, Pune; University of Cologne; Helmholtz-Zentrum Berlin; University of Heidel- berg; University of Erlangen-Nürnberg; University of Greifswald; Goethe University, Frankfurt am Main; WMI Munich; TU Dresden; PSI, Switzerland; University of Pavia, Italy; Universit’a degli Studi dell’Aquila, Italy; University of California, Davis; University of British Columbia, Vancouver, Canada; Max Planck Institute for Solid State Physics, Stuttgart; University of Twente, Netherlands; B. Verkin Institute for Low Temperature Physics and Engineering, Kharkiv, Ukraine; Technical University Graz, Austria; Max-Planck Institute for Chemical Physics of Solids, Dresden; Kirensky Insti- tute of Physics, Krasnoyarsk, Russia; Çukurova University, Turkey; CNR-SPIN Genoa, Italy; University Nagoya, Japan; NHMFL Tallahassee, USA; Helmholtz-Zentrum Dresden-Rossendorf, Germany Research Area 1 FUNCTIONAL QUANTUM MATERIALS 17

Research Topic 1.3 Magnetic materials for energy People: V. Alexandrakis4, A. Backen, A. Bauer1, C. G. F. Blum, A. Edström7, S. Fähler, P. Fajfar9, C. Favero10, A. Funk, G. Giannopoulos6, S. Gottlieb-Schönmeyer1, T. Gottschall8, O. Gutfleisch8, Ch. Haberstroh16, S. Hamann4, O. Heczko3, R. Heller5, R. Hermann, C. Hess, M. Hoffmann, G. Hrkac14, A. Kato15, S. Kauffmann-Weiss, A. Kitanovski9, M. Kohl12, J. Kopecek3, M. Kopte, M. Krautz, B. Krevet12, J. Kuneš 3, D. Lindackers, A. Ludwig4, L. Manosa11, M. Meven2, O. Mityashkin, J. D. Moore, V. Neu, D. Niarchos6, R. Niemann, S. Oswald, B. Pedersen2, C. Pfleiderer1, A. Planes11, A. Poredoš 9, D. Pohl, B. Pulko9, Q.M. Ramasse13, A. Regnat1, L. Reichel, M. Richter, S. Rodan, J. Romberg, J. Rusz7, S. Sawatzki8, M. Schmitt12, T. Shoji15, A. Siegel4, K.P. Skokov8, F. Steckel, J. Tušek9, E. Vives11, A. Waske, B. Weise, T. G. Woodcock, S. Wurmehl, M. Yano15 Responsible Directors: B. Büchner, J. Eckert, L. Schultz, J. van den Brink

Summary: Our investigations on magnetic materials for energy-related applications are illustrated by several examples, which span the range from (i) fundamental research

on single crystals (Mn3Si), where bulk thermodynamic and transport measurements were performed to elucidate the origin of electronic ordering phenomena, over (ii) the search for new material compositions of bulk-like (Fe-Co-X) films and rare-earth-lean Sm-Co/Fe multilayers with a large magnetic anisotropy, (iii) the preparation of magnet o-caloric (La-Fe-Si) composite materials with a wear close to application requirement s, and (iv) studies of the micro-structural dynamics of magnetic shape- memory alloys (Ni-Mn-Ga) to (v) resolving the real structure of commercially used materials (Nd-Fe-B) at the atomic level. Related goals are (i + ii) the identification of new material compositions with potentially application-relevant properties; (iii + iv) the detailed understanding and tuning of known material classes toward specific applications; and (v) the optimization of applied materials.

(i) Spin density wave order and fluctuations in Mn3Si In many systems, there is an intimate connection between electronic ordering phenomena and unconventional superconductivity. A prime and recent example represents the class of Fe-pnictides where the suppression of the spin density wave (SDW) leads to the emergence of superconductivity. Hence, itinerant antiferromagnetic intermetallic compounds with a SDW transition may be seen as model systems for advancing the 18 Research Area 1 FUNCTIONAL QUANTUM MATERIALS

Fig. 1: (a) Specific heat, (b) resistivity of Mn3Si.

Inset (a): construction of TN. Inset (b): resistivity of LaFeAsO [1].

understanding of such electronic ordering phenomena with Mn3Si being an example in the class of Heusler compounds (TN = 21 K) [1] and CrB2 a representative with an hexagona l structure similar to MgB2 (TN = 88 K) [2]. We have studied the specific heat, electrical resistivity (Fig. 1), thermal conductivity, Hall effect, Seebeck effect, and Nernst effect of a Mn3Si single crystal in the temperature range from 10 K up to 300 K [1]. Clear anomalies are observed at the SDW transition in all transport coefficients. These anomalies originate in both strongly temperature- dependent changes of the relaxation time and of the Fermi-surface topology in response to the SDW transition. Moreover, we find strong evidence for a large fluctuation regime which extends up to ∼ 200 K in the resistivity, as well as in the Seebeck and Nernst effects. This extended fluctuation regime may be interpreted as the signature of competing orders in Mn3Si. A comparison of our results on Mn3Si with other prototype SDW materials, viz., the iron arsenide LaFeAsO and the classical SDW prototype chromium reveals a generic manifestation of the SDW in transport coefficients.

(ii) Rare-earth-free and rare-earth-lean films with a large magnetic anisotropy As an alternative approach to obtain rare-earth free permanent magnets we explore the suitability of Fe-Co-X films which are strained in order to induce magnetocrystalline anisotropy. For a systematic search by combinatorial methods together with RU Bochum a composition spread of epitaxial Cu-Au was examined, which allows for a large variation of in-plane lattice parameters [3]. While this approach aims to induce strain by coherent epitaxial growth, which is limited to film thicknesses of a few nm [4], the use of additional Carbon induces a spontaneous strain [5]. With this also thick films can be prepared, which reach a magnetocrystalline anisotropy up to 0.4 MJ/m3.

Making use of the unprecedented magnetocrystalline anisotropy of the hexagonal

SmCo5 phase in epitaxial nanoscaled Sm-Co/Fe multilayer heterostructures allows the 3 realization of record energy densities (BH)max > 450 kJ/m in a rare-earth-lean magnet.

Figure 2 shows the dependence of (BH)max on the individual layer thicknesses and multilaye r architecture in SmCo5 /[Fe/SmCo5]n , with n = 1 (3-layer sample) and n = 2 (5-layer sample). Research Area 1 FUNCTIONAL QUANTUM MATERIALS 19

Fig. 2: Energy density (BH)max of 3-layer and 5-layer Sm-Co/Fe samples as a function of Fe-volume fraction.

(iii) Magneto-caloric composites

Magneto-caloric La(Fe,Si)13 is usually very brittle and requires the combination with anothe r material in order to form a regenerator that will survive millions of cycles in a magneto-caloric cooling device. At IFW, a novel magneto-caloric composite based on

La(Fe,Si)13 particles in an amorphous metallic matrix has been studied [6], see Fig. 3. Magneto-caloric particles and a powderized Pd-based glass were hot-compacted at the

glass transition temperature, Tg, of the metallic matrix. At this temperature, the viscous

matrix can easily fill the pores between the La(Fe,Si)13 particles, thereby creating a dense composite. Furthermore, the matrix acts as a buffer during the hot-compaction and prevent s crack formation in the magneto-caloric particles, which is otherwise known to reduce their performance. Tuning our processing route, the magneto-caloric properties of the composites are almost independent of the compaction pressure.

Another possibility to form magneto-caloric composites is to combine La(Fe,Si)13-based particles of various size fractions with a polymer matrix [7]. Such composites were pressed into thin plates of about 200 mm thickness, a geometry favorable for the subsequent testing of the composites in an active magnetic regenerator (AMR). We found that a higher filling factor which can be achieved by using a mixture of several particle size fractions has beneficial influence not only on the mag - neto-caloric properties, but also on the thermal conductivity. Tests in the AMR revealed that a maximum temperature span of approximately ΔT = 10 K under a

magnetic field change of μ0H =1.15T can be obtained without cooling load. The stability of the measured ΔT values and the mechanical integrity of the sample after cyclic application of a

Fig. 3: Hot compaction of a La(Fe,Si)13-based magnetic field have been monitored for composite at Tg of the amorphous component. 90,000 cycles and showed very good stability of the magneto-caloric performance. 20 Research Area 1 FUNCTIONAL QUANTUM MATERIALS

MagKal - a good-practice-project of technology transfer Based on the magnetocaloric effect (MCE) the efficiencies of cooling devices and heat pumps might be notably improved. Estimates of about 40% reduction in electricity consumption are tempting the industries to get early access to this new technology and to have it ready for the market launch. Keeping industrial and household applications in mind, each new technology has to compete with the established compressor cycle. Continuousl y improved during the last century the marked is almost flooded with cheap refrigerators and heat pumps providing sufficient temperature span, thermal power and reliable operation for decades. Considering this starting point most of the research activities in the fields of magnetocalorics have to be rated concerning their contribution to further applications. The literal meaning is that materials, showing a sufficient MCE have to be at the same time mechanically stable, have to resist corrosion, and have to be available worldwide in big quantities and for low costs. Concurrently the machinery around the MCE materials has to provide efficient heat transfer into the thermal process by requiring minimal quantities of magnetic materials and less electricity than a cooling compressor. From the existing state of knowledge these challenging targets cannot be met at once. A screening process, investigating the various options of building a MCE- machine, was started in 2012 with the project “MagKal”, aiming to build an operating MCE-machine. Beyond the technical issues the market potentials of the technology should be gauged as well, so finally the project setup has to integrate all the required disciplines as depicted below: material science

The interdisciplinarity of “MagKal” thermodynamicsMCE-machine market analysis was covered by the setup of the project team. For the material aspects and the engineering part the IFW was in charge. The Technical University Dresden contributed to the thermal issues. Finally an expert from the electrical eng. mechanical eng. industries, called the innovation mentor, joined the project team for guiding the activities in terms of their relevance to the market.

The major key issues in the project are as follows: ½ Finding and characterizing of alternative MCE-materials to Gd ½ Identifying sufficient transfer fluid and optimization of heat transfer process ½ Building of the demonstrator

During the project term quite a number of actions were taken to meet the milestones above. Some highlights are arranged exemplary below: Funded by the Federal Ministry of Education and Research the „MagKal“-project was evaluate d among 137 others and was identified as a good-practice-example. The entire project setup as well as the activitie s of the innovation mentor were regarded to be well determined on applying the MCE technology in niches like e.g. electro mobility. Compared to compressor refrigeration the MCE technology captivates with simple reversibility of the thermal cycle and the total absence of fluids which may harm the atmosphere. Nevertheless a real breakthrough in terms of replacing conventional compressor technologies in the mass market still needs appreciable efforts. The major key issue to be solved is still the development of sufficient MCE materials, a field on which future research activities should be focused. Research Area 1 FUNCTIONAL QUANTUM MATERIALS 21

(iv) Magnetic shape-memory alloys: transformation mechanisms and finite size effects In order to understand the transformation behavior of magnetic shape memory alloys we localized the sources of acoustic emission during a martensitic transformation in collaboration with the University of Barcelona and Academy of Science in Prague [8]. Acoustic avalanches are a general feature of solids under stress, e.g., evoked by external compression or arising from internal processes like martensitic phase transformations. From integral measurements, it is usually concluded that nucleation, phase boundary pinning, or interface incompatibilities during this first-order phase transition all may generate acoustic emission. We studied local sources of acoustic emission to enlight the microscopic mechanisms. From two-dimensional spatially resolved acoustic emission measurement and simultaneous optical observation of the surface, we identified microstructural events at the phase boundary that lead to acoustic emission. A resolution in the 100-μm range was reached for the location of acoustic emission sources on a coarse-grained Ni-Mn-Ga polycrystal. Both, the acoustic activity and the size distribution of the microstructural transformation events, exhibit power-law behavio r. The origin of the acoustic emission are elastically incompatible areas, such as differently oriented martensitic plates that meet each other, lamellae growing up to grain boundaries, and grain boundaries in proximity to transforming grains. Using this result, we proposed a model to explain the decrease of the critical exponent under a mechanical stress or magnetic field.

To probe finite size effects in ferromagnetic shape memory nanoactuators, together with the KIT double-beam structures with minimum dimensions down to 100 nm were designed, fabricated, and characterized in-situ in a scanning electron microscope with respec t to their coupled thermo-elastic and electro-thermal properties [9]. Electrical resistance and mechanical beam bending tests demonstrate a reversible thermal shape memory effect down to 100 nm. The comparison of surface and twin boundary energies allow to explain why free-standing nanoactuators behave differently compared to constrained geometries like films and nanocrystalline shape memory alloys.

(v) Interfaces in Nd-Fe-B magnets at the atomic scale The crystal structure and chemical composition of interfaces in Nd-Fe-B magnets has been studied at unprecedented spatial resolution using a combination of aberration- correcte d scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS). These techniques allowed variations in the concentrations of

mino r alloying elements near the surfaces of the Nd2(Fe,Co)14B grains to be detected on the atomic scale [10]. Figure 4 shows EELS elemental profiles overlaid on the

Fig. 4: The local distribution of elements at a phase boundary in a Nd-Fe-B magnet shown at the sub-nm scale by elemental profiles overlaid on the corresponding image. 22 Research Area 1 FUNCTIONAL QUANTUM MATERIALS

correspondin g high angle annular dark field (HAADF) image. The image shows a grain of Nd2(Fe,Co)14B on the left and the interface to an intergranular phase on the right. The last vertical line of bright points from the left is the terminating plane of atoms of the

Nd2(Fe,Co)14B grain. Enrichment of Co in the outermost unit cell of the Nd2(Fe,Co)14B and interfacial segregation of Cu were observed (Fig. 4). Co is known to have a detri - mental effect on the coercivity of the material but such local concentrations have not been previously observed. Molecular dynamics simulations of grains with and without Co enrichment at the surface showed that the magnetoelastic anisotropy was reduced in the Co enriched region. This is also likely to have a detrimental influence on coercivity. The results contribute to the fundamental understanding of coercivity in Nd-Fe-B magnets and may be used to guide experiments in enhancing coercivity in future materials.

[1] F. Steckel et al., Phys. Rev. B 90, 134411 (2014) [2] A. Bauer et al., Phys. Rev. B 90, 064414 (2014) [3] S. Kauffmann-Weiss et al., APL Materials 2 (2014) 046107 [4] L. Reichel et al., J. Appl. Phys. (2014) accepted [5] L. Reichel et al., J. Appl. Phys. 116 (2014) 213901 [6] M. Krautz et al., Scripta Materialia 95 (2015) 50 [7] B. Pulko et al., J. Magn. Magn. Mat. 375 (2014) 65 [8] R. Niemann et al., Phys. Rev. B. 89 (2014) 214118 [9] M. Kohl et al., Appl. Phys. Lett. 104 (2014) 043111 [10] T. G. Woodcock et al., Acta Mater. 77 (2014) 111

Cooperation: 1TU München, 2MLZ Garching, 3 Inst. Physics Prague, 4Ruhr-University Bochum, 5Helmholtz-Zentrum Dresden-Rossendorf, 6Demokritos National Center of Scientific Research Athens, 7Uppsala University, 8 TU Darmstadt, 9University of Ljubljana, 10Parker Hannifin Manufacturing Srl, 11Universitat de Barcelona, 12Karlsruhe Institute of Technology, 13SuperSTEM, 14University of Exeter, 15 Toyota Motor Corporation, 16 TU Dresden, Audi AG, TU Eindhoven, Polish Academy of Sciences, Universität Kaiserslautern, Universität zu Köln, MPI CPFS, Dresden, Ohio State University

Funding: Audi AG, DFG Research Area 1 FUNCTIONAL QUANTUM MATERIALS 23

Research Topic 1.4 Engineering magnetic microtextures People: M. M. Abd-Elmeguid8, A. Barla7, A. N. Bogdanov, S. Chadov6, M. Deutsch4, C. Felser6 ,P. Fischer2, C. Hengst, J. Körner, K. Koepernik, F. Kronast1, E. Lopatina, D. Makarov, O. Meshcheriakova6, I. Mirebeau4, Th. Mühl, A. K. Nayak6, V. Neu, C. F. Reiche, U. K. Rößler, Z. Sasvari3, R. Schäfer, M. Schmidt6, I. Soldatov, R. Streubel, K. Tschulik, M. Uhlemann, S. Vock, H. Wilhelm5, M. Wolf, U. Wolff Responsible Directors: B. Büchner, O. G. Schmidt, L. Schultz, J. van den Brink

Summary: The unique properties of non-trivial topological states, e.g. magnetic skyrmions [1] may path the way towards novel spintronic devices [2]. However, these spin textures have only been observed in special classes of materials possessing non- centrosymmetric crystal structure [1, 3-6] and at low temperatures, which limits their application potential. Within research topic 1.4 we focus on realizing novel and con- figurable inhomogeneous magnetization states such as skyrmions and chiral domain walls at room temperature and on their thorough static and dynamic study. Effort is dedicated to the search of appropriate magnetic phases by first-principle calculations, to the preparation of coupled multilayer systems with chiral magnetization states and their investigation by magnetic x-ray and Kerr microscopy, and to the further development of optical and scanning probe microscopy techniques for an improved characterization of magnetic microtextures on variable length and time scales. The following examples summarize the progress in the theoretical description of chiral helimagnets, in the realization of chiral magnetization states imprinted into Co/Pt/Py multilayers and in new developments in magnetic force microscopy (MFM), namely depth resolved quantitative MFM and a new sensing concept based on coupled oscillators .

Search for skyrmionic states and phases in chiral helimagnets Search for skyrmionic states and phases in chiral helimagnets remains a challenge, owing to the specific requirements on symmetry and secondary magnetic properties like magnetic anisotropies and magneto-elastic couplings. With a combination of theoretical and computational approaches we predict these properties in magnetic materials to guide and support this search. In cooperation with external experimental groups we have performed studies on the transition metal germanides FeGe and MnGe with 24 Research Area 1 FUNCTIONAL QUANTUM MATERIALS

B20-structure, which are the archetypical chiral cubic helimagnets. In both materials, the application of high pressure allows to reach unconventional magnetic states near the collapse of magnetic order, while evidence for skyrmionic states exists for both compounds also at ambient pressure. A combination of neutron scattering experiments, magnetic measurements, and ab initio calculations uncovered an evidence for a spin-state transition in MnGe from a high-spin to a low-spin transition under hydrostatic pressure [7], an effect that has been predicted by us earlier. In future, it remains to be seen whether the helimagnetism of MnGe with an uncommonly short and temperature- variabl e period at ambient pressure can be explained by the proximity of the magnetic system to this spin-state transition. In the classical chiral helimagnet FeGe, a Mössbauer experiment under pressure shows the existence of an inhomogeneous chiral magnetic precursor state [8]. In this quasi-static state reached without proper phase transition from the paramagnetic side, the longitudinal magnitude of the spin-density is inhomogeneous and quasi-static on the time-scale of the Mössbauer experiment. The experiment provides important evidence for the unconventional type of magnetic ordering transition via intermediate mesophases in chiral helimagnets. The interpretation of the experimental results required a detailed calculation for the evolution under pressure of the hyperfine parameters in FeGe by density-functional theory calculations using the in-house FPLO-code. We have started a cooperation with groups at the Max Planck Institute, CPFS Dresden to analyse tetragonal Heusler-type compounds of type Mn2YZ. In these systems, ferrimagnetic or canted spin-structures with large non-collinear order and co-existence of ferromagnetic and antiferromagnetic order-parameters in bicritical phase-diagrams are combined with the existence of inhomogeneous Dzyaloshinskii-Moriya-couplings. These complex and versatile systems promise novel types of skyrmionic states [8]. In particula r, the specific low symmetry of these compounds should allow to realize the field-induced hexagonal skyrmion lattices that should be named Bogdanov-Hubert- phase following the first prediction of this condensed skyrmion phase in the ground-state of phase-diagram of chiral helimagnets in absence of competing conical helix-phases.

Magnetic chiral spin textures via imprinting We offer an alternate route to design synthetic magnetic heterostructures that re- semble swirls, vortices or skyrmions with distinct topological charge densities at room temperature. By vertically stacking two magnetic nanopatterns with in- and out-of-plane magnetization and tailoring the interlayer exchange coupling, non-collinear spin textures with tunable topological charge can be imprinted (Fig. 1a). The concept is demonstrated on nanostructures consisting of soft-magnetic 40 nm thick Permalloy (Py, Ni80Fe20) and 5 nm thick Co/Pd multilayers. First, we conduct systemati c micromagnetic simulations of the magnetic spin texture in a disk-like heterostructure with a diameter of 400 nm where the interlayer exchange coupling strength between Py and Co/Pd sub-systems is varied from 0.1 to 2 mJ/m2. In strongly coupled heterostructure, the magnetic state of the Co/Pd is determined by the spin configuration in the Py disk resulting in the in-plane circulation of the magnetization thus resembling magnetic vortex state (Figs. 1b,c). At an intermediate coupling strength, remanent donut states with a central vortex within the Co/Pd layers occur. Driving full or minor hysteresis loops allows to stabilize topologically distinct donut states with topological charges of about 1 and 0. The resulting magnetic configuration of the donut state, achieved at remanence after saturating the sample, is similar to those found in a disk with Dzyaloshinskii-Moriya interaction [10] hence suggesting that skyrmion-like structures can be experimentally realized in exchange coupled heterostructures. Owing to the larger switching field of the vortex core compared to the surrounding Co/Pd spins, the reversible switching between these states can be achieved. In this way, the topological charge can be switched in a digital manner at room temperature and at zero field Research Area 1 FUNCTIONAL QUANTUM MATERIALS 25

Fig. 1: a) Conceptual figure: Vertically stacking the out-of-plane magnetized and magnetic vortex state allows to imprint the non-collinear spin textures into the originally out-of-plane magnetized film. (b) Ensemble of remanent states obtained by micromagnetic simulations of nanopatterned disks. (c) Experimental proof via MXTM of imprinting magnetic vortices into Co/Pd multilayers with originally out-of-plane anisotropy. (d) Simulations show that an intermediate interlayer coupling strength allows for switching the topological charge of donut states at remanence and at room temperature by applying small magnetic fields. (e) Line profile of the out-of-plane magnetization component for donut state I and II and magnetic spiral.

(Fig.1d). As our concept does not rely on vortex polarity switching in contrast to [11], much lower static magnetic fields are needed to manipulate the topological state of the material. We have experimentally studied the magnetization reversal process and magnetic domain patterns in nanostructured [Co/Pd]/Pd/Py stacks sputter deposited onto assemblies of non-magnetic silica spheres with a diameter of 500 nm. The Pd spacer thickness is varie d from 1 to 30 nm. Evidence for the stabilization of non-collinear spin textures in the Co/Pd layers is provided by direct imaging of the magnetization patterns utilizing X-ray magnetic circular dichroism (XMCD) with high resolution magnetic soft X-ray transmission microcopy (MTXM) and X-ray photoemission electron microscopy (XPEEM). For a 1 nm spacer thickness a vortex structure is observed (Fig. 1c), in agreement with theoretical predictions. At 3 nm spacer thickness, an out-of-plane magnetization component appears in the Co/Pd sub-system. However, the circulation of the in-plane magnetization component still remains. For this sample, we clearly identify formation of different donut states as well as multi-domain states (Fig. 1e). The experimentally resolvab le in-plane XMCD contrast in Co/Pd stack vanishes for the sample with 5 nm spacer thickness. The core of the imprinted vortex in the Co/Pd multilayer is enlarged (60-110 nm) with respect to the Py vortex core due to the additional intrinsic out-of- plane anisotropy of Co/Pd. 26 Research Area 1 FUNCTIONAL QUANTUM MATERIALS

Fig. 2: Calculated MFM signal (top right) in comparison with experimental MFM signal (bottom right) of a CoFe nanowire array. The effective surface charge model (top left) is based on the visible magnetization orientation within each nanowire and the precise charge profile derived from micromagnetic simulations (bottom left).

Magnetic vortex observation in FeCo nanowires by quantitative magnetic force microscopy (qMFM) An approach is presented that allows quantifying the three dimensional magnetization pattern of a magnetic nanoobject from measured two dimensional magnetic force microscop y (MFM) data. It is based on (i) a MFM deconvolution approach, which quantitatively characterizes the imaging properties of a MFM tip at a given height above the sample surface (tip transfer function) [12, 13], (ii) on a micromagnetic calculation of the total magnetic charges of the magnetic nanoobject and a projection of the lower ly- ing charges onto the sample surface, (iii) a convolution of the such obtained effective surface charges with the tip transfer function to obtain a theoretical MFM image, and (iv) a comparison with the experimentally measured MFM signal. By making use of the depth sensitivity of MFM and by applying a quantitative contrast analysis, we are able to reconstruct the inhomogeneous magnetization state at the end of individual cylindrical Fe52Co48 nanowires arranged in a triangular array. Figure 2 shows an experimental top-surface MFM image of a CoFe nanowire array in its demagnetized state with arbitrary magnetization state (either up or down) along the length of each nanowire, visible from the dark or bright contrast. A surface charge model is convolved with the tip transfer function (TTF) of the previously characterized MFM tip, resulting in a theoretical MFM pattern. Assuming a homogeneously magnetized nanowire with appropriat e saturation polarization overestimates the measured signal by a factor of 2 (not shown here). Including the magnetization vortex at the very end of the nanowires as derived from micromagnetic calculations not only leads to a very good qualitative but also to a perfect quantitative agreement. This is the first experimental proof of the vortex state at the end of an embedded magnetic nanowire [14]. Research Area 1 FUNCTIONAL QUANTUM MATERIALS 27

Fig. 3: Sketch of a coupled mechanical oscillator, consisting of a micron-sized oscillator (1) and a nanowire oscillator (2), with interaction to be measured.

Nanomagnetic probes and magnetometers based on coupled oscillators We developed a concept of coupled mechanical oscillators consisting of a nanowire oscillator (2) attached to a micron-sized oscillator (1) with tuned eigenfrequencies of the individual oscillators (Fig. 3). Applied to cantilever magnetometry and magnetic force microscopy, such coupled systems constitute very sensitive probes. This concept has been confirmed by simulations (Fig. 3) and first experiments.

[1] U. K. Rößler et al., Nature 442 (2006) 797 [2] A. Fert et al., Nat. Nano 8 (2013) 152 [3] X. Z. Yu et al., Nature 465 (2010) 901 [4] F. Jonietz et al., Science 330 (2010) 1648 [5] S. Heinze et al., Nat. Phys. 7 (2011) 713 [6] N. Kanazawa et al., Phys. Rev. Lett. 106 (2011) 156603 [7] M. Deutsch et al., Phys. Rev. B 89 (2014) 180407(R) [8] A. Barla et al., Phys. Rev. Lett. 114 (2015) 016803 [9] O. Meshcheriakova et al., Phys. Rev. Lett. 113 (2014) 087203 [10] H. Du et al., Phys. Rev. B 87 (2013) 014401 [11] J. Li et al., Nat. Commun. 5 (2014) 4704 [12] H. Hug et al., J. Appl. Phys. 83 (1998) 5609 [13] S. Vock et al., IEEE Trans. Magn. 47 (2011) 2352 [14] S. Vock et al., Appl. Phys. Lett. 105 (2014) 172409

Funding: DFG, ERC

Cooperation: 1BESSY II, Germany; 2Lawrence Berkeley National Laboratory, USA; 3 TU Dresden, Germany; 4CEA Saclay, Laboratoire Leon Brillouin, France; 5Diamond Light Source, UK; 6Max Planck Institute, CPFS Dresden, Germany; 7University Cologne, Germany; 8ALBA Synchrotrone, Barcelona, Spain 28 Research Area 1 FUNCTIONAL QUANTUM MATERIALS

Research Topic 1.5 Topological states of matter Authors: S. Kourtis, T. Neupert1, C. Chamon2, C. Mudry3, M. Daghofer People involved: B. Dassonneville, J. Dufouleur, V. Fomin, H. Funke, R. Giraud, S. Hampel, V. Kataev, F. Kirtschig, K. Koepernik, A. Lau, P. Leksin, S. Li, L. Ma, U. Nitzsche, C. Nowka, C. Ortix, S. Pandey, G. Prando, M. Richter, L. Veyrat, T. Weißbach, K. Wruck, Y. Yin, S. Zimmermann, J. Zocher Responsible Directors: B. Büchner, O. G. Schmidt, J. van den Brink

Strong correlations in Chern bands The recently discovered prospect of realizing fractional quantum-Hall (FQH) states with the inclusion of short-range interactions in lattice models has garnered considerable interest. Apart from a paradigmatic extension of the FQH effect to lattices, these states, called fractional Chern insulators (FCI), arise without an externally applied magnetic field. Hence, they are an important conceptual step towards potential technological applications.

There are already several proposals for the realization of FCI states, some of which involve optical lattices, while others are based on known material structures, such as strained or irradiated graphene, oxide heterostructures, or layered multi-orbital systems proposed by our group [1, 2]. The latter category is particularly promising, since the energ y scales at which the desired physics emerges is of the order of room temperature.

Since their inception, FCI states have been studied with various numerical and analytical methods. Of particular interest are works that emphasize the differences between FCI states and traditional FQH physics. The most obvious difference is that Chern bands, unlike Landau levels, have a non-vanishing dispersion. In an earlier work, we have proven by example that this dispersion may actually favor FCI states [2]. Unlike FQH system s, FCI models can be naturally extended to include both spin species, and it has been shown that the resulting time reversal-symmetric models can be hosts of frac - tional topological insulators. Since the Chern number of a band can, in contrast to a Landau level, take values larger than one, FCI states can occur in partially filled bands with higher Chern numbers. Finally, topologically ordered states that go markedly beyond the Landau-level picture, in which the topological character is combined with Landau-type order, have been found by two of us recently [3]. Research Area 1 FUNCTIONAL QUANTUM MATERIALS 29

Fig. 1: Phase diagrams of (a) the triangular If one wishes to search for FCI states in the laboratory, understanding of how these states and (b) the checkerboard lattice models on can arise in realistic multiband systems is crucial. In Ref. [4], we pose two fundamental a 48-site cluster at ν = 1/3, V = ∞ in the 1 questions for the realization of FCI states, namely (i) whether the mixing of bands by plane spanned by the chemical potential interaction s leaves space for FCI states to arise, and (ii) whether FCI states can be found μs and the third nearest-neighbor hopping t3.The color coding is the lowest value of the far beyond the energy scale of the band gap. To this end, we have studied two proto- gap between FCI ground states and excited typical two-sublattice FCI models using exact diagonalization, taking both Chern bands states upon flux insertion. The dashed white into account [4]. We show that FCI states survive band mixing caused by arbitrarily large line in (b) denotes the phase boundary for interactions. To demonstrate this, we introduce the extreme limit of nearest-neighbor the non-interacting model. interaction going to infinity. In this regime, particles dressed by the interaction form extended objects, which can be interpreted as non-interacting hardcore particles occupying more than one lattice sites. We find that strong interactions of magnitude far larger than the band gap may actually favor FCI states, regardless of whether the bands are mixed, see Fig. 1.

Within the FCI regime (the colored part of the phase diagrams in Fig. 1), the ground-state eigenvalues exhibit the empirical characteristic features of FCI states: 3-fold degener- acy and spectral flow. In order to establish beyond doubt that the phase is indeed an FCI, we calculate the Hall conductivity in this regime and find it to be very precisely quantize d to the value -1/3 [4].

In [3], we go beyond the limit of „weak“ interactions, into a regime where different Chern bands mix. We find states that show the features of both a CDW and of an FCI and, thus, arrive at an exotic state of matter that is characterized by both Landau-type and topologica l order and is understood in terms of both band topology and lattice geometry. This novel class of states can be intuitively understood as comprising of particles that play two roles simultaneously. Most of them form the CDW occupying 1/3 of the triangular lattice sites, see Fig. 2(b). Additional particles can then move on the remaining sites, up to a total density of n = 2/3 (two fermions per three lattice sites). One can view the remaining sites as an effective honeycomb-lattice model, which has here a 4-site unit cell, see Fig. 2 (b), and is described by topologically nontrivial hoppings.

Fig. 2: Charge density wave (CDW) and fractional Chern insulator (FCI) on the triangular lattice at a density n = 1/3. (a) Phase diagram of the model used in Ref. [3] for a 3 x 3 unit-cell

(6 x 3 lattice-site) system with 6 fermions and only nearest-neighbor repulsions V1. (b) The 4 x 4 - 1 = 15 unit-cell (30 lattice-site) cluster used in Ref. [3]: the unit cell (black/red circles), the charge-order pattern (filled circles) arising in the CDW and the hoppings. Solid, dashed and arrowed black lines represent complex hoppings t with phases of 0, π and ±π/2, respectively. Grey lines denote hoppings deactivated by the CDW. Third nearest-neighbor hoppings t’ are not shown. 30 Research Area 1 FUNCTIONAL QUANTUM MATERIALS

The eigenvalue spectra of our interacting spinless-fermion model on the triangular lattic e at filling fractions ν = 12/15 and 13/15 hint at ground states that are neither FCI nor CDW, but have features of both. The Landau order, commensurate charge modulation in the ground states, reveals itself in the interaction strength-dependent peaks in the static charge-structure factor. The topological order is established via the Hall conductivity, which is precisely quantized, but with a value σH ≠ ν. Instead, we find a quanti- zation consistent with viewing the ground states as composites of a CDW state and a FCI state formed by additional particles in the part of the lattice that remains unoccupied by the CDW [3].

[1] J.W.F. Venderbos et al., Phys. Rev. Lett. 108 (2012) 126405. [2] S. Kourtis et al., Phys. Rev. B 86 (2012) 235118. [3] S. Kourtis and M. Daghofer, Phys. Rev. Lett. 113 (2014) 216404. [4] S. Kourtis et al., Phys. Rev. Lett. 112 (2014) 126806.

Collaborations: 1Princeton University, Princeton, New Jersey 08544, USA; 2Boston University, Boston, Massachusetts 02215, USA; 3Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland

Funding: DFG Research Area 2 FUNCTION THROUGH SIZE 31

Research Topic 2.1 Non-equilibrium phases and materials Authors: S. Pauly, J. Freudenberger, S. Scudino, U. Rößler People involved: H. Attar, M. Calin, B. Escher, P. Gargarella, T. Gemming, I. Kaban, A. Kauffmann, M. Samadi Khoshkhoo, K. Kosiba, U. Kühn, P. Ma, K. G. Prashanth, P. Ramasamy, H. Shakur Shahabi, M. Stoica, H. Turnow, Z. Wang, H. Wendrock Responsible Directors: J. Eckert, L. Schultz, J. van den Brink

Summary: The most prominent characteristic of non-equilibrium materials is the energeticall y unfavourable state they have adopted during their synthesis. The entire microstructure or parts of these materials are in structural, compositional or morpho- logical metastability, which defines their unusual and interesting mechanical, chemical and physical properties [1]. Some of the eldest and probably best-known examples comprise silicate glasses or martensite formation in steels. A wide variety of other, novel non-equilibrium materials are the objects of the research conducted in research area 2.1. The present report shall give a glimpse of the diversity of materials and methods used to obtain and to characterise them. Therefore, as a cross section, this treatise covers bulk metallic glasses (BMGs), BMG matrix composites, cryomilled, nanostructured Cu as well as heavily deformed metals and alloys.

Strain determination in a metallic glass by X-rays Understanding the deformation mechanisms in metallic glasses is a very challenging task. The structural entities, which govern deformation in metallic glasses (shear transformatio n zones, STZs), are of very small size and cannot be unveiled directly [2,3]. However, diffraction using high-energy X-rays is capable of revealing details of the structure, which allow the determination of the local strain state in the glass [4,5]. That way, the occurrence of shear bands, which result from the coalescence of STZs, can be better understood and their formation can be correlated with the local strains–or the structure.

Fig. 1: Schematic setup of the diffraction experiment Here, the surface of a Zr52.5Ti5Cu18Ni14.5Al10 bulk metallic glass was structured by imprint- at the ESRF. The beam is parallel to the imprinted ing a line pattern with a steel mould at room temperature [6]. This forces the glass to grooves at the sample surface. For each point deform plastically and leaves periodic grooves at the surface (Fig. 1). The sample was indicated a 2D-diffraction pattern was recorded and then integrated. The shift in the peak positions then scanned with a high-energy X-ray beam (Fig. 1) and the local strains were calcu- reflects the local strains in the glass. lated from the shift of the first diffraction maximum [4,7]. 32 Research Area 2 FUNCTION THROUGH SIZE

Fig. 2: Components of the strain tensors of the imprinted glass.

(a) εxx (tangential): parallel to the imprinted surface.

(b) εyy (axial): normal to the imprinted surface and

(c) εxy: in-plane shear. Oscillations between compressive and tensile strains can be revealed and especially the in-plane shear is rather pronounced.

The three components of the strain tensor (εxx, εyy, εxy) were determined for each point to create spatially resolved strain maps. Figures 2(a)-2(c) show the strain components, which are negative for compressive and positive for tensile strains. Character- istic patterns of alternating tensile and compressive strains are obtained. Especially the in-plane strains (εxy) are rather pronounced. A comparison between the medium-range order (MRO, first diffraction maximum) and the short-range order (SRO, higher order maxima) suggests a significant structural anisotropy. The shear strains in Fig. 2 are much larger than the elastic shear components obtained from X-ray experiments during uniaxial loading, which are close to zero [4,8]. The shear band pattern after deformation of the imprinted BMGs clearly proves that the generation of shear bands is governed and affected by these residual strains.

Steel spring-metallic glass composite Monolithic bulk metallic glasses tend to fail in a brittle fashion [9]. The reason for this is the formation of shear bands already mentioned above. Once they form, the glass becomes softer and the shear bands preferentially transform into cracks [2,9]. One way to overcome this limited damage tolerance is to incorporate a second, crystalline phase [10,11]. The crystalline phase interacts with the formation of these shear bands and aggravate s their propagation and thus retards fracture [10]. A special case of such a composite is shown in Fig. 3: a steel spring of a ball pen was infiltrated by a glass-forming Zr52.5Ti5Cu18Ni14.5Al10 melt (inset in Fig. 3) [12]. The longitudinal cut of this sample shows the glassy matrix and the relatively darker steel spring (Fig. 3). Even though the wetting of the spring is not always sufficient (voids in Fig. 3) the plasticity can be significantly enhanced as the compression tests prove (Fig. 4 (a)). The strength of the composite is somewhat lower but this sacrifice is counterbalanced by a substantial increase in the plastic deformability. Moreover, the dynamics of the shear banding process are altered due to the presence of the steel spring. Relatively large stress Fig. 3: Micrograph (scanning electron microscope) drops followed by elastic loading are observed in the case of the as-cast metallic glass of longitudinal cut through the spring-glass com- (Fig. 4 (b)). In contrast, much more serrations appear in the spring-glass composite and posite. The dark circles represent the spring and the energy release for each serration is also much smaller. the inset illustrates how the spring was infiltrated. Research Area 2 FUNCTION THROUGH SIZE 33

Fig. 4: (a) Stress-strain curves of the composite in compression. The composite has a much larger plastic deformability and also the dynamics of the shear banding process changes. (b) for the as-cast material less serration events occur and the elastic energy density of each event is larger than in the case of the composite (c).

Nanostructured Cu through cryomilling The metallic glasses mentioned above were all obtained via quenching of a melt. An- other route to obtain glasses for instance is ball milling [1]. Depending on the powder composition and the milling parameters not only metallic glasses can be synthesised but also nanocrystalline metallic materials [13]. In this context, it is crucial to understand the mechanisms as of how the nano-scale microstructure evolves. This can be done by detailed X-ray diffraction line analysis coupled with high-resolution transmission electro n microscopy (TEM) [14]. The grain size for cryomilled Cu obtained by TEM ranges between 10 and 200 nm (Fig. 5(a)). This is different compared to the size distribution obtained by XRD because for deformed Cu XRD provides the size distribution of dislocation cells, while TEM gives the grain size distribution. There is no sign of discontinuous dynamic recrystallisation (DDRX). Microstructural refinement occurs via dislocation activity including dislocation generation and accumulation, annihilation and recombination of dislocations to form dislocation cells, and gradual conversion of the dislocation cells to individual grains. Cu-Zn15, however, has a reduced stacking fault energy and contains very small grains with size in the range of 5 -10 nm within a heavily strained matrix made of larger grains (50 -150 nm) (Fig. 5(b)). These grains are due to the occurrence of DDRX. Dynamic recovery is inhibited and dislocation density reaches a critical value at which dynamic recrystallisation may initiate. Both structural decomposition and dynamic recrystallisation are responsible for nanostructure formation during cryomilling of Cu-Zn alloys.

Phase transformation kinetics The formation of phases from non-equilibrium conditions as e.g. heavily deformed metallic materials and composites is a measure of the phase stability of the non-equilibrium state in terms of the variables of state and time. At the same time the irreversible transformation from one state to another is comprised by a change of the microstructure. Hence, it is of great importance to detect and understand microstructural changes as well as to link them to the underlying mechanisms. Such transformations can read - ily be detected by in-situ R(T) measurements, as e.g. the formation of intermetallic Fig. 5: Frequency of grain sizes in cryomilled phases such as TiAl from pure elements of recrystallisation processes as described be- (a) Cu and (b) Cu-Zn15. The histogram represents low. As mentioned before, the microstructure of single-phase copper alloys can be altered the grain sizes obtained by high-resolution TEM and by cold deformation. Depending on the processing parameters like temperature or the the curve is obtained from X-ray diffraction line pro- stacking fault energy, the dominant deformation mechanism is different and the refine- file analysis. Due to the lower stacking fault energy, discontinuous dynamic recrystallization only occurs ment of the microstructure bears other rates with respect to the deformation strain. The in the Cu-Zn15 alloy. formation of deformation twins is activated at low homologous temperature or at low 34 Research Area 2 FUNCTION THROUGH SIZE

Fig. 6: Microstructure of Cu, CuAl1 and CuAl3 after deformation at cryogenic conditions and the derivative of the resistivity with respect to the temperature. stacking fault energy leading to smaller grain sizes achieved at a certain deformation strain. Figure 6 shows the microstructures of Cu-Al alloys after deformation at cryogenic condition s and the results of in-situ resistivity measurements. The resistivity changes associated with microstructural changes during recovery and recrystallisation during heating are highlighted by the derivative of the resistivity with respect to the temperature. Deviations of dρ/dT from this ρ0α value indicate changes of the densities of defects acting as scattering centres for electrons. Lowering the temperature during deformation causes a significant reduction of the characteristic temperature when compared to the deformation at room temperature.

[1] R.W. Cahn, A.L. Greer, in: R.W. Cahn, P. Haasen (Eds.), Physical Metallurgy, Elsevier, Amsterdam, 1996, pp. 1724 - 1830. [2] C.A. Schuh et al., Acta Mater. 55 (2007) 4067. [3] M.W. Chen, Annu. Rev. Mater. Res. 38 (2008) 445. [4] H.F. Poulsen et al., Nature Mater. 4 (2005) 33. [5] M. Stoica et al., J. Appl. Phys. 104 (2008) 013522. [6] S. Scudino et al., Scripta Mater. 65 (2011) 815. [7] T.C. Hufnagel et al., Phys. Rev. B 73 (2006) 064204. [8] J. Das et al., Rev. B 76 (2007) 092203. [9] H.S. Chen, Rep. Progr. Physics 43 (1980) 353. [10] J. Eckert et al., 22 (2007) 285. [11] C.C. Hays et al., Phys. Rev. Lett. 84 (2000) 2901. [12] H. Shakur Shahabi et al., Mater. Design 59 (2014) 241. [13] C. Suryanarayana, Progr. Mater. Sci. 46 (2001) 1. [14] M. Samadi Khoshkhoo et al., Mater. Lett. 108 (2014) 343.

Funding: DFG, US NSF, EU (BioTiNet-ITN), EU (VitriMetTech-ITN), ECEMP, Natural Science Foundation of China Foundation, Australian Research Council’s Projects funding scheme, Alexander von Humboldt Foundation (AvH), Pakistan Institute for Engineering and Applied Sciences (PIEAS), European Synchrotron Radiation Facility (ESRF), Deutscher Akademischer Austauschdienst (DAAD), China Scholarship Council, Ministry of Knowledge Economy, Republic of Korea

Cooperation: University of Vienna, Austria; University of São Carlos, Brazil; University of Cambridge, United Kingdom; University of Turino, Italy; Harbin Institute of Technology, People’s Republic of China; Edith Cowan University, Perth, Australia; Indian Institute of Technology (BHU), Varanasi, India; Yonsei University, Seoul, Korea; Tohoku University, Sendai, Japan Research Area 2 FUNCTION THROUGH SIZE 35

Research topic 2.2 Intelligent hybrid structures People: D. Ehinger, B. Escher, J. Freudenberger, D. Geißler, T. Gustmann, J. K. Hufenbach, H. Y. Jung, K. Kosiba, U. Kühn, S. Pauly, P. Ramasamy, B. Sarac, D. Sopu, A. Strehle, M. Stoica, H. Y. Jung Responsible Directors: J. Eckert, L. Schultz

Summary: The key concept of this research topic is to define new routes for creation of tailored metallic materials based on scale-bridging intelligent hybrid structures enablin g property as well as function optimization. The novelty - as compared to conventiona l ideas - is that they apply to monolithic amorphous or bulk (nano-)microcrystalline materials. The basis is founded on innovative strategies for the design, synthesis and characterization of intrinsic length-scale modulation and phase transformation under highly non-equilibrium conditions. This includes the incorporation of dispersed phases which are close to or beyond their thermodynamic and mechanical stabilit y limit, thus forming hierarchically structured and ductile/tough hybrid alloys. Alternatively, the material itself is designed in a manner such that it is at the verge of its thermodynamic/mechanical stability.

Deformable soft-magnetic bulk metallic glasses (BMGs) Ferromagnetic Fe- and (Fe,Co)-based amorphous alloys are regarded as attractive industrial alloys due to relative low price and simple routes for fabrication. Within several new

BMGs developed in the last decade, the [(Fe0.5Co0.5)0.75Si0.05B0.20]96Nb4 glassy alloy plays an important role because it combines a high glass-forming ability (GFA) with good soft-magnetic properties and very high compressive strength. However, a major draw- back of almost all Fe- and (Fe,Co)-based BMGs, which hinders their application, is the absence of sufficient plastic deformation. Generally, the routes used to enhance the deformability of glassy alloys point towards creation of a composite structure or designed heterogeneities, for example, through mechanical pre-loading or severe plastic deformation. These methods must be applied eventually with caution to Fe- and (Fe,Co)- based alloys, because the soft magnetic properties can deteriorate in the presence of non-magnetic crystalline phase(s) or due to the stress induced by mechanical treatment. A solution for magnetic BMGs can be fine-tuning the composition by adding element(s) with large Poisson ratio such as, for example, Ni or minor additions of Cu. By adding 0.5 at.% Cu to the aforementioned composition we created - for the first time - a FINEMET ®-type BMG with enhanced deformability [1]. Monolithic samples with 1 mm 36 Research Area 2 FUNCTION THROUGH SIZE

Fig. 1: Time-resolved X-ray diffraction in transmission configuration measured for

{[(Fe0.5Co0.5)0.75Si0.05B0.20]96Nb4}99.5Cu0.5 BMG. The complete measurements is truncated here between 794 K and 910 K, i.e. it starts in the supercooled liquid region of the initial fully amorphous and homogeneous BMG sample and finishes within the supercooled liquid region of the remaining amorphous matrix.

diameter revealed a fracture strain of 3.80 % and a maximum stress of 4143 MPa upon compression, together with a slight work hardening-like behavior. The soft magnetic properties are preserved upon Cu-addition and the samples show a saturation magnetization of 1.1 T combined with less than 2 A/m coercivity. The Cu-added glasses show a very good thermal stability but, in comparison with the base alloy, the entire crystallization behavior is drastically changed [2]. Upon heating, the new glassy samples show two glass transition-like events, separated by an interval of more than 100 K, in between which a BCC-(Fe,Co) solid solution is formed. This unique behavior was investigated by time-resolved X-ray diffraction in transmission configuration, using a high- intensity high-energy monochromatic synchrotron beam at the ID11 beamline at ESRF Grenoble, France. The patterns presented in Fig.1 start at 794 K, i.e. in the supercooled liquid region of the initial fully amorphous and homogeneous BMG sample and finish at 910 K, within the supercooled liquid region of the remaining amorphous matrix. The crystalline peaks superimposed to the amorphous background are characteristic for a BCC-(Fe,Co) solid solution. By appropriate control of the size and distribution of the nanograins this behavior can be further exploited for enhancing the soft magnetic properties as well as the plastic deformability even more.

BMG-Matrix Composites with crystalline TRIP/TWIP particle reinforcement It has been shown that crystalline inclusions or precipitates can enhance tensile plasticity of the BMGs. One general approach is to arrest single localized shear bands and/or to disperse the material reaction into multiple shear banding in order to retard failure. With the background of Twinning Induced Plasticity (TWIP) and Transformation Induced Plasticity (TRIP) [3-5] it is envisaged to create new BMG-Matrix Composites that have an active component as second phase. This approach has already been proven to be successful by using the formation of B2 CuZr-type particles within an amorphous CuZr-based matri x [6] that show work hardening and interact with shear bands by deformation twinning and martensitic phase transformation. We extended this approach by producing BMG-Matrix Composites through Selective Laser Melting (SLM) [7]. Here, Fe-based amorphous powders that have been successfully processed by SLM [7] into bulk amorphous samples were mixed with powders from Shape Memory Alloys (SMA) and co- Fig. 2: Hollow cylinders with 4 mm diameter and processed via SLM into BMG-Matrix Composites. Within the active temperature range 8 mm height processed via SLM from a 9:1 mixture of the SMA, similar beneficial effects on the mechanical properties of the BMG matrix of a Fe74Mo4P10C7.5B2.5Si2 (at.%) gas atomized are expected as stated above. First tests show that bulk structures can be additively amorphous powder and a Cu-11.8Al-3.2Ni-3.0Mn (wt.%) SMA powder: (a) using the set of parameters manufacture d from mixtures of Fe Mo P C B Si (at.%) based amorphous powders 74 4 10 7. 5 2.5 2 adapted to the SLM of the Fe-based powder as in [7], and Cu-11.8Al-3.2Ni-3.0Mn (wt.%) SMA powders by the SLM technique. Fig. 2 shows (b) improved set of parameters adapted to the SLM hollo w cylinders with 4 mm diameter and 8 mm height processed via SLM from a 9:1 of the Cu-based SMA. Research Area 2 FUNCTION THROUGH SIZE 37

mixture of these FeMoPCBSi gas atomized amorphous and CuAlNiMn SMA powders manufacture d using (a) a SLM set of parameters adapted to the processing of Fe-based powder [7] and (b) an improved set of parameters, adapted to the SLM of the Cu-based SMA. The properties of these composites are currently investigated.

Development and study of Co-based metallic glasses and composites Another subject of the INTELHYB research topic focuses on the development and study of novel high-strength and soft-magnetic Co-based metallic glasses and composites. Since direct casting of these materials into rods is very challenging and mostly un - successful, other techniques like melt-spinning and gas-atomization were applied as

the pre-processing steps. The investigated melt-spun Co66Hf6.5B27.5, Co56Fe10Hf6.5B27.5

and Co40Fe22Hf6.5B31.5 (at.%) amorphous ribbons exhibit average thicknesses in the range of 18 to 67 μm, and band widths between 1.5 and 4 mm depending on the cham- ber pressure, the wheel speed and the casting temperature. So far, the best surface quality and highest bend fracture angle (as a first indicator for ductility) was achieved for

Co56Fe10Hf6.5B27.5 ribbons. Fig. 3(a) shows an as-spun 1.5 mm wide Co56Fe10Hf6.5B27.5 ribbon which exhibited the best deformability. The ribbon is very uniform and ductile. Yet, there are still demands for optimization with respect to the sample dimensions for potential future applications.

Fig. 3: (a) As-spun 1.5 mm wide very uniform and ductile Co56Fe10Hf6.5B27.5 ribbon showing the best deformability. (b) Snapshot of the atomization process of the Co40Fe22Ta 8B30 alloy. The central stream of the molten alloy is further spread at the intersection of the water jet (the laminar jet in the picture coming out from the left nozzle) and the symmetrical Ar gas jet (invisible here, coming out from the right nozzle). The powder is collected in a water-filled tank placed below the atomization point.

Co40Fe22Ta8B30 and Fe-based reference materials were gas-atomized by ejecting the molten metal via a dual in-house upgraded water/Ar jet system, and finally quenching in water. The powders have a narrow particle size distribution between 100-150 μm for a nozzle slit-size of 700 μm. Fig. 3(b) shows a snapshot of the atomization process of

the Co40Fe22Ta 8B30 alloy. One can observe the central stream of the molten alloy which is further spread at the intersection of the water jet (the laminar jet in the picture coming out from the left nozzle) and the Ar gas jet (invisible in the picture, coming out from the right nozzle). The powder is collected in a water-filled tank placed below the atomization point. According to DSC and XRD measurements, the spherical Co-based particle s are coated by an oxide layer. Therefore, additional manufacturing steps such as ball milling and chemical treatment (e.g. etching) are necessary to confirm amorphization of the inner core material. As a future prospect, melt-spinning will be applied to the new master alloy family,

(Co64.8B28Si7. 2 )96Hf4 and (Co68.8B25.7Si5.7)96Hf4, whose stoichiometry is attributed to the cluster line approach for the ternary Co-B-Si system. In general, hafnium is used to increase the glass-forming ability and bonding strength, however it has a high affinity to residual oxygen in the environment, as already observed by first injection/suction casting and gas atomization tests. Based on the principle from previous research works [8-10], granules or flakes made of ball-milled amorphous ribbons and gas-atomized amorphous powders can be used for different consolidation processes. Future activities will consist of hot forming and selective laser melting of Co-based feedstock to investigate the mechanical and structural properties of bulk glassy samples and composites. 38 Research Area 2 FUNCTION THROUGH SIZE

Molecular dynamics simulations of the deformation behavior BMG Crystal of metallic glass composites Many literature results in the field of BMGs and their composites were obtained upon “trial and error” methods. The INTELHYB research project aims to study in-depth the theoretica l aspects of the mechanical behavior with the help of mathematic models. Therefore special efforts are focused towards theoretical design and optimization. By computer simulations we provide detailed insights into the structure and properties of metallic glasses and composites at the atomic level. As discussed previously, in case of monolithic BMGs the plasticity is localized in a few dominant shear bands, as displayed by the red colored spots (which indicate the stress concentration) in Fig. 4(a). One of these shear bands can go critical resulting in brittle failure of the material. In order to improve the mechanical properties of metallic glasses a promising way is to form composites containing a secondary crystalline phase.

We simulated the deformation mechanism of a Cu64Zr36 metallic glass composite in form of a laminate embedded between two B2 CuZr crystalline plates which may undergo Composites stress-induced martensitic transformation. Fig. 4(b) refers to this situation. Upon tensil e deformation, above a critical stress level, the crystalline plate undergoes a martensitic transformation from B2 (blue atoms in the picture) to FCC phase (green atoms in the picture). When the crystalline plate and the metallic glass are joined together a new hybrid structure is formed, which shows a completely different mechanical behavio r (Fig. 4(c)). First, the plasticity in the glassy phase is no more localized in one dominant shear band as in the case of bulk glass. Many shear bands form (red colored spots) and they try to avoid those areas where the crystalline plates exhibit martensitic transformation (here colored in grey). In other words, there it is a strong competition between the glassy and crystalline phases to accommodate the elastic energy. Moreover, it seems that the residual elastic energy is not large enough to induce a transformation from the B2 to FCC phase as found for crystalline plates. Rather, the crystalline plates transform from the B2 to the tetragonal phase (Fig. 4(c), marked with gray spots) and Fig. 4: Molecular dynamics simulations of this transformation follows the 45 degree shearing direction. All these preliminary the deformation mechanism of a bulk result s provide clear evidence that the mechanical properties of composite materials can metallic glass (a), a B2 crystalline plate (b) and a composite structure formed by joining be tuned by controlling the crystalline fraction, phase, orientation, size, geometry, etc. both of them (c). All samples are deformed Further studies will be conducted to provide a clear understanding of the deformation in tension with a strain rate of 4 x 107 s-1 behavior of hybrid materials and to improve the ductility of this class of materials. at 50 K.

[1] M. Stoica et al., J. Appl. Phys. 115 (2014) 053520 [2] M. Stoica et al., submitted [3] D. Geissler et al. Phil. Mag. 94 (2014) 2967 [4] D. Geissler et al. Acta Mater. 59 (2011) 7711 [5] A. Kauffmann et al. Acta Mater. 59 (2011) 7816 [6] S. Pauly et al. Nature Materials 9 (2010) 473 [7] S. Pauly et al. Materials Today 19 (2013) 37 [8] J. Sort et al., Scripta Mater., 50 (2004) 1221 [9] K. B. Surreddi et al., J. Alloy. Compd. 491 (2010) 137 [10] A. H. Taghvaei et al., Acta Mater. 61 (2013) 6609

Funding: EU (ERC Advanced Grant)

Cooperation: Institute National Politechnique Grenoble (INPG), France; European Synchrotron Radiation Facility (ESRF) Grenoble, France; Deutsches Elektronen-Syn- chrotron (DESY) Hamburg, Germany; Auerhammer Metallwerk GmbH, Aue, Germany; Yonsei University, Seoul, Korea; Tohoku University, Sendai, Japan; University Vienna, Vienna, Austria Research Area 2 FUNCTION THROUGH SIZE 39

Research topic 2.3 Multifunctional inorganic nanomembranes Authors: V. M. Fomin, D. Karnaushenko, G. Lin, V. Magdanz, D. Makarov, M. Melzer, S. Sanchez, R. Schäfer, R. Streubel People involved: S. Pandey, C. Ortix, L. Ma, T. Gemming, G. Stoychev1, L. Ionov1, R. O. Rezaev2,3, E. A. Levchenko2, F. Kronast4, P. Fischer5, S.-K. Kim6, M. Kaltenbrunner7 Responsible Directors: O. G. Schmidt, J. Eckert, L. Schultz, J. van den Brink

Summary: Inorganic nanomembranes are flexible and can be transferred to virtually any substrate. This allows for transforming rigid electronic elements into their flexible counterparts with the goal to make consumer electronics thin, lightweight, and compliant. We aim at (i) understanding the electronic, magnetic, and optical properties of thin films with tunable curvature and (ii) realizing electronics with multiple diagnosti c and communication capabilities at different length scales from large area wearable electronics down to compact Lab-in-a-Tube devices.

Stimuli responsive microjets: Artficial micromotors offer great possibilities for research spanning from fundamental mechanisms of motion [1-3] at the micro-and-nanoscale to potential biomedical [4-7] and environmental applications [8-10]. In collaboration with Ionov’s group from the Institute for Polymer research, IPF Dresden, a new kind of flexible artificial micromotor was demonstrated (Fig. 1) [11]. In this case, thermore - sponsive microjets are generated from two layers of polymers (polycaprolactone and poly(N-isopropylacrylamide)) with a thin inner platinum layer which form a microtube upon release from the substrate. These self-folding micromotors move autonomously due to the catalysis of hydrogen peroxide on the platinum surface. The flexible microjets can reversibly fold and unfold by applying changes in temperature. This effect allows the microjets to rapidly start and stop multiple times by controlling the folding of the microjet. This new approach offers a convenient speed control mechanism during the operatio n of catalytic micromotors and is especially interesting for studies on bubble formation inside tubes.

Fig. 1: Flexible self-propelled microjets are formed by temperature-induced folding of thin polymer films into microtubes that contain an inner platinum layer for catalytic bubble propulsion in hydrogen peroxide. The polymer films are bilayers of an active and a passive component, which cause the microjets to fold and unfold reversibly by applying slight temperature changes. The speed control by shaping the polymeric Pt films offers a unique approach to operate this new kind of flexible bubble-propelled micromotors. The image is taken from V. Magdanz et al., Angew. Chem. 126, 2711 (2014). 40 Research Area 2 FUNCTION THROUGH SIZE

Vortex dynamics influenced by pinning centers and collective phenomena in super- Fig. 2: (a) Schematic view of an open tube. conductor microtubes: Dynamics of superconducting vortices in micro- and nanostruc- Electrodes are displayed by the heavy red lines. B is the applied magnetic field. Distribution of the tures are determined by a number of interplaying factors, including geometry, pinning squared modulus of the superconducting order centers and collective phenomena. We have demonstrated that detection of curvature parameter |ψ|2 at the magnetic flux (in units of effects on vortex dynamics [12] stays feasible in the presence of the pinning centers. The the magnetic flux quantum Φ0) Φ/Φ0 = 17. Δ impact of pinning centers on vortex dynamics on Nb superconductor open microtubes (b) Characteristic times ( t1 – the time needed for [13] (Fig. 2a) has been analyzed. Certain regions on a tube have been revealed, where a vortex to move from one to another edge and Δt2 – the nucleation period) as a function of the the presence of pinning centers is especially significant for vortex dynamics (Fig. 2b). magnetic field for a pinning center located at the The occurrence of bifurcation of the vortex trajectories is explained as a resulting effect end of the vortex trajectory. (c) Bifurcation of vortex of three factors [14]: the nucleation rate, the Magnus force and the repulsion of vortices trajectories. Distribution of |ψ|2 for the tube with μ from each other. Starting from a certain value of the magnetic field, which depends on radius R = 480 nm, length L = 3 m at the transport current density 17.14×109 A/m2 and B = 10 mT. geometrical parameters of the tube, the potential energy is lowered by changing the Solid black and dotted lines represent available vortex configuration, namely, by splitting a dense row into two sparse rows (Fig. 2c). Our vortex trajectories. The images (a) and (b) are taken results imply that superconductor open microtubes can be used as efficient vortex from R. O. Rezaev et al., Physica C 497, 1 (2014). transport elements for fluxon-based information technologies.

Imaging of buried 3D magnetic rolled-up nanomembranes: Increasing performance and enabling novel functionalities of microelectronic devices, such as three-dimensional on-chip architectures in optics, electronics and magnetics, calls for new approaches in both fabrication and characterization. Up to now, 3D magnetic architectures had mainly been studied by integral means, e.g. ferromagnetic resonance [15], anisotropic magentoresistance [16, 17], and cantilever magnetometry [18]. However, optimization of the performance of the magnetic 3D devices solely relies on precise tailoring of the local magnetic microstructures, which can barely be retrieved from integral

Fig. 3: Utilizing the shadow contrast in transmission XPEEM to visualize buried magnetic domain patterns in 3D magnetic architectures such as magnetic rolled-up nanomembranes with multiple windings. Schematic of projecting the magnetization vector field as a negative onto the planar substrate. XMCD signal is taken from experiment. The transparent non-magnetic outer layer hides the actual magnetic domain patterns from direct observation. Signal contributions from various layers can be identified. The image is taken from R. Streubel et al., Nano Lett. 14, 3981 (2014). Research Area 2 FUNCTION THROUGH SIZE 41

measurements. This goal can only be achieved by directly visualizing the magnetic domai n patterns of the complex 3D object using magnetic imaging techniques relying on magneto-optical Kerr effect [19, 20] or soft x-ray [20, 21] microscopies. Very recently, we put forth the concept to visualize magnetization patterns in 3D magnetic objects based on an advanced analysis of the shadow contrast in X-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM) accompanied by the modeling of the XMCD contrast (Fig. 3) [21]. Although we exemplarily applied it to image buried magnetic spirals prepared using rolled-up nanotechnology, the approach can be generalized to magnetic objects of virtually any shape. We discriminated mag - netic contributions from individual magnetic windings that provided means to derive the switching behavior and to reconstruct the magnetization in each layer of the magnetic spiral. Our concept can be extended to multi-component materials due to element sensitivit y of the XMCD-PEEM as well as to heterostructures of arbitrary shape. By proper engineering the magnetic microstructures in these on-chip tubular architectures potentially allows to enhance their magnetoresistive as well as magnetoimpedance performance, which is relevant for prospective magnetoencephalography [22] and memory devices [23].

Direct transfer of magnetic sensor devices to elastomeric supports for stretchable electronics: Electronics of tomorrow will be flexible or even stretchable and will form a seamless link between soft, living beings and the digital world [24, 25]. The stretchability provides vast advantages over conventional rigid electronics particularly in consume r electronics and medical implants, where large area, extreme thinness and com- pliance to curved surfaces are the key requirements for the devices [26, 27]. Introduc- ing stretchable magneto-sensorics into the family of stretchable electronics is envisioned to equip this novel electronic platform with magnetic functionalities [28-30]. Fig. 4: (a) The transferred microsensor array can conform to the soft and curved surface of a finger- Here, we introduced a novel fabrication platform for stretchable magneto-sensorics tip. The inset shows a GMR microsensor transferred relying on a single step direct transfer printing of thin functional elements from a rigid to the receiving PDMS membrane uniaxially donor substrate to a mechanically pre-stretched elastic membrane (Fig. 4) [31]. The pre-strained to 20%. GMR characteristics of method offers numerous advantages in terms of miniaturization and level of complex- (b) Py/Cu and (e) Co/Cu GMR multilayers before ity and allows transferring an entire microsensor array including contact structures in (black) and after (red) the transfer process. (c) Electron microscopy images of a cut through the a single step. Furthermore, relying on the new fabrication platform, we substantially transferred GMR film show the good adhesion of enhanced the stretchability of transferred GMR multilayer up to about 30% relying the wrinkled magnetic nanomembrane to the PDMS solely on the wrinkled topology and the meander geometry, without the formation of support. (d) A confocal microscopy image showing cracks. The latter is of great importance as the senor elements introduced here are the topology of the wrinkled GMR multilayer element. The image is taken from M Melzer et al., Adv. truly strain invariant since without cracks almost no resistance change is associated with Mat. doi: 10.1002/adma.201403998. the tensile deformation. 42 Research Area 2 FUNCTION THROUGH SIZE

Applications of the proposed technology platform are far-reaching: the presented direct transfer approach is not limited to magnetic nanomembranes, which renders possible the combination of magnetoelectronic components with other stretchable functional elements. In this way, smart multi-functional and interactive electronic systems can be envisioned for imperceptible [26] and transient [27] electronics where the magnetoelectronic components can add a sense of orientation, displacement and touchless inter - action.

[1] S. Ebbens et al., Phys. Rev. E 82, 015304 (2010). [2] L. Baraban et al., Soft Matter 8, 48 (2012). [3] J. R. Howse et al., Phys. Rev. Lett. 99, 048102 (2007). [4] D. Patra et al., Nanoscale 5, 1273 (2013). [5] J. Wang et al., ACS Nano 6, 5745 (2012). [6] A. A. Solovev et al., ACS Nano 6, 1751 (2012). [7] S. Sanchez et al., Chem. Commun. 47, 698 (2011). [8] M. Guix et al., ACS Nano 6, 4445 (2012). [9] L. Soler et al., ACS Nano 7, 9611 (2013). [10] J. Orozco et al., Angew. Chem. 125, 13518 (2013). [11] V. Magdanz et al., Angew. Chem. 126, 2711 (2014). [12] V. M. Fomin et al., Nano Lett. 12, 1282 (2012). [13] R. O. Rezaev et al., Physica C 497, 1 (2014). [14] R. O. Rezaev, E. A. Levchenko, V. M. Fomin, and O. G. Schmidt, Dynamics of Abrikosov vortices on cylindrical microtubes (unpublished). [15] F. Balhorn et al., Phys. Rev. Lett. 104, 037205 (2010). [16] C. Müller et al., Appl. Phys. Lett. 100, 022409 (2012). [17] D. Rüffer et al., Nanoscale 4, 4989 (2012). [18] D. P. Weber et al., Nano Lett. 12, 6139 (2012). [19] R. Streubel et al., SPIN 3, 1340001 (2013). [20] R. Streubel et al., Adv. Mat. 23, 316 (2014). [21] R. Streubel et al., Nano Lett. 14, 3981 (2014). [22] T. Dumas et al., PLoS One 8, e74145 (2013). [23] M. Yan et al., Phys. Rev. Lett. 104, 057201 (2010). [24] J. A. Rogers et al., Nature 477, 45 (2011). [25] S. Bauer et al., Adv. Mat. 26, 149 (2014). [26] M. Kaltenbrunner et al., Nature 499, 458 (2013). [27] S. Hwang et al., Science 337, 1640 (2012). [28] M. Melzer et al., Nano Lett. 11, 2522 (2011). [29] M. Melzer et al., Adv. Mat. 24, 6468 (2012). [30] M. Melzer et al., RSC Adv. 2, 2284 (2012). [31] M Melzer et al., Adv. Mat. doi: 10.1002/adma.201403998.

Funding: ERC Grant (#311529), Volkswagen Foundation (#86 362), DFG Priority Programme 1726, BMBF-Russia research grant (#01DJ13009), DFG Grant (#MA 5144/2-1), ERC Grant (#306277), BMBF project Nanett (German Federal Ministry for Education and Research FKZ: 03IS2011O).

Cooperation: 1IPF Dresden; 2National Research Tomsk State University, Tomsk, Russia; 3National Research Nuclear University MePhI, Moscow, Russia; 4HZB, BESSY II; 5Lawrence Berkeley National Laboratory; 6Seoul National University; 7Johannes Kepler University Linz Research Area 2 FUNCTION THROUGH SIZE 43

Research topic 2.4 Nanoscale magnets People: J. Dreiser2, A. Funk, Y. Ganushevich3, T. Greber1, S. Gómez-Ruiz4, V. Hähnel, O. Hellwig5, E. Hey-Hawkins4, L. Hozoi, D. Kasinathan10, V. Kataev, C. Konczak, J. Körner, D. Krylov, S. Kvashennikova3, V. Mehta5, V. Morozov3, O. Mosendz5, T. Mühl, V. Neu, D. Pecko6, A. Petr, D. Pohl, A. A. Popov, C. Reiche, B. Rellinghaus, M. Richter, J. Rusz7, P. Schattschneider9, H. Schlörb, O. G. Sinyashin3, C. Schlesier, S. Schneider, P. Tiemeijer8, S. Vock, D. Weller5, R. Westerström1, S. Wicht, D. Yakhvarov3, Y. Zhang, K. Zuzek-Rozman6 Responsible Directors: B. Büchner, L. Schultz, J. van den Brink

Summary: Nanoscale magnets range from single molecules to entities of a few million atoms. Due to their inherently small size and their large surface-to-volume ratio, the coupling of the magnetic cores to the local chemical environment significantly affects their magnetic moments and anisotropies. Understanding and controlling the properties of such nanomagnets at different length scales is thus at the heart of this research topic. The report reviews our work on nanoscale magnets in 2014. The materials related research on molecular magnets, magnetic nanoparticles and nanowires is com- plemented by efforts to develop novel methods and techniques which are particu - larly suited to characterizing magnetic materials at smallest possible length scales and with ultimate resolution.

Molecular magnetism

Nitride cluster fullerenes are endohedral fullerenes with triangular M3N clusters (M = Sc, Y, or lanthanides) encapsulated inside the carbon cage. In these molecular structures differen t numbers of diamagnetic (DIA) and paramagnetic (PM) ions can be combined in one cluster which allows to separate single ion properties from the influence of interactions between lanthanide ions on the magnetic properties of such molecules. We

have studied the magnetic properties of GdxSc3−xN@C80 (x = 1–3) as molecules with isotropic magnetic ions [1]. For x = 1 the magnetization follows a Brillouin curve point- ing to a negligible single ion anisotropy. For x = 1 and x = 2, however, the magnetization curves reveal ferromagnetic (FM) interactions between the Gd3+ ions with coupling strength of -1.2 K and -0.6 K for x = 2 and x = 3, respectively.

DyxSc3−xN@C80 (x = 1–3), on the other hand, exhibits single molecule magnet (SMM) behaviour [2]. Here, the nitride ion in vicinity to the lanthanide results in a large single-ion anisotropy with a uniaxial ligand field and an alignment of the magnetic 44 Research Area 2 FUNCTION THROUGH SIZE

Fig. 1: Molecular structures of DyxSc3−xN@C80 (x = 1–3) molecules (red arrows show alignment of magnetic moments along Dy–N bonds) and corresponding magnetization curves measured at 2 K.

moments along the lanthanide-nitrogen bond. As a result, DySc2N@C80 behaves as a single-ion magnet with butterfly-shape hysteresis below 5 K (cf. Fig. 1). For x > 1, exchange and dipolar interactions between the lanthanide ions strongly affect the 3+ SMM properties. While in Dy2ScN@C80, the FM coupling of Dy ions causes a broad hysteresis and large remanence, it leads to magnetic frustration and a narrow hysteresis in Dy3N@C80.

HoM2N@C80 and Ho2MN@C80 (with M = Sc, Lu, Y) were studied by NMR at room temperature [3]. Here, varying the radius of the DIA ions is found to cause a change of both the magnetic anisotropy of the Ho3+ ions and the dynamics of the clusters in the fullerene cages. In HoSc2N@C80, also a single ion magnet behaviour was determined from

AC-SQUID studies [4], albeit on a much faster time scale than in DySc2N@C80. We have also synthesized the organonickel complex [NiBr(Mes)(phen)] (1) (Mes = 2,4,6- trimethylphenyl, phen = 1,10-phenanthroline) and manipulated its magnetic properties electrochemically [5]. Electroreduction allows to switch it from DIA to PM. Surpris - ingly, in the reduced complex, the spin density is mainly located at a ligand molecule with a small leakage to the central metal ion rather than at the Ni-atom. Consequently, _ electroreduction forms a spin-radical center phen · bound to the central Ni atom, Fig. 2: Schematic view of the organonickel complex with the phenspin-radical bound to the central Ni ion which has been monitored in-situ by ESR spectroscopy (cf. Fig. 2). The magnetic _ (top), and the ESR spectrum evidencing the electro- anisotropy is enhanced with respect to the free phen · radical due to the partially un- chemical generation of the bound spin center in the quenched orbital momentum of Ni, which could be beneficial for possible applications. molecule (bottom).

Magnetic Nanoparticles in Hard Disks

Granular L10-ordered FePt films in combination with heat-assisted magnetic recording (HAMR) are expected to soon replace CoCrPt perpendicular magnetic recording films (PMR) and to provide areal storage densities (ADs) beyond 1.3 Tb/in2. To achieve this goal 3 the uniaxial anisotropy of L10-FePt (6.6 MJ/m ) has to be fully developed in the grains and the [001] easy axes have to be aligned perpendicular to the film plane. Seed layers such as TiN, SrTiO3 or MgO are needed to provide for this texture.

Fig. 3: Cross-sectional HRTEM images of three granular FePt-C samples: a) reference sample without Ar+ ion etching, b) after 4 s and c) after 10 s of irradiation. The schematic drawings on the right hand side illustrate the changes of (i) the particle morphology and structure and (ii) the number and size of second-layer particles. Research Area 2 FUNCTION THROUGH SIZE 45

(a) We have studied if and how Ar+ irradiation of the MgO seed layers helps to improve the FePt texture formation [6]. Structure and magnetic properties of the FePt-based media are characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometry (VSM). We observe a flattening of the MgO seed layer surfaces which goes along with a morphology change of the FePt grains from spherical to island-type shapes (cf. Fig. 3). This is attributed to the reduced number of nucleation sites for the FePt growth due to the smoothened seed layer surface. We also find an increased fraction of randomly oriented second layer particles and an enhanced coalescence of the FePt primary grains. These structural changes result in a reduced coercivity along the magnetic easy axis (out of plane) and an enhanced hard axis (in plane) remanence. Notwithstanding to the increased amount of coalescence, δm analysis of the magnetic interactions among the grains reveal weak dipolar couplings indicating that even the sintered grains switch as individual magnetic entities and that a treatment of the grain ensembles as Stoner-Wohlfarth systems is still permitted.

Magnetic Nanowires One-dimensional, high aspect ratio nanoscaled magnets are prepared by electrodeposition within nanoporous templates. In recent years the focus was on iron based alloys (b) with specific magnetic properties such as Fe80Ga20 showing high magnetostriction or

Fe70Pd30 exhibiting a shape memory effect. Stable electrolytic baths have been achieved by complexing the metallic components and the deposition mechanisms were investigated in detail in order to identify key deposition conditions for the reproducible preparation of homogeneous, defect free nanowires [7,8].

The as-deposited Fe70Pd30 alloy exhibits a nanocrystalline bcc phase structure but can be completely transformed to fcc as a starting point for MSM functionalization by high temperature heat treatment and subsequent quenching. Modifying the electrolyte by varying the Fe3+/SSC ratio (SSC: 5-sulfosalicylic acid, complexing agent) or addition of Cu2+ have been shown to cause a change of the structure from bcc to fcc already during deposition therefore avoiding any (unwanted) post-deposition annealing steps (cf. Fig. 4).

Quantitative MFM We developed and implemented a new measurement concept of quantitative bidirection- Fig. 4: Dependence of the FePd structure on (a) al force gradient microscopy [9] that can be directly applied to quantitative magnetic 3+ 2+ the Fe /SSC ratio and (b) the Cu ion concen- force microscopy. Quantitative force gradient measurements with cantilevers rely on the tration within the electrolyte composition. knowledge of the corresponding dynamic spring constants of the force sensor. We calculate d such dynamic spring constants for two resonant oscillation modes, which correspon d to two orthogonal oscillation directions of the probe tip, taking the spe - cific geometrical structure of our novel sensors into account (cf. Fig. 5). We proved the

Fig. 5: Probe design and corresponding modes of operation: (a) geometrical structure, (b) fundamental flexural mode for standard perpendicular force gradient microscopy (c) second flexural mode for lateral force gradient microscopy, (d) – (f) SEM images of a corresponding probe. 46 Research Area 2 FUNCTION THROUGH SIZE

applicability of the quantitative bidirectional force gradient microscopy by showing a very good agreement between force gradient measurements based on magnetostatic interactions and corresponding calculations. Furthermore, our measurement principle relies solely on flexural vibrations. This is a strong practical advantage because all microscopy modes are based on vertical probe excitation and vertical deflection measurement only and can therefore be used with common dynamic scanning force microscopy setups.

Magnetic dichroism with Electrons Similar to XMCD, electron vortex beams (EVBs), which carry quantized orbital angular moment a (OAM) L, allow to measure magnetic dichroism. Since electron beams can be easily focused to sub-nanometer diameters, this technique provides for unrivalled latera l resolution in magnetic measurements. In order to generate an EVB, specially designed apertures are needed. However, the dichroic signals to be measured with electron energy loss spectroscopy (EELS) are expected to be very small. We have successfully implemented spiral- and fork-type apertures in the condenser lens system of our FEI Titan3 80-300 transmission electron microscope (TEM) equipped with an image CS corrector. This setup allows to generate EVBs with user-selectable OAM that can be used as probes in scanning TEM (STEM). While for spiral apertures, the differen t OAM are dispersed along the beam direction, for fork-type apertures, they are dispersed in planes perpendicular to the beam. Fig. 6: (a) Spiral type and (b) fork type vortex aper- First investigations were focused on using spiral apertures, where the EVB is (de)focussed tures to be inserted into the condenser system of a to select the OAM. We have shown that the diameters of L = 0 and |L| = 1 probes are transmission electron microscope. (c) Electron vortex probes carrying orbital angular momenta of L = -1, 0.14 nm and 0.3 nm, respectively (cf. Fig. 6a/b). However, EELS did not provide any L = 0 and L = +1 as generated by using a spiral type evidenc e for dichroism in several samples, and simulations have shown that with spiral aperture. Probe diameters are roughly 0.14 nm apertures, the superposition of contributions from different OAM leads to an effective and 0.3 nm for L = 0 (central spot) and |L| = 1, cancellation of L at the sample position [10]. respectively. We have, however, found that by using fork-type apertures in combination with an additional aperture in a modified condenser setup contributions from unwanted OAM can be effectively blocked. First experiments on FePt nanocubes reveal very encourag- ing results with dichroic signals in EELS from atom-sized EVB.

[1] A. L. Svitova et al., Dalton Trans. 43 (2014) 7387-7390 [2] R. Westerström et al., Phys. Rev. B 89 (2014) 060406 [3] Y. Zhang et al., Nanoscale 6 (2014) 11431-11438 [4] J. Dreiser et al., Chem. Eur. J. 20 (2014) 13536–13540 [5] D. G. Yakhvarov et al., J. Organomet. Chem 750 (2014) 59 [6] D. Pohl et al., Ultramicroscopy 150 (2015) 16-22 [7] H. Schloerb et al., Z. Phys. Chem. 227 (2013) 1071-1082 [8] D. Iselt et al., ECS Electrochem. Lett. 2 (2013) D13-D15 [9] C. F. Reiche et al., New J. Phys., 17 (2015) 013014 [10] S. Wicht et al., J. Appl. Phys. 117 (2015) 013907

Funding: DFG: PO 1602/1-2, DFG: PE 771/4-1, DAAD project A/13/71281, Leibniz Pakt-Projekt 2014, D-A-CH: DU225/31-1, HGST Joint Study Agreement.

Cooperation: 1Univ. Zürich, Switzerland; 2Paul Scherrer Institut, Villingen, Switzerland; 3Arbuzov Institute of Organic and Physical Chemistry, Kazan, Russia; 4 Univ. Leipzig; 5HGST – A Western Digital Company, San Jose, CA, USA; 6 Jozef-Stefan Institute, Ljubljana; 7Univ. Uppsala, Sweden; 8FEI Company, Eindhoven, The Netherlands; 9TU Vienna, Austria; 10MPI for Chemical Physics of Solids, Dresden Research Area 2 FUNCTION THROUGH SIZE 47

Research Topic 2.5 Materials for energy efficiency, storage & conversion People: S.-H. Baek, J. Deng, K. Eckert 2, A. Gebert, L. Giebeler, M. Graczyk-Zajac1, H. J. Grafe, F. Hammerath, K. Hennig, M. Herklotz, T. Jaumann, F. Karnbach, M. Klose, S. Oswald, K. Pinkert, B. Rellinghaus, R. Riedel1, L. M. Reinold1, A. Surrey, W. Si, M. Uhlemann, C. Yan, X. Yang2, L. Zhang Responsible Directors: B. Büchner, O. G. Schmidt, L. Schultz, J. Eckert

Summary: Relying on the existing possibilities at the IFW to cover the complete range from developing a new material, its detailed characterization and its application in a specific device, we aim at a concerted research activity in the field of energy conversion/storage/efficiency. This activity includes development and characterization of materials for Li and Na batteries and capacitors as well as hydrogen production, storage and (re)-conversion to electricity for application on different length scales. In this report, we review our work in 2014, covering new insights into Li ion battery materials and their Li ion mobility, as well as hydrogen generation and storage applications.

Lithium dynamics in carbon-rich polymer-derived SiCN ceramics probed by nuclear magnetic resonance The performance of a Li ion battery is determined, amongst other parameters, by the Li diffusivity of its electrodes. A versatile tool to study the microscopic jump process of the Li ions is nuclear magnetic resonance (NMR). By taking advantage of the available solid-state NMR techniques at the IFW, we have determined the Li diffusion parameters over a wide dynamic range in SiCN, a polymer-derived ceramic that possess novel physica l, chemical, and mechanical features which can be tuned by subtle changes of composition and/or microstructure [1]. The slowest Li motion can be detected by 7 linewidth (FWHM) and spin-spin relaxation (T2) measurements of the Li nucleus. A -1 change in the slope of the temperature dependent FWHM and T2 indicate a crossover from the motional narrowing (high temperature) to the rigid lattice regime (low temper-

ature) which allows to determine the activation energy EA = 0.31 eV of the ionic hopping process in SiCN. Further information about the faster Li motion on a timescale of μs can -1 be obtained by measuring the spin lattice relaxation rate T1 in different magnetic fields -1 and the rotating frame relaxation rate T1ρ . The temperature and frequency dependen- cies of the 7Li relaxation rates demonstrate that the Li dynamics in the polymer-derived SiCN ceramics is governed by a stable thermal activation law opening the possibility to fine-tune the Li diffusion parameters for specific battery performance. 48 Research Area 2 FUNCTION THROUGH SIZE

Fig. 1: Properties of the nanoparticulate Si anode.

Hollow silicon nanocomposites synthesized through economical chemistry as high performance anode in Li – ion batteries Li – ion batteries are the first choice for many portable electronic devices owing to its high energy density and excellent rechargeability. Tougher requirements especially for mobile applications requires higher energy densities which can only be achieved by the development of high-capacity electrode materials [2]. Silicon is a promising candidate to replace graphite as commonly used anode with up to 10 times higher capacities owing to an alloying process of lithium with silicon. However, the large volume expansion of silicon during lithiation causes high stress inside the particles triggering crack propagatio n of individual particles causing a low cycle stability of silicon-based anodes

[3]. We developed a stable silicon anode with a high capacity of up to 2000 mAh/gSi (theoretical capacity of graphite = 372 mAh/g) which can be cycled for more than 1000 times with retaining 60 % of its capacity [4,5]. We attribute the exceptional performance to ultra-small silicon nanoparticles (< 5 nm) which do not undergo crack propagation and, even more important, form a stabilized solid-electrolyte-interface owing to its high surface energy. Additionally, a well-designed carbon cage allows good interfacial electron transfer turning the composite into a high-performance anode material. We first form a precursor through simple polycondensation of high versatile and cheap trichlorosilane with water in the presence of a surfactant followed by a temperature treatment, carbonization and an etching procedure. Current research is ongoing to optimize the silicon anode for next generation Li – sulfur batteries and to investigate structural phenomena inside the silicon anode.

Nanomembranes for energy storage in lithium ion batteries at the macro-/microscale Rolled-up nanotechnology offers an advanced strategy to deterministically rearrange two-dimensional nanomembranes into novel micro-/nanostructures for energy storage applications. Based on this technology and our previous works, we further demonstrate a hierarchical electrode design with just one material SiOx for distinct functionalitie s by controlling the oxygen content x in each layer [6]. The resulted

SiOx (x ∼ 1.85)/SiOy ( y ∼ 0.5) bilayer nanomembranes as anodes exhibit a reversible capacit y of about 1300 mAh/g at a current rate of 100 mA/g, an excellent stability of over 100 cycles, as well as a good rate capability (see Fig. 2(a)). Even after a deep cycling of 180 cycles at different current densities, the reversible capacity can recover completely to the original value at 100 mA/g. This excellent performance is due largely to the fast ionic transport, powerful strain accommodation and synergistic effect Research Area 2 FUNCTION THROUGH SIZE 49

a) b)

Fig. 2: (a) Cycling performance of both rolled-up silicon-rich monolayer and hierarchical bilayer measured at 100 mA/g for 60 cycles. (b) Schematic of an encapsulated Li-ion battery with a single silicon tube as the anode.

of oxygen-rich SiOx layer and silicon-rich SiOy layer. In order to perform a deep investigation of the electrochemical kinetics, an elegant lab-on-chip electrochemical device based on a single rolled-up Si tube is fabricated in our lab (see Fig. 2 (b)). Working as the anode in Li-ion batteries, the single tube exhibits enhanced diffusion in comparison to the planar film. After three charge/discharge cycles, the tube presents a wrinkled structure due to strain induced local deformation, which could be exploited to maintain a stable cycling and is consistent with the electrochemical performance of bulk electrodes [7]. This single tube device could be used as a promising ultra-microelectrode for other kinetic research, and an integrated full device could be developed as a local energ y supply for powering ultra-compact microsystems.

Magnetic field-driven enhancement of hydrogen production in water electrolysis The change in the German Energy Policy makes it necessary to develop novel methods for energy storage to buffer the differences between production and consumption. A highly promising way is the production of high-purity hydrogen via alkaline water electrolysis. Recently, it was shown that the efficiency of hydrogen production on planar electrodes was increased by the application of homogeneous magnetic fields normal to the electrode surface. This leads to a decrease of the bubble size and increase of the bubble release frequency and efficiency caused by magnetically induced electrolyte convections, so called magneto-hydrodynamic effect (MHD) [8]. To get a detailed understanding of the interaction of the electrolyte flow fields with the mechanism of bubble nucleation, growth and detachment, the hydrogen evolution on circular platinum micro- electrodes under the influence of homogeneous and inhomogeneous magnetic field is studied at a specifically developed electrochemical setup. The process of bubble detachment is visualized with a CCD-camera and the velocity fields are analyzed by particle image velocimetry (PIV).

Simulations on in-situ HRTEM of nanosized MgH2 at pressures of 1 bar H2 Nanostructuring of hydrides has been shown to reveal improved thermodynamic and kinetic properties, which are strongly needed for application of solid-state hydrogen

storage materials. However, most hydride phases such as MgH2 cannot be studied at highest resolution by means of TEM, because of fast degradation upon irradiation with the imaging electron beam. This can be overcome using a novel nanoreactor (see Fig. 3 (a)) recently developed by H. Zandbergen (TU Delft). It allows for in-situ TEM studies at elevate d hydrogen pressures (up to 4.5bar) and temperatures (up to 500°C). A point resolution of 1.8 Å has already been demonstrated experimentally for Cu nanocrystals. 50 Research Area 2 FUNCTION THROUGH SIZE

Fig. 3: (a) Schematic illustration of the simulated supercell representing the nanoreactor. 20 nm thick electron transparent windows composed of amorphous SiN at the top and the bottom of the nano reactor encapsulate the hydrogen gas. The MgH2 nanocrystal is placed on the bottom window. (b) Simulated HRTEM image of a 12 nm thick MgH2 nanocrystal in [110] orientation inside the nano reactor. Blue circles represent Mg atoms and orange circles hydrogen atoms.

We study the feasibility of HRTEM investigations of light weight metals such as Mg and its hydride phase with the nanoreactor by means of multi-slice HRTEM contrast simulations. Such a setup allows to fundamentally study the dehydrogenation and hydrogena- tion reactions at the nanoscale. We analyze the dependence of both spatial resolution and image contrast on parameters such as the defocus, metal/hydride thickness, hydrogen pressure and nanoreactor geometry to explore the possibilities and limitations of in-situ experiments with this reactor. Our simulations show that even for thicknesses down to 4.5 nm MgH2, atomic resolution of the crystalline specimens can be obtained.

Exemplarily, the simulated HRTEM image of a 12 nm thick MgH2 nanocrystal in [110] zone axis orientation is shown in Fig. 3 (b). The atomic structure is clearly visible even in the presence of the top and bottom SiN window and an atmosphere of 1 bar H2. The resolution is high enough to resolve neighboring Mg atom columns, which are separated by only 1.5 Å. Such simulations may be highly valuable to pre-evaluate future experiments and to design future nanoreactors.

[1] S.-H. Baek et al. Journal of Power Sources 253 (2013) 342. [2] P.G. Bruce et al. Nature Mater.11 (2012) 19. [3] C.-M. Park et al. Chem. Soc. Rev. 39 (2010) 3115. [4] T. Jaumann et al. Chem. Mater. 10.1021/cm502520y (2014). [5] T. Jaumann et al. Patent Appl. 2014. [6] L. Zhang et al. Adv. Mater. 26 (2014) 4527. [7] W. Si et al. Adv. Mater. 26 (2014) 7973. [8] J.A. Koza et al. Electrochim. Acta 56 (2011) 2665.

Cooperation: 1Technische Universität Darmstadt, Fraunhofer IWS Dresden, 2 Technische Universität Dresden, Universität der Bundeswehr München

Funding: DFG priority program SPP1473), BMBF, WING Center – Excellent battery: Batterie - Mobil in Sachsen (BaMoSa), DFG International Research Training Group (IRTG) Leibniz Pakt project Research Area 3 QUANTUM EFFECTS AT THE NANOSCALE 51

Research Topic 3.1 Designed interfaces and heterostructures People: L. Alff 3, K. Duschek, S. Fähler, J. Geck, E. Di Gennaro1, J. E. Hamann-Borrero, F. He5, N. Heming, R. Hentrich, R. Hühne, M. Knupfer, A. Koitzsch, P. Komissinskiy3, S. Krause2, K. Leistner, S. Macke4, F. Miletto Granozio1, A. Petr, G. A. Sawatzky6, H. Schlörb, U. Scotti di Uccio1, R. Sutarto5, U. Treske, M. Uhlemann, M. Vafaee3, M. Zwiebler Responsible Directors: B. Büchner, L. Schultz, J. van den Brink

Summary: With the advent of advanced deposition techniques like pulsed laser depositio n and molecular beam epitaxy it became possible to control the production of thin films and heterostructures on a level of atomic layers, thereby shifting genuine interface effects in the focus of scientific interest. Interfaces between certain complex oxides have attracted enormous attention due to the occurrence of unexpected phenomena, most notably the metallic conductivity between wide gap insulators [1]. Moreover superconductivity and magnetism have been observed [2, 3] and a variety of interface states with magnetical and orbital reconstruc- tions not stable in the bulk materials [4, 5]. These findings raise both: the prospect of stabilizing even more exotic ground states at tailored interfaces and to exploit such effects in all-oxide devices. Beyond stabilizing interesting new states, a tuning of interfac e states is pursued by studying potential dependent phenomena at the metal/electrolyte interface [6]. This approach opens the way to electric field control of magnetism in metals at room temperature - exciting for potential use in multifunctional nanosystems and magnetic data storage.

In the following we will concentrate on three examples of ongoing research activities in

the IFW concerning the interfaces between LaAlO3 and SrTiO3 and closely related

material s, the properties of LaSrMnO4 thin films on a NdGaO3 substrate and the electric field control of magnetism at an electrode/electrolyte interface.

1. Polar heterointerfaces

The LaAlO3 /SrTiO3 interface has been heavily studied during the last decade after the

discovery of the insulator metal phase transition as a function of LaAlO3 layer number. However, no consensus has been reached regarding the actual physical mechanism 52 Research Area 3 QUANTUM EFFECTS AT THE NANOSCALE

triggering the phase transition. Although the so called “polar catastrophe” scenario, Fig. 1: Full width half maximum where the metallic state is a consequence of an electronic reconstruction alleviating (FWHM) of substrat and overlayer core levels. growing internal electrostatic potentials in the overlayer, elegantly explains many experimental observations, it is steadily contested by scenarios involving point defects, such as oxygen vacancies. Our ansatz was to broaden the perspective by taking into accoun t the isostructural and isovalent NdGaO3/SrTiO3 and LaGaO3/SrTiO3 systems, which all show an insulator-to-metal transition as a function of the overlayer thickness.

The difference is the lattice mismatch between the SrTiO3 substrate and the overlayer material, which is largest for LaAlO3 and smallest for LaGaO3. We investigated the electronic properties of NdGaO3/SrTiO3, LaGaO3/SrTiO3, and LaAlO3/SrTiO3 in a comparative study based on X-ray absorption spectroscopy, X-ray photoemission spectroscopy and resonan t photoemission spectroscopy. Furthermore, LaVO3/SrTiO3 interfaces were prepare d for future investigations exhibiting a similar sharp insulator-metal phase transition at 6 monolayers. First the nature of the charge carriers, their concentration and spatial distribution have been studied and quantitatively evaluated. The charge carriers are of Ti 3d character and the 2-dimensional sheet carrier density has a lower boundary in the range of 0.8 – 1.5 x 1014 cm-2 in reasonable agreement with Hall conductivity data. The extension of the charged near interface region must be at least 2 nm. Fig. 1 shows a compilation of the peak width of several core levels divided into substrate and overlayer excitations.

Fig. 2: Band diagram of polar heterostructures derived on the basis of photoemission data. Research Area 3 QUANTUM EFFECTS AT THE NANOSCALE 53

Fig. 3: Structure of an LaSrMnO4 film on an NdGaO3 substrate.

Clearly the overlayer lines have a tendency to decrease with layer number. This is not expected for the polar catastrophe model: the increasing electrostatic potentials would cause a line broadening. On the other hand a broadening is observed for the SrTiO3 lines. From this and other measurements (exploiting the peak positions) a band diagram could be extracted (Fig. 2). The behavior of the three analyzed heterostructures is found to be remarkably similar.

The valence band edge of all the three overlayers aligns to that of bulk SrTiO3. The con- duction band offset differs due to the different gap values among the materials. The near- interface SrTiO3 layer is affected, at increasing overlayer thickness, by the building-up of a confining potential. This potential bends downwards both the valence and the con- duction band, the latter one crossing the Fermi energy in the proximity of the interface, and determines the formation of an interfacial band offset growing as a function of thickness. In this way a metallic interface region emerges. Quite remarkably, but in agreement with previous reports for LaAlO3 /SrTiO3, no electric field is detected inside any of the polar overlayers. Especially the last point poses a serious obstacle for the polar catastrophe model in its original form. A possible way to circumvent this problem is the assumption that oxygen vacancies are created during the film growth and the subsequent charge transfer balances internal fields.

2. Manganate layers For interfaces and thin layers the determination of important structural information such as interface terminations and stacking of atomic layers is often difficult. Here a scheme based on resonant x-ray reflectivity measurements is developed which is capable to provide such information with atomic resolution. Using LaSrMnO4 as an example the theoretica l and experimental implications of this approach are explored. In simple words, the reflectivity is given by interference of x-rays that are reflected at the different interfaces realized in an artificial heterostructure. Referring to the reflection of optical light, an interface can be defined as a region in space where there is a change of the refractive index n. Similarly, also in the x-ray range even a small change in n will introduce an interface, thus a traveling x-ray wave will be reflected. This high interface sensitivity is what allows to accurately determine structural properties of heterostructures such as layer thicknesses and interface roughnesses by means of x-ray reflectivity. Going one step further at synchrotron light sources the reflectivity can be studied by tuning the x-ray photon energies to an absorption edge. At these so-called resonant energies, the refractive index depends very strongly on the valence shell configuration of the resonant scattering centers and, hence, the sensitivity to spatial variations of the electronic properties is dramatically enhanced at resonances.

By quantitatively modelling experimental reflectivity data of LaSrMnO4 we obtained detaile d information of the film structure as exemplified in Fig. 3. Resonant x-ray scatterin g will be a powerful tool for the investigation of a broad class of artificial heterostructure s. 54 Research Area 3 QUANTUM EFFECTS AT THE NANOSCALE

3. Electric field control of magnetism at the electrode/electrolyte interface Electric control of magnetism is a vision which drives intense research on magnetic semiconductors and multiferroics. Recently, also ultrathin metallic films were reported to show magnetoelectric effects at room temperature [6]. We study electric field induced changes of magnetism at the electrode/electrolyte interface. This approach allows to exploi t potential dependent electrode processes as double layer charging, and/or faradaic reactions to control the surface magnetism. We achieved significant changes of anisotropy, coercivity and magnetization in FePt and CoPt. For Fe films, faradaic reactions involving Fe and iron oxide have been investigated and a reversible in- and decrease of saturation magnetization up to 64 % was achieved (Fig. 4). This opens the way to voltage controlled “on/off” nanomagnets. In a next step such a switchable surface Fe layer has been combined with a textured hard magnetic FePt layer. In this case, by exchange coupling through the interface, voltage control of the overall spin orientation has been achieved.

Fig. 4: Voltage induced change of magnetization in Fe films probed by in situ Anomalous Hall Effect measurements.

[1] A. Ohtomo et al., Nature 427, 423 (2004) [2] N. Reyren et al., Science 317, 1196 (2007) [3] A. Brinkman et al., Nature Materials 6, 493 (2007) [4] J. Chakhalian et al., Science 318, 1114 (2007) [5] A. Tebano et al., Phys. Rev. Lett. 100, 137401 (2008) [6] M. Weisheit et al., Science. 315, 349 (2007)

Funding: DFG Emmy Noether Program, DFG Eigene Stelle

Cooperations: 1 Univ. Naples, Italy; 2 BESSY, Berlin, Germany; 3 Univ. Darmstadt, Germany; 4 UBC Center, Vancouver, Canada; 5 Canadian Light Source, Saskatoon, Canada; 6 Univ. British Colombia, Canada Research Area 3 QUANTUM EFFECTS AT THE NANOSCALE 55

Research topic 3.2 Self-organised electronic order at the nanoscale Authors: J. Geck, T. Ritschel, J. Trinckauf, K. Koepernik, M. Daghofer, L. Hozoi, S-H. Baek, D. V. Efremov, R. Ganesh, S. Sykora, P. Abbamonte1, H. Berger2, J. J. Betouras3, X. M. Chen1, T. C. Chiang1, A. V. Chubukov4, S. L. Cooper1, K. D. Finkelstein5, E. Fradkin1, Y. Gan1, G. Garbarino6, P. Ghaemi1, M. Hanfland6, D. G. Hawthorn7, F. He8, Y. I. Joe1, M. Kawasaki9, J. S. Kim10, J. C. T. Lee1, G. J. MacDougall1, M. Nakamura9, J. M. Ok10, G. A. de la Peña1, G. A. Sawatzky11, E. Schierle12, R. Sutarto11, Y. Tokura9, H. Wadati13, S. Yuan1, M. v. Zimmermann14 People involved: D. Baumann, C. Blum, S.-L. Drechsler, D. V. Efremov, H.-J. Grafe, C. Hess, R. Hübel, M. Knupfer, M. Kusch, S. Leger, U. Roessler, F. Steckel, S. Sykora, S. Wurmehl, M. Zwiebler Responsible Directors: B. Büchner, J. van den Brink

Summary: The objective of this research focus is to investigate self-organization phenomen a in complex electron systems with pronounced electron-electron and electron-phonon interactions. The large families of transition metal oxides and transition metal dichalcogenides as well as the iron pnictides provide prime examples for materials, which realize such electron systems and which are also studied here. The present research effort takes great profit from the unique combination of comple - mentary methods available at the IFW Dresden and as such merges state-of-the-art theoretical methods with leading-edge experiments. In this report, we focus on a specific highlight of our work in 2014, namely the relation between superconductivity and electronic order in real space as well as the emergence of complex orbital textures in transition metal dichalcogenides.

A great variety of interacting electron systems spontaneously form intrinsic electronic nanostructures, typically driven by strong electron-electron and electron-phonon interactions. The microscopic structure of such an electronic order is therefore a direct fingerprint of the relevant interactions in a system as well as the involved degrees of freedo m. In addition to this, self-organized electronic orders are intensively discussed in relation to the most fascinating electronic phenomena we know today, like uncon - ventional superconductivity, colossal magnetoresistance, strong magnetoelectric coupling s or quantum criticality.

A strong motivation for the study of self-organized electronic orders is therefore to unrave l the microscopic physics behind these phenomena. This is not only of great interest for basic research. It also bears relevance for applied science, since the 56 Research Area 3 QUANTUM EFFECTS AT THE NANOSCALE

understanding of the microscopic mechanisms at work may also show up routes towards new technological applications. It is also very important to point out that recent advances in experiment and theory nowadays make it possible to probe, manipulate and analyze these electronic ordering phenomena in unprecedented detail. A famous case in point here are the magnetic skyrmions, which were first predicted by theory, then observed by momentum resolved experiments and, just in 2013, manipulated using spatially resolve d scanning microscopes.

Notwithstanding these recent breakthroughs, we are only beginning to understand electronic order in complex materials and many important aspects still remain to be explored. Within this research topic we merge the unique expertise of the IFW in materials preparation (bulk, thin films, heterostructures and lateral nanostructures), experimental characterization (thermodynamics, scanning probes, x-ray spectroscopies, x-ray scattering, photoemission) and theoretical modeling (ab initio and model-based) into one coherent research effort. Central aim is to understand the coupling between electronic ordering in real space on the one hand and the electronic structure on the other hand. In this way, the present topic builds a bridge from fundamental research towards applications. The activities within this research focus are also part of the new Collabo- rative Research Center in Dresden (SFB 1143) and the Graduate School (GRK 1621) at the Technical University of Dresden.

During 2014, a number of complex electron systems displaying unconventional types of electronic order have been investigated, including iron pnictides [1], uranium-based heavy fermion compounds [2], bulk and nanostructures of transition metal oxides [3] and various transition metal dichalcogenides [4]. In this report, however, we will focus on new results regarding the electronic order in 1T-TaS2 and 1T-TiSe2, which illustrate how the strategy for this research focus has already put into practice

1T-TaS2 and 1T-TiSe2 exhibit a number of charge density wave (CDW) phenomena that attract considerable attention, in particular because these electronic orderings occur in close proximity to superconductivity (SC). In fact, we found strong evidence that defects within the electronic superlattice formed by the CDW are essential to create superconductivity: Using high-pressure X-ray diffraction (XRD) experiments, we discovered a superconductin g electronic crystal in 1T-TaS2 that is characterized by a long-range order of solitonic defects within a CDW-superlattice.

Fig. 1: Pressure–temperature phase diagram of

1T-TiSe2. a) Broad phase diagram showing CDW ordered, normal state and superconducting phase boundaries. The green color scale indicates the integrated intensity of CDW peaks, including both

the C and IC components. The superconducting TC, has been exaggerated by a factor of five for visibility. Points where the precise commensurability was measured are labelled C, I or C/I, indicating commensurate, incommensurate or coexistence, respectively. Ordered CDW-defects occur within the I-phase. b) Zoom-in on the region exhibiting the transition between commensurate and incommensurate order (grey dashed rectangle in a). From Ref. 5. Research Area 3 QUANTUM EFFECTS AT THE NANOSCALE 57

To better understand the connection between SC and such defects, we extended our investigation s and used high-pressure XRD to directly study the CDW order in 1T-TiSe2 [5], which was previously shown to exhibit SC when the CDW is suppressed by pressure or intercalation of Cu atoms. As shown by the phase diagram in Fig. 1, we succeeded in suppressing the CDW fully to zero temperature, establishing for the first time the existence of a quantum critical point at Pc = 5.1 ± 0.2 GPa, which is more than 1 GPa beyond the end of the superconducting region. Unexpectedly, at P = 3 GPa we observed a reen- trant, weakly first order, incommensurate phase, indicating the presence of a Lifshitz tricritical point somewhere above the superconducting dome. This study suggests that superconductivity in 1T-TiSe2 is not connected to the quantum critical point itself. It rather further supports the notion that the formation of defects within the CDW order plays an important role for SC in the transition metal dichalcogenides.

In a very recent work, also done during 2014, we further found that CDW order in transition metal dichalcogenides does not only involve charge modulations. Instead we revealed a remarkable and surprising new feature of CDWs, namely their intimate relation to orbital order. Combining state-of-the-art density functional theory with leading-edge x-ray scattering and photoemission experiments, we not only showed that the CDW of

1T-TaS2 within the two-dimensional TaS2-layers involves previously unidentified orbital textures of great complexity. We also demonstrated that two metastable stackings of the orbitally ordered layers allow manipulating salient features of the electronic structure.

As can be seen in Fig. 2, for both metastable stackings a complex orbital texture within the ab-plane emerges. Note that not only the occupancy of a certain type of orbital changes spatially, but also the symmetry of the orbitals clearly changes from site to site, resulting in a complex orbital ordering pattern. For instance, whereas the orbital is oriente d perpendicular to the ab-plane at the center of a Ta-cluster, a significant in- plane component exists at the cluster edges. It is also worth mentioning that the in-plane orientation of some orbitals changes as a function of the c-axis stacking and that also the S 3p-states take part in the orbital texture.

Fig. 2: Real space illustration of the electron density for the highest occupied band of the

CDW phase of 1T-TaS2. (a), (b): A complex orbital texture emerges within the ab-plane. (c): The 1c-stacking allows for significant hopping only along the c-direction. (d): A substantial ab-component of the hopping appears for the 2a+c-stacking, which is metastable with the 1c stacking in (c). 58 Research Area 3 QUANTUM EFFECTS AT THE NANOSCALE

The orbital stacking illustrated in Figs. 2(a,c) permits significant charge hopping only along c. In other words, the charges flow along orbital stripes along c, corresponding to the quasi one-dimensional character of the uppermost band close to the Fermi level. This drastically changes in the case of the stacking shown in Figs. 2(b,d). Now there is a significant ab-component of the hopping, so that the uppermost band attains a larger in-plane dispersion and crosses the Fermi level along Γ-M and Γ-K (not shown).

Based on these new insights from basic research, a new device concept has been develope d, which we termed orbitronics. The orbital effects described above enable to switch the properties of 1T-TaS2 nanostructures from metallic to semiconducting with technologically pertinent gaps of the order of 200 meV, as shown in Fig. 3 for a 1T-TaS2 bilayer. This new type of orbitronics is a good example of how basic research can lead to new technological concepts, which is especially relevant for the ongoing development of novel, miniaturized and ultra-fast devices based on layered transition metal dichalco- Fig. 3: Device concept based on the switching genides. between metastable orbital orders. Calculated band

structure for a bilayer of 1T-TaS2 with 1c-stacking (a) and 2a + c-stacking (b). A semiconductor-to-metal [1] S.-H. Baek et al., Nature Materials, advance online publication (2014) transition takes place upon changing the stacking of [2] A.V. Chubukov et al., Phys. Rev. Lett. 112, 037202 (2014) the two layers. (c): Orbital order corresponding to [3] H. Wadati et al., New Journal of Physics 16, 33006 (2014) the semiconducting (top) and metallic state (bottom). [4] R. Ganesh et al., Phys. Rev. Lett. 113, 177001(2014) [5] Y. I. Joe et al., Nature Physics 10, 421 (2014)

Funding: Deutsche Forschungsgemeinschaft

Cooperations: 1Department of Physics and Frederick Seitz Materials Research Labora- tory, University of Illinois, Urbana, USA; 2Ecole Polytechnique Federale de Lausanne, Switzerland; 3Department of Physics, Loughborough University, United Kingdom; 4Department of Physics, University of Wisconsin-Madison, USA; 5Cornell High Energy Synchrotron Source, Cornell University, Ithaca, USA; 6European Synchrotron Radiation Facility (ESRF) Grenoble, France; 7Department of Physics and Astronomy, University of Waterloo, Ontario, Canada; 8Canadian Light Source, University of Saskatchewan, Canada; 9RIKEN Center for Emergent Matter Science (CEMS), Japan; 10Department of Physics, Pohang University of Science and Technology, Korea; 11Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada; 12Helmholtz-Zentrum Berlin für Materialien und Energie, Germany; 13Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Hongo, Japan; 14Deutsches Elektronensynchrotron (DESY), Hamburg, Germany Research Area 3 QUANTUM EFFECTS AT THE NANOSCALE 59

Research topic 3.3 Quantum and nano-photonics Authors: S. Böttner, Y. Chen, F. Ding, S. Giudicatti, B. Höfer, Y. Huo, M. R. Jorgensen, A. Madani, S. M. Marz, E. Zallo, J. Zhang, M. Zopf People involved: R. Hühne, M. Mietschke, C. Ortix Responsible Directors: O. G. Schmidt, L. Schultz, J. van den Brink

Summary: Next-generation photonic devices will rely on an ever increasing ability to route, trap, and otherwise manipulate light under tight tolerances. For example a precise control of the light emission wavelength is vital for the applications of single or entangled photons in quantum information sciences. Another example is the enhanced light-matter coupling in an optical resonator with tailored light trapping, which is central to a variety of exciting optoelectronic device concepts. In this context we have developed nanomembrane based technologies to manipulate light at micro- and nanoscales. Two photonic devices from our most recent progresses will be discussed in this review. The first is an on-demand and wavelength tunable single photon source, based on the light-hole emission from GaAs quantum dots embedded in a strain engineered membrane. The second is a microtube resonator fabricated with rolled-up titania nanomembranes, which has an optical resonance in the visible range.

Manipulation of light with nanomembrane technologies Part I: Self-assembled quantum dot (QD) based SPSs are one of the promising candidates for photonic quantum interface applications, with which the polarization state of singl e photons and the electron spin states can be coherently interconverted. By em - ploying the large discrepancy between the g-factors of electrons and light holes (LHs) confined in a semiconductor QD, it is possible to realize bidirectional interconversion between the states of single stationary (spin) and flying qubits (photon).

We reported on-demand and wavelength-tunable LH single-photon emission from tensile-strained GaAs QDs embedded in nanomembranes [1]. The former property confirms the zero-dimensional character of our emitters, while the latter allows interfacing differen t QDs for remote entangling electron-spins. First we present the experimental methods of generating LH emissions from GaAs QDs. Then we demonstrate triggered LH 60 Research Area 3 QUANTUM EFFECTS AT THE NANOSCALE

single-photon emission in the second-order time correlation measurements. We also show that the emission wavelength of LH single photons can be dynamically and precisely tuned in a wide range by means of an externally-induced strain field.

The sample studied in this work consists of GaAs/AlGaAs QD heterostructure embedded in two pre-stressed InAlGaAs layers, and was grown by solid-source molecular beam epitax y (MBE). It includes a 140 nm-thick QD-containing nanomembrane on top of a

100 nm-thick Al 0.75Ga0.25As sacrificial layer. In situ Ga droplet etching was used to 8 -2 grow GaAs QDs in Al xGa1-xAs barriers (dot density < 10 cm ). In particular, the sample structure was designed in such a way that GaAs/Al xGa1-xAs QDs layer is sandwiched betwee n a pair of 20 nm-thick In0.2Al0.4Ga0.4 As stressor layers. After removal of the sacrificial layer in diluted HF solution, the compressed stressor layers expand inducing an in-plane (xy plane) biaxial tension of about 0.4% to the GaAs QDs. This feature results in the switching of the hole GS from a dominant HH character to a dominant LH character [1]. Thereafter, the free-standing QDs nanomembranes were transferred onto a 200 μm-thick piezoelectric crystal [Pb (Mg1/3Nb2/3)O3]0.72[PbTiO3]0.28 (PMN-PT) via Au-to-Au thermo-compressive bonding as illustrated in Fig. 1a. When an electric field Fp (//z) is applied to the PMN-PT, an in-plane biaxial stress field from the PMN-PT actuator is applied to the QDs nanomembranes. This allows for a precise tuning to the emission wavelength of single photons emitted by the LH-excitons, see the upper inset of Fig. 1b

Of most interest is the pulsed optical operation of our device. This allows controlling the Fig. 1: (a) A sketch of the nanomembrane-based time of generation of excitons, and thereby realizing triggered LH single-photon emis- strain-tunable LH emissions. The GaAs nanomembrane including GaAs QDs integrated onto a piezo- sion. In order to achieve this, the diode laser is used to drive the QDs and meanwhile electric crystal, in which the strain field can modify the second-order time correlation function is measured under pulsed excitation. The the emission energy of photons emitted from the lower inset of Fig. 1b shows the unnormalized autocorrelation function of the in-plane QDs. (b) Wavelength tuning of the LH single-photon polarized exciton emissions, and the quantum nature of LH single-photon emission is emission as a function of Fp. A positive (negative) revealed by the significantly suppressed peak at zero-time delay. In addition, periodic electric field corresponds to a compressive (tensile) strain field. The lower inset shows an autocorrelation peaks in the autocorrelation measurement are observed. This is an unambiguous signa- measurement. ture of a triggered LH single-photon emission. The temporal distance between these peaks is found 12.5 ns, which is consistent with the excitation repetition rate of the diode laser, 80 MHz.

One of the most important elements for a LH-based reversible quantum interface is a ‘tuning knob’ for the ground state energy levels of different QDs, which facilitates the direct state transfer from the photon qubit emitted by one QD to the electron qubit in another QD. Such a tunability is demonstrated with our LH QDs in Fig. 1b. A non-zero Research Area 3 QUANTUM EFFECTS AT THE NANOSCALE 61

electri c field Fp is applied to the PMN-PT actuator to generate an in-plane strain field on the QDs and a series of PL spectra from the QD are recorded as a function of Fp. Compared to the emission wavelength at Fp = 0 kV/cm, the LH single-photon emission can be blue- shifted (red-shifted) when a positive (negative) electric filed is applied. The total wavelength has been tuned by 3 nm (6 meV in energy) as Fp is varied from -20 to 40 kV/cm. These results indicate that the optical properties of our LH single photon source can be accurately tuned, and stable single-photon emission during the tuning process is preserved.

Part II: Recently vertically rolled-up microcavities (VRUMs), as a novel form of whisper- ing gallery mode (WGM) resonators, have attracted great interest and accordingly opened up several attractive applications thanks to advances in rolled-up nanotech - nology. Key features of VRUMs include the capability of on-chip fabrication, the hollow core structure, and their ultrathin walls, which facilitate a highly penetrating evanes- cent wave sensitive to changes in the ambient refractive index. Depending on conditions, VRUMs can be structurally robust enough to be transferred onto foreign substrates. For these reasons, VRUMs are promising candidates for specialized tasks in integrated optic s, optoelectronics, and lab-on-a-chip applications. Recently, we reported the inclusio n of titania into the pallet of materials available for VRUMs.[3] Titania, as a materia l, is an excellent candidate for optical devices due to its high refractive index while maintaining transparency through the visible. In combination with the fabrication strategies available using rolled-up nanotechnology, a wealth of optical structures with improved properties is possible. However, titania is still new to rolled-up nanotechnology and a considerable amount of effort has been required to optimize processes for this material.

We presented a systematic work on the fabrication and characterization of titania microtube s as an active material for different potential applications.[4] We showed how titania microtubes can be rolled up using different sacrificial layers and discussed the possibility of controlling not only geometrical characteristics but also the physical Fig. 2: (a – c) SEM images showing rolled-up TiO2 properties such as the crystalline phase. The structural and optical properties of titania tubes using square, circular and U-shape patterns. deposited under different deposition conditions were investigated on single titania In all the cases, titania membranes deposited at membranes deposited on silicon substrates. room temperature were rolled using a photoresist sacrificial layer. (d–f) Dependence of the tubes diameter on the titania membrane thickness for Titania microtubes can be successfully rolled up starting from different shapes and sizes the different patterns presented in panels (a–c). of the pattern, for example square, circular and U-shape masks (Fig. 2). The square and 62 Research Area 3 QUANTUM EFFECTS AT THE NANOSCALE

circular patterns usually result in a higher yield (close to 100%) as previously reported for SiO2. On the other hand, the U-shape offers interesting opportunities in the design of optical resonators, since it avoids light leakage where the center of the tube is lifted from the substrate and facilitates axial confinement of light.

Optical characterization of resonant modes at telecom wavelengths was performed on U-shaped titania VRUMs by interfacing with a tapered fiber. Polarized light from a tunable IR laser was coupled into the fiber, and subsequently into the VRUM. Resonant modes are manifested by a sharp decrease in transmission through the fiber. By scanning the position of the fiber along the tube axis, controlling the angle that the fiber intersects the tube, and varying the polarization through the fiber, the coupling can be optimized. Figure 3 shows a representative transmission signal from a titania VRUM rolled-up from a U-shaped pattern following optimization of fiber coupling. Fiber coupling can be extended to create polarization-resolve mode maps that provide insight into the nature of light-matter interactions within rolled-up resonators. These experiments have been done in detail on HfO2 coated silica tubes, leading to the observation of new optical modes as well opening the door to interesting utilizations.[5, 6]

Fig. 3: Normalized fiber transmission signal while coupled to the center lobe part of one of the thicker ends. Multiple resonance modes are visible. Calculated mode positions are indicated by red triangles. Inset: the fundamental modes have a fine splitting with Q factors up to 7.7 × 103.

The combination of titania with rolled-up nanotechnology presents many interesting opportunities for novel applications. Control over the structural and optical properties of rolled-up titania microtubes has been achieved by means of a proper tuning of the fabrication parameters. Optical characterization using tools such as polarization-resolved near-field maps of optical modes allow us to probe rolled-up resonators, providing feedback for fabrication improvements, leading to application.

Acknowledgements: We thank B. Eichler, R. Engelhard and S. Baunack for the technical support, also D. Grimm, B. Martin and S. Harazim for assistance in clean room main - tenance. Collaborations with R. Hühne and C. Ortix are important to our ongoing and future projects.

[1] J. Zhang et al., Nano Lett., 15 (2015), 422. [2] Y. Huo et al., Nature Phys. 10 (2013) 46. [3] A. Madani et al., Opt. Lett. 2013, 39 (2), 189-192. [4] S. Giudicatti et al., J. Mater. Chem. C 2014, 2 (29), 5892-5901. [5] S. Böttner et al., App. Phys. Lett. 2014, 105 (12), 121106. [6] J. Trommer et al., Opt. Lett. 2014, 39 (21), 6335-6338.

Cooperation: Johannes Kepler University Linz, Austria Funding: BMBF project QuaHL-Rep, EU project HANAS, China Scholarship Council Research Area 3 QUANTUM EFFECTS AT THE NANOSCALE 63

Research Topic 3.4 Functional molecular nanostructures and interfaces Authors: Y. Zhang, A. Svitova, C. Schlesier, K. Junghans, Q. Deng, N. Samoylova, A. A. Popov People involved: A. Beger, A. Brandenburg, Q. Deng, E. Dmitrieva, D. Krylov, M. Rosenkranz, S. Schiemenz, C. Schlesier, F. Ziegs Responsible Directors: B. Büchner, O. G. Schmidt, J. Eckert

Summary: Recent studies of endohedral metallofullerene synthesis and electron trans-

fer properties in IFW are reviewed. The first endohedral fullerene structure LaSc2N@C80 with heptagon is synthesized and characterized. High thermodynamic stability and low

yield of LaSc2N@C80-Cs(hept) show that fullerene formation is not fully controlled by thermodynamic factors. New type of clusterfullerenes with two lanthanide ions, cen-

tral carbon atom and Ti = C double bond (e.g. Lu2TiC@C80) is discovered and conditions for a highly selective synthesis of such species are revealed. A plethora of endohedral metallofullerenes with cluster-based redox activity and the mechanism of their redox reactions is described.

Endohedral metallofullerenes: new cages, clusters, and electron transfer phenomena Endohedral metallofullerenes (EMFs) are hollow-shaped carbon cages encapsulating metal ions or cluster in their inner space [1]. By virtue of such hybrid structure, chemical and physical properties of EMFs are determined by (i) the fullerene cages, (ii) endohedral species, and (iii) by the phenomena resulting from the mutual interactions of the carbon cage and encapsulated cluster. All these aspects should be therefore carefully explored.

Various carbon cages have different π-system topology, which in due turn varies the frontie r molecular orbital energies and their spatial distribution. Besides, geometrical properties of the σ-carcass (e.g. its size and shape) have crucial influence on their ability to form endohedral fullerenes [2]. Hence, the study of the possible fullerene cages and their role in EMF formation is an important aspect of the EMF research. According to the IUPAC definition, fullerenes are “Compounds composed solely of an even number of carbon atoms, which form a cage-like fused-ring polycyclic system with twelve five- membered rings and the rest six-membered rings”. The heptagon-containing fullerenes have been studied theoretically and were found less stable than conventional 64 Research Area 3 QUANTUM EFFECTS AT THE NANOSCALE

pentagon/hexagon cages, and hence their formation in a standard arc-discharge synthesis has never been observed. The synthesis of nitride clusterfullerenes usually yields two isomers with the C80 cage that dominate in the M3N@C2n fullerene mixture [1].

The most abundant isomer has Ih cage symmetry, whereas the second most abundant structure is the isomer with the D5h cage. However, our recent study of the mixed- metal La-Sc system revealed formation of the third isomer of LaSc2N@C80, whose structure was elucidated by single-crystal X-ray diffraction [3]. The new EMF structure has 13 pentagon and is the first example of an EMF molecule with a heptagonal ring (Fig. 1).

Computational DFT study shows that LaSc2N@C80 with heptagonal ring is almost as stable as the Ih cage isomer, which refute the claims on the low stability of heptagon- containing fullerenes. If the isomeric distribution would be governed by the thermo - dynamic stability, a much higher yield of the heptagon-containing isomer might be expecte d. However, experimental studies contradict this expectation. The reason for the low yield of heptagonal fullerenes may be in the kinetic factors, i.e. the ease of the structura l rearrangement to other fullerene cages. Comparison of the C80-Cs(hept) and the most abundant C80-Ih cage isomers reveals their close similarity. These two structures are related by a single Stone-Wales transformation, i.e. a “rotation” of the C2 fragment highlighted in light green in Fig.1 by 90°and corresponding readjustment of the σ-cage network. The barrier towards such rearrangement of ca 6.5 eV is rather high for a room temperature but can be easily accessible in the hot carbon arc during the fullerene formation.

The mutual stabilization of the cage and endohedral species is well understood based on the metal-to-cage electron transfer, but prediction of the structures of possible endohedral cluster remains a challenging problem. A plethora of metal or hybrid metal/non- metal clusters has been already encapsulated within the carbon cage, and new examples of species capable of forming the EMFs molecules are continuously reported. Choosing the type of clusterfullerene to be formed and a metal or a combination of metals to be encapsulated the electronic and magnetic properties of EMFs can be varied in a broad range. Hence, exploration of the species which can be encapsulated into the carbon cage during the EMF formation is another important aspect of the EMF research, where serendipity plays an important role. In an attempt to synthesize of the mixed-metal

Ti-Lu nitride clusterfullerenes by the arc-discharge with NH3 reactive gas atmosphere our Fig. 1: Molecular structures of LaSc2N@C80 isomers group recently discovered formation of the new type of clusterfullerenes, in which the with C80 - Cs (hept) (top) and C80 -Ih (bottom) cage central atom is carbon making a double bond to a titanium atom and single bonds to two isomers (Sc atoms are magenta, La is orange, and N is blue). The cage fragment near the heptagon is lanthanide ions (Fig. 2) [4]. In fact, the structure of Lu TiC@C is very similar to that 2 80 highlighted in red, the C-C bond which is “rotated” of Lu2ScN@C80, to which it is isoelectronic. Further exploration of reaction conditions in the Stone-Wales rearrangement is highlighted in revealed that Ti-carbide clusterfullerenes can be obtained with high selectivity by light green. introducin g methane CH4 into the arc-discharge generator.

Fig. 2: Molecular structure of Lu2TiC@C80 determined by single crystal X-ray diffraction and schematic description of endohedral

clusters in Lu2TiC@C80 and Lu2ScN@C80. Research Area 3 QUANTUM EFFECTS AT THE NANOSCALE 65

Irrespective of the endohedral cluster composition, all EMFs have one common element – the metal/π-system interface. Behaviour of this interface under electron transfer conditions has been thoroughly studied by electrochemistry and spectroelectrochemistry. While the carbon cage is the only redox-active center in empty fullerene, in EMFs both the fullerene cage and the endohedral species can be redox active. Of particular interest are EMFs exhibiting endohedral redox activity. In such processes, the fullerene cage merely acts as an inert container, transparent to electrons and stabilizing the variable

spin and charge state of endohedral species [5]. Lu2TiC@C80 is an illustrative example

of such EMF: its LUMO is to a large extent localized on Ti ion, and reduction of Lu2TiC@C80 proceeds via the change of the Ti valence state. On the contrary, reduction of isostruc-

tural and isoelectronic Lu2ScN@C80 is a cage-based process and is shifted to a more negative potential range by 0.51 V [4].

Unique redox behaviour of endohedral CeIII ion is found in cerium-based nitride cluster- III fullerenes such as CeM2N@C80 (M = Sc, Y, Lu) [6]. Due to the large ionic radius of Ce (1.01 Å), encapsulation of Ce-based nitride clusters within medium-size carbon cages result s in the significant inner strain. Oxidation of CeIII via removal of the 4f electron forms CeIV with much smaller ionic radius (0.87 Å), and therefore strained Ce-based EMFs are prone to oxidation as a way to release the strain. The Ce-based oxidation of such EMFs

can be proved by NMR spectroscopy as exemplified in Fig. 3 for CeSc2N@C80: formation IV + 13 45 of the diamagnetic [Ce Sc2N@C80] cation results in the shift of C and Sc NMR III resonance lines in comparison to the paramagnetic Ce Sc2N@C80. Variation of the

CeM2N cluster by choosing the metal M of different size (Sc, Lu, Y) modifies the inner strain and therefore changes oxidation potential of the endohedral CeIV/CeIII pair. On the other hand, variation of the carbon cage also results in the changes of the inner

strain. A systematic study of CexM3−xN@C2n with different cage size (2n = 78–88) showed that the oxidation mechanism of these molecules is governed by a subtle balance between the cluster and the cage size [7].

Fig. 3: Top: 13C and 45Sc NMR spectra of + CeSc2N@C80 and [CeSc2N@C80 ] . Bottom: change of the cluster shape in

CeY2N@C80 from highly strained pyramidal to planar induced by oxidation. 66 Research Area 3 QUANTUM EFFECTS AT THE NANOSCALE

Sc3N@C80 is an example of endohedral redox activity with Sc3N-based reduction. Chemical derivatization such as cycloaddition changes the π-system of the fullerene and hence can substantially affect the electrochemical properties of Sc3N@C80. Sc3N@C80 has two types of CC bonds located at pentagon/hexagon [5,6]) and hexagon/hexagon

[6,6] edges. The anion radicals of isomeric [5,6] and [6,6] Sc3N@C80 benzoadducts were studie d by electron spin resonance spectroscopy [8]. In both compounds the rotation of the Sc3N cluster is frozen and the spin density distribution of the cluster is highly anisotropic, with hyperfine coupling constants of 9.1 and 2 × 33.3 G for the [5,6] adduct and ∼0.6 and 2 × 47.9 G for the [6,6] adduct. Remarkably, the subtle variation of the exohedral group position on the surface of the cage results in very pronounced changes of the spin density distribution and on the dynamics of the encapsulated Sc3N cluster.

Fig. 4: Molecular structures, spin density distribution, and ESR spectra of anion radicals of isomeric [5,6] and [6,6] Sc3N@C80 benzoadducts.

[1] A. A. Popov, et al., Chem. Rev. 2013, 113, 5989. [2] Q. Deng and A. A. Popov, J. Am. Chem. Soc. 2014, 136, 4257. [3] Y. Zhang et al., Angew. Chem.-Int. Edit. Engl. 2014, DOI: 10.1002/anie.201409094. [4] A. L. Svitova et al., Nat. Commun. 2014, 5, 3568, DOI: 3510.1038/ncomms4568. [5] (a) Y. Zhang and A. A. Popov, Organometallics 2014, 33, 4537; (b) A. A. Popov and L. Dunsch, J. Phys. Chem. Lett. 2011, 2, 786. [6] Y. Zhang et al., J. Phys. Chem. Lett. 2013, 4, 2404. [7] Y. Zhang et al., Nanoscale 2014, 6, 1038. [8] A. A. Popov et al., J. Am. Chem. Soc. 2014, 136, 13436.

Funding: DFG

Cooperation: Univ. of Texas at El Paso (USA); Univ. of California, Davis (USA); Purdue University at Fort Wayne (USA). Research Area 4 TOWARDS PRODUCTS 67

Research topic 4.1 Surface acoustic waves: Concepts, materials & applications People: S. Biryukov, E. Brachmann, R. Brünig, A. Darinskii2, T. Gemming, V. Hoffmann, F. Kiebert, E. Lattner, G. Martin, S. Menzel, G. K. Rane, H. Schmidt, M. Seifert, E. Smirnova1, A. Sotnikov, M. Spindler, H. Turnow, U. Vogel, A. Vornberger, S. Wege, M. Weihnacht, A. Winkler Responsible Directors: B. Büchner, J. Eckert, O. G. Schmidt

Summary: The center “SAWLab Saxony ” was established bringing together IFW’s competence in acoustoelectronics with those of other Saxon research groups and high-tech companies active in this field. In 2014 the research emphasis was mainly put on the thorough investigation of high temperature durable piezoelectric substrates and appropriate electrode metallization systems for SAW devices as well as on systems with acoustofluidic interaction. Hereby, different new piezoelectric materials were characterized regarding their acoustic behavior and a complete parameter set was established for CTGS crystals as currently the most promising member of langasite family for high temperature applications. As for advanced thin film electrodes systems made of refractor y elements, AlRu alloys and metallic glasses were investigated. Moreover dedicated analysis methods were developed for surface- and interface studies on SAW-based film systems.

In the research topic 4.1 the „SAWLab Saxony - Competence Center for Acoustoelectronic Fundamentals, Technologies and Devices” (www.SAWLab-saxony.de) was founded, joining all microacoustic activities of the IFW Dresden and combining this expertise with competence s and skills of cooperating Saxon research institutes, universities and high- tech companies. This interdisciplinary research includes acoustoelectronic fundamentals and novel materials as well as advanced applications with exploitation by innovation-oriented small and medium-sized enterprises. In this frame, IFW activities will continue to focus on emerging and future-oriented fields of SAW components, like high-grade frequency filters and resonators as well as sensors and actuators with enhanced capabilities. Here, materials aspects are crucial regarding piezoelectric substrates and thin film electrodes with increased temperature and power capabilities necessary for 68 Research Area 4 TOWARDS PRODUCTS

SAW structures with enhanced precision and lifetime. Besides fundamental investigations regarding general effects of wave propagation [1], dynamic behavior of polar dielectrics [2] and acoustofluidic interaction phenomena, the research was also focused on dedicate d materials for high-temperature applications such as i) advanced piezoelectric substrate materials, ii) new routes for thin film electrode materials with high thermal stability and iii) dedicated surface and interface study. i) Advanced piezoelectric substrate materials Besides commercially well-established high frequency filters, resonators and actuators, SAW devices presently capture new fields of application namely as passive SAW-based sensorsand ID tags. Due to inherent robustness and the capability for wireless inter - rogation such devices become ready for an emerging field of industrial and consumer applications. Nevertheless, a remaining challenge is still the required durability against extreme temperatures, particularly in oxidizing atmosphere. Here, new piezoelectric crystals were characterized with high precision regarding their acoustical material parameter s, among them different members of langasite and oxoborate families. A serious alternative for high temperature SAW devices is CTGS (Ca3TaGa3Si2O14) belonging to the same crystal family like the commonly used LGS (langasite, La3Ga5SiO14) but showing a more ordered and thus more stable crystal structure. By combining different techniques based on SAW and BAW (Pulse-Echo, Resonance-Antiresonance, LAwave) with dielectric measurements a strongly improved complete set of acoustic material data was determined for room temperature, overcoming the inaccuracies of formerly known dat a sets. ii) Thin film electrode material systems with high thermal stability High-temperature stable electrode systems based on magnetron sputtered refractory metals like tungsten and molybdenum single and multilayers as well as intermetallic Al(Ru) thin films were investigated on LGS and CTGS substrates. The choice of these material systems is based on their high melting point (> 2000 °C) and thus a minimal creep related damage as well as a compiant coefficient of thermal expansion (CTE) of the materials in contact to the substrates. Additional features are a relatively high thermal conduc - tivity and low electrical resistivity (< 15 μΩcm for 100 nm thin films) which is stable over many temperature cycles. In-depth material characterization was performed to understand and tailor the microstructure using different techniques such as X-ray diffraction and reflectivity measurements, scanning and transmission electron microscopy, Auger electron spectroscopy, atomic force microscopy etc.

Since even at high temperatures a chemical reaction with the substrate was not observed for W/Mo a diffusion barrier to the CTGS substrate is not necessary. A high thermal stabilit y up to 800°C of all the W/Mo films on CTGS was also observed under vacuum (Figs.1,2). The RuAl alloy thin films (thickness 110 nm) have also been heated up to

Fig. 1: Focused ion beam cuts of W/Mo multilayers on CTGS after annealing at 800°C for 12h (a - d: increasing number of layers). Research Area 4 TOWARDS PRODUCTS 69

Fig. 2: Electrical resistivity of different W/Mo thin films on CTGS upon annealing.

800°C. For this materia l system the phase formation, surface morphology, electrical conductivity and film architecture have been investigated. The results show that the RuAl

phase is formed very well on reference Si/SiO2 substrates but oxidation of the Al atoms takes place due to diffusion of O out of LGS and CTGS substrates. This oxidation effect destroys the RuAl phase completely at 800°C on LGS substrates (Fig. 3). This behavior

is less pronounced on CTGS. However, the results on Si/SiO2 reference substrates prove that the RuAl alloy is also a promising metallization candidate for SAW devices, but one needs to overcome the challenges on LGS and CTGS by appropriate barrier layers to inhibit the diffusion of O and to protect the film against oxidation. In conclusion, the W-Mo and Al-Ru materials systems are suitable metallization candidates for high temperature SAW devices, being an alternative to the commercially used Pt thin films electrodes [3].

Thin film metallic glasses are characterized by a high yield strength and a low diffusivity at moderate resistivity compared to crystalline thin films of the same dimensions. Due to the lack of microstructural defects such as grain boundaries (Fig. 4), internal diffusion and degradation effects are drastically reduced. The research has been focused on

Fig. 3: RuAl film composition on LGS after annealing at 800 °C for 10 h under high vacuum condition. Inset: FIB image illustrating film architecture. 70 Research Area 4 TOWARDS PRODUCTS

Fig. 4: FIB cross sections of a crystalline Ni and an amorphous NiZr thin film. fundamental investigations especially on the binary Ni-Zr as well as Cu-Ti material systems for SAW device applications. For this purpose the alloys were deposited by simultaneou s co-sputtering whereas for multilayers the two material components were deposited successively. On both material systems the surface roughness, intrinsic mechanical stress, electrical resistivity, crystal phase formation as well as the Young’s modulus were studied in dependence on composition. It was observed that microstructure and phases have a strong influence on the measured properties. In particular an extremely low surface roughness in the nm range and electrical resistivity below 200 μΩcm are results observed for the amorphous thin films [4].

The interface between the metallization layer and the piezoelectric substrate is crucial regarding the texture of the layers and their microstructure evolution, and thus influences performance and lifetime of SAW devices especially under high acoustic load. Studies on LiNbO3 and LiTaO3 with several metallization layers (Ta, Ti, TaNx, TiNx) emphasize the role of cleaning pre-treatment of the substrate surface on layer performance. Conventional preparation like low energy ion etching or thermal treatment may alter the chemical state of the surface. Based on analytical results using a dedicated Angle-Resolved X-Ray Photoelectron Spectroscopy (ARXPS) algorithm an rf-plasma treatment process was developed that results in an ideal cleaned surface. This ARXPS algorithm allows a complex interface modelling with robust mathematical approach that can lead to further understanding of the interface effects [5].

[1] A.N. Darinskii et al., Ultrasonics, 54, 1999–2005 (2014). [2] E. Smirnova et al., J. Appl. Phys. 15, 054101 (2014). [3] G.K. Rane et al., Thin Solid Films 571 (2014), 1-8. [4] H. Turnow et al., Thin Solid Films, 561C, 48-52 (2014) [5] U. Vogel et al., Surface and Interface Analysis 46 (2014), 1033-1038

Funding: BMBF InnoProfile-Transfer (03IPT610A MiMi, 03IPT610Y HoBelAB), DFG, Vectron International, Creavac, SAW Components Dresden

Cooperations: TU Bergakademie Freiberg; TU Dresden; 1Ioffe Physical Technical Insti- tute RAS, St. Petersburg, Russia; 2Institute for Crystallography RAS, Moscow, Russia; InnoXacs; Vectron International; Creavac, SAW Components Dresden Research Area 4 TOWARDS PRODUCTS 71

Research Topic 4.2 Materials for biomedical applications Authors: A. Gebert, A. Helth, P. Flaviu Gostin, M. Bönisch, K. Zhuravleva, S. Abdi, S. Pilz, R. Schmidt, S. Oswald, H. Wendrock, A. Voß, M. Uhlemann, U. Wolff, D. Pohl, B. Rellinghaus, T. Gemming, M. Calin, U. Hempel1, R. Medda2, E. A. Cavalcanti-Adam2, C. Lekka3 People involved: H. Attar, H. Bußkamp, S. Donath, D. Eigel, M. Frey, M. Guix, S. Hampel, L. Helbig, K. Hennig, V. Hoffmann, J. Hufenbach, M. Johne, S. Kaschube, A. Kippenhahn, T. Kirsten, B. Koch, G. Kreutzer, U. Kühn, V. Magdanz, S. Makharza, M. Medina, A. K. Meyer, S. Pauly, A. Schubert, L. Schwarz, F. Senftleben, A. Teresiak, K. Wruck Responsible Directors: B. Büchner, O. G. Schmidt, J. Eckert

Summary: Advances in biomedical applications require novel material-based solutions under exploitation of their unique properties. The combination of different material classes yields biofunctionalities at greater dimension in analytics, diagnostics and therapeutic s. A profound knowledge-base on the interaction of the material with the biological system has to be developed to tailor materials properties and to control the bio-solid-interface. At the IFW a unique expertise on different material classes for novel biomedical applications is concentrated ranging from nanomaterials (carbon nanostructures, rolled-up materials) over bio-microfluidics and microacoustics based on thin films up to bulk materials. A special research focus are new Ti-based alloys for hard tissue regeneration and replacement with most suitable mechanical performance and excellent biocompatibility. A key aspect is the design of bioactive surface states for optimum bone–metal interactions towards reliable osseointegration also in case of age-induced bone diseases. Successful examples of nanoscale surface modifications of a new generation of Ti-based implant alloys are demonstrated in the following.

Nanoscale surface modification of Ti-based alloys for hard tissue implants A world-wide growing population of elder people and the related rising problem of age- induced bone diseases like osteoporosis tighten the demands on materials properties used for human orthopaedic implants towards better mechanical and biological compat- ibility and longevity. For hard tissue regeneration, Ti and its alloys are the most favoured implant materials, but there are still serious problems to be solved. A major issue is the bone-implant stiffness mismatch causing stress-shielding effects with consequence of bone resorption and implant loosening. Multiple cases of implant failure due to limited materials strength are observed. The release of toxic metallic species by corrosion and 72 Research Area 4 TOWARDS PRODUCTS

wear is problematic due to inflammatory cascades. Suitable surface states must be create d which enable better osseointegration. Therefore, careful material design is necessary to attain optimum biofunctionalities [1]. We develop new non-toxic Ti-based materials with suitable balance of low stiffness and high static and dynamic strength as well as high durability under physiological conditions. This comprises alloy design with particular microstructural features at different length-scales ranging from microcrystalline via nanocrystalline to amorphous states. In the focus are alloys of the metastable Ti-Nb system. For beta-type Ti-(40-45)Nb, compositional modifications with beta stabilizers like indium or grain refiners like boron and variations of casting and thermo-mechanical processing conditions are studied to suitably tailor microstructure-property relations [2]. Porous alloy structures with very low elastic modulus are produced via powder metallurgical approaches and are intend- ed to be used as mechanically stable substrates and carrier of bioresorbable materials or drug delivery systems in bone defects [3]. Special emphasis is given to alloys that mechanically stimulate bone healing processes based on a combination of superelastic and shape memory effects like martensitic Ti-(13-30)Nb [4]. Amorphous Ni- and Cu-free Ti-based alloys are a particular class of materials that are developed towards an optimum balance between maximum glass-forming ability and outstanding mechanical performance and corrosion resistance [5,6]. A decisive prerequisite for long-term implant application of those novel Ti-based alloys is the generation of bioactive surface states for optimum osseointegration. That comprise s the control of the complex processes at the bio-solid interface towards the stimulation of the activity of bone forming cells (osteoclasts) against that of bone re- sorbing cells which is the basis for bone tissue regeneration. The implant surface state with its topography and roughness, composition and surface energy controls these interaction s.Many established surface treatments for commercial Ti-based implant material s yield distinct micrometer-sized features. But recent studies revealed that nanometer-sized modifications better scale with cell functions. Therefore, strategies for the generation of suitable nanoscale surface modifications of the new generation of Ti-based implant materials are to be developed. Selected successful examples for beta- type Ti-Nb alloys are discussed in the following.

The high Nb content of Ti-(40-45)Nb alloys yields an extremely high corrosion resistance and therefore, established acid etching procedures for metallic implant materials are not sufficient for effective surface modification. In a new approach the applicability of a H2SO4 /H2O2 treatment for chemical nanoroughening of the alloy surface was demonstrated [7,8]. The nanotopography comprises a network of nearly semi-spherical pits of 25 nm mean diameter (Fig. 1). While the native passive layer on a mechanically ground alloy surface is very thin and has a mixed state of various Ti and Nb-oxides, the chemical treatment enhances the passive layer growth. A strong enrichment of Nb2O5 relative to TiO2 in the surface layer was detected. The use of analytical methods such as X-ray photoelectro n spectroscopy (XPS) (Fig. 2) and Auger electron spectroscopy (AES) is

Fig. 1: SEM micrograph of a Ti-40Nb surface after chemical nanoroughening Research Area 4 TOWARDS PRODUCTS 73

Fig. 2: XPS spectra of the Ti 2p state taken from a Ti-40Nb surface, polished (black) and nanoroughened (brown); different oxide states are deconvoluted

crucial for the characterization of the materials chemical surface states. But it is challenging due to limited lateral resolution, chemical effects on peak shifts and shapes and the destructive nature of depth-profiling with ion sputtering. Tailored approaches were implemented to allow the calculation of (semi-)quantitative element concentrations from depth profiles [9]. In vitro analyses were conducted at the TU Dresden (AG Hempel) and clearly indicated that chemically nanoroughened Ti-Nb surfaces increase the metaboli c activity and osteogenic differentiation of human mesenchymal stromal cells (hMSC) (Fig. 3). Those effects are significantly more pronounced for the alloy than for cp-Ti.

Fig. 3: Fluorescence micrograph of hMSC on a nanoroughened Ti-40Nb surface (@ U. Hempel, TU Dresden)

When an implant surface is in contact with a physiological environment, one of the first processes is the formation of an extracellular matrix as basis for bone cell adhesion, spreading and differentiation finally leading to bone tissue growth. A recently emerged idea is to stimulate those cell reactions by mimicking an extracellular environment with synthetic means. This comprises the creation of well-defined ordered nano - topographies on bulk solid surfaces in terms of nanoparticle patterns and their functionalization with bioactive molecules. Our collaboration partner at Univ. Heidelberg (AG E.A. Cavalcanti-Adam) developed an approach that starts with nanolithography based on dip 74 Research Area 4 TOWARDS PRODUCTS

coating of Au-loaded diblock copolymer micelles for monolayer formation on a solid substrat e and subsequent oxygen plasma treatment for removal of the organic residues. In our joint study we could demonstrate that by this way highly ordered hexagonal patterns of Au nanoparticles with 5-7 nm diameter and interparticle distances ranging from 70 to 100 nm (depending on the polymer-type used) can be created on fine-polished beta-type Ti-40Nb surfaces. The near-surface regions were characterized with TEM, this way the detailed nature of the fcc Au nanoparticles was analysed and an amorphous passiv e layer of (Ti,Nb)-oxides which was formed during the plasma treatment was detected (Fig. 4). Samples with those surface states were coated with polyethylene glycol and the Au nanoparticles were functionalized with cyclic thiol-peptide ligands. In vitro tests revealed significant effects on the early response of hMSC towards an improved regulation of local cell adhesion and a reduction of the population heterogeneity. Those biofunctionalized nanopatterned alloy surfaces appear to be very promising tools for selecting hMSC with homogeneous phenotype [10].

Fig. 4: TEM image surveying the near-surface regions of Ti-40Nb with passive layer and arrangement of Au nanoparticles

[1] M. Calin et al., Mater. Sci. Eng. C 33 (2013) 875 [2] M. Calin et al., J. Mechan. Beh. Biomed. Mater. 39 (2014) 162 [3] K. Zhuravleva et al., Mater. Design 64 (2014) 1 [4] M. Bönisch et al., J. Appl. Cryst. 47 (2014) 1274 [5] S. Abdi et al., Intermetallics 46 (2014) 156 [6] S. Abdi et al., J. Biomed. Mater Res. Part B (in press) [7] P.F. Gostin et al. J. Biomed. Mater. Res. Part B 101 (2013) 269 [8] A. Helth et al., J. Biomed. Mater. Res. Part B 102 (2014) 31 [9] S. Oswald et al., Surf. Interface Anal. 46 (2014) 683 [10] R. Medda et al., Interface Focus 4 (2014) 20130046

Funding: DFG SFB Transregio 79, EU ( BioTiNet and ITN VitriMetTech), DAAD-IKYDA (Greece)

Cooperations: 1TU Dresden, 2Ruprecht-Karl-Universität Heidelberg, 3Universitity of Ioannina, Greece Research Area 4 TOWARDS PRODUCTS 75

Research topic 4.3 High strength materials Leibniz Application Laboratory Amorphous Metals Authors: U. Kühn, J. Freudenberger, A. Gebert, J. Hufenbach, P.F. Gostin, S. Horn, M. Uhlemann, S. Scudino, A. Leonhardt, F. Silze, J. Sander People involved: B. Bartusch, S. Bickel, R. Buckan, H. Bußkamp, S. Donath, M. Frey, D. Geissler, K. Hennig, M. Johne, R. Keller, E. Knauer, H. Merker, C. Mix, S. Neumann, S. Pauly, K.-G. Prashanth, H. Schwab, D. Seifert, A. Sobolkina, M. Stoica, H. Wendrock, A. Voidel, A. Voß, T. Wolf, J. Zeisig Responsible Directors: J. Eckert, L. Schultz

Summary: The increasing demand of industry for equipment (tools, devices, machine parts, accessories etc.) with excellent durability under extreme loading conditions promotes the development of innovative materials possessing e.g. high strength, hardness, wear resistance, ductility and corrosion resistance. Novel manufacturing technologies, such as special casting methods, which ensure accelerated solidification, selective laser melting and thermoplastic forming present a fast and energy efficient option for load-adapted adjusting of mechanical properties. Materials under investigations are metallic glasses, glass-matrix composites, crystalline materials with extraordinary mechanical properties, as e.g. high strength steels, high strength lightweight alloys, highly strengthened conductors, and cement-based materials reinforced with carbon nanotubes. The basic idea is to transfer sophisticated technologies combined with specific newly developed materials towards industry.

High performance steel alloys This topic contains a multiplicity of activities and projects, respective (1) high strength and/or corrosion resistant tool steels, (2) parts of high strength steels produced by selective laser melting (SLM) and (3) filler material (steel wire) in overlay welding processes. By applying a tailored casting, SLM or welding process and sufficiently high cooling rates excellent mechanical properties (compression strength of up to 5.5 GPa combined with a plastic strain of 20%) can be obtained for the steel alloys already in 76 Research Area 4 TOWARDS PRODUCTS

as-prepare d state [1]. This opened the possibility for reducing multi-stage, time-consuming and cost-intensive manufacturing processes and led to several patents [2-6]. Since no subsequent heat-treatment is required, the cooling parameters applied during the casting process play a key role with respect to the evolving microstructure and resultin g properties. Therefore, detailed investigations of the phase formation, especially the crystal structure and morphology of numerous types of carbides were performed (Fig. 1a, b) [7] and accompanied by thermodynamic modelling work. This resulted in a profound understanding of possible ways for tuning the microstructure and properties of these alloys to certain application purposes, e.g. for cutting/punching/mining tools (Fig. 2a-c) with excellent service life as well as filler material (wire) for deposition welding [6]. Furthermore, reinforcing lattice structures were prepared by SLM for various applications (Fig. 3).

Fig. 1: (a) Optical micrograph of the dendritic

structure of the as-cast Fe84.3Cr4.3Mo4.6V2.2C4.6 alloy Fig. 2: (a) Knives for medical filter production; (b) bucket tooth; showing the distribution of the present phases; (c) pick head for mining machine. (b) SEM image of the deep etched

Fe84.3Cr4.3Mo4.6V2.2C4.6 alloy illustrating the fine High strength metallic materials prepared by SLM network-like structure formed by complex carbides It could be demonstrated for the first time that bulk metallic glasses are producible by and its arrangement within the material. selective laser melting. The method opens a possibility to overcome intrinsic limitations regarding the complexity and dimensions of the obtainable geometries compared to the commonly known casting process. For the first successful experiments an iron-based metallic glass was used, but this approach is viable for a variety of metallic alloys [8]. Furthermore, there is a strong demand from aerospace industry for the development of high strength and lightweight materials with enhanced properties. The SLM process enables the manufacturing of precise and homogenous multicomponent Ti- and Al-based alloys nearly without limits in design and ensures the research on sophisti - cated alloys with very different physical and chemical characteristics [9,10].

Thermoplastic forming of bulk metallic glasses The unique crystallisation behaviour of metallic glasses enables a thermoplastic forming process in the supercooled liquid region (SCLR), because of the significant soften- Fig. 3: Lattice structure produced by SLM technology. ing of the BMGs above Tg. These special characteristics lead to processing temperatures and pressures that are similar to those of plastics. The main advantage is the decoupling of the rapid cooling, required to form the amorphous structure, from the shaping process. In close collaboration with the research technology division of IFW a device has been developed that allows producing semi-finished products of refractory metal-based glassy granulates in protective atmosphere. First parts using such Zr-based glass gran- ulate have been prepared by shaping the glass above the glass transition temperature just in order to demonstrate the feasibility of the technology.

Stress and fatigue corrosion of bulk metallic glasses Stress corrosion cracking investigations are carried out on the bulk glassy

Zr52.5Cu17.9 Al10Ni14.6Ti5 alloy (Vit 105) by means of three-point bending at constant deformation in chloride-containing electrolytes with an in-house designed setup. A specia l three-electrode electrochemical cell is placed around the test sample and enables in situ polarisation control and measurement. Potentiostatic experiments during static mechanical loading are performed at several anodic potentials and chloride Research Area 4 TOWARDS PRODUCTS 77

concentrations selected based on anodic polarisation experiments [11]. Typically, under static loading, after a certain incubation time, the current starts to increase suggesting the initiation of localized corrosion. At a later point, the stress also starts to decrease gradually indicating stress corrosion cracking with stable crack propagation. At the end, unstable crack propagation is observed, which is due to overload of the remaining load-bearing section. Microscopic analysis of fracture surface revealed a clear distinction between the two modes of crack propagation. Stress corrosion cracking is perpendicular to the major tensile stress component. This is accompanied by crack branching and very limited shear banding (Fig. 4).

Fig. 4: SEM image showing the fracture surface of a bulk glassy Zr52.5Cu17.9 Al10 Ni14.6Ti5 alloy (Vit 105) Functionalized carbon nanotubes in cement-based composites sample after a stress corrosion cracking experiment. The use of the reinforcing effect of carbon nanotubes on the tensile strength of cement- based composites requires a strong CNT-matrix interaction which would promote load transfer across the interface. In order to understand and predict the phenomena taking place at the CNT-matrix interface, various types of carbon nanotubes prepared using acetonitrile, cyclohexane, and methane as the carbon source were examined with regard to their surface properties. Working in close collaboration with Leibniz Institute of Polymer Research, significant differences were revealed in the acid-base features, surfac e tension as well as in the wetting behavior of the prepared CNTs. For example, the hydrophobicity of the CNTs decreases by utilizing the carbon sources in the following orde r: cyclohexane, methane, and finally acetonitrile. The sol-gel coating of the CNTs with silica showed strong dependence on the chemical composition of the nanotube surfac e [13]. This basic research is a prerequisite for the specific application of CNTs in inorganic cementitious materials.

High-strength Cu-based conductor materials The microstructure of single phase copper alloys is altered by cold deformation. Depend- ing on the processing parameters like temperature and intrinsic material parameters as stacking fault energy, the dominant deformation mechanism is different and the refinement of the microstructure bears other rates with respect to the deformation strain. The formation of deformation twins is activated at low homologous temperature or at low stacking fault energy. Both also lead to smaller grain sizes achieved at a certain deformatio n strain. Lowering the temperature only yields to a high efficiency in strain hardening with respect to room temperature deformation for intermediate stacking fault energies. The maximum efficiency occurs in the vicinity of the onset of deformation twinnin g at room temperature which was found for a stacking fault energy of 30 mJ/m2. In this condition cryo-deformed CuAl3 alloys show a strength of 890 MPa, which represents an enhancement of 180 MPa when compared to room temperature deformation [14]. Further research will foster this conception of activating mechanical twins by cryo-deformatio n also in CuAg alloys which so far showed the optimum combination of high strength and high electrical conductivity.

Brazing material corresponding to particular industrial requirements Many components used in structural and functional applications are permanently joined by brazing. Therefore, a multitude of different and complex braze fillers are on the market to fulfill the specific requirements defined by each combination of materials. The melting range of the braze filler has to match the target temperature and the process- ability of the alloy has to be adequate in order to ensure large-scale production. In addition, next to a sufficient wettability also the interactions and reactions at the solid- liquid interface are crucial for understanding and improving the brazing process. In cooperation with Umicore AG & Co. KG a substitute alloy for the industrial standard Fig. 5: EDX-Mapping for the wetting of Cu-Ga braze filler on 304L steel in cross section. The dashed line braze filler AgCu28 has been successfully developed and systematically investigated indicates the interface. (Fig. 5). 78 Research Area 4 TOWARDS PRODUCTS

Due to an extensive alloy development combining materials science and industrial demands a composition based on the ternary system Cu-Ag-Ga has been characterized and patented. The new braze filler contains 40% less Ag. The effect of the additional elemen t Ga on the wettability on stainless steel surfaces was investigated on the macro- scopic scale (contact angle measurements) as well as on the microscopic scale (SEM, TEM), so that a detailed understanding of the complex brazing process was achieved.

Electrochemical micromachining of metallic glasses Owing to their outstanding properties bulk metallic glasses are very promising materials for the production of microparts. But shaping them without heat input is still a challenge. An alternative microprocessing method, which operates at room temperature, is the pulsed electrochemical micromachining (ECMM). Employing ultra-short voltage pulses between a micro-sized tool electrode and the BMG surface induces a highly localized material removal process. The applicability was firstly proven for Zr- and Fe-based Fig. 6: Optical micrograph of the surface of a bulk

BMGs using non-aqueous electrolytes. But due to its immanent risks the employment of glassy Fe65.5Cr4Mo4Ga4P12C5B5.5 sample after an methanolic solutions is not favorable. However, using aqueous solutions Fe-based BMGs electrochemical micromachining test in aqueous sulphuric acid solution. form stable passive layers, which disturb the machining. These effects can be minimized by adding an oxidizing agent Fe2(SO4)3 [12]. To demonstrate the high potential of the ECMM optimum hole and line structures were machined (Fig. 6).

[1] J. Hufenbach et al. J. Mater. Sci. 47 (2012) 267 [2] U. Kühn et al. Patent 10608 DE 10 2006 024 358 [3] J. Hufenbach et al. Patent 11017 DE 10 2010 062 011 + 11017 PCT WO2012069329 (pending) [4] U. Kühn et al. Patent 11009 DE 10 2010 041 366.6 + 11009 PCT/EP2011/066283 (pending) [5] J. Zeisig et al. (patent application deposited) [6] J. Hufenbach et al. (patent application deposited) [7] J. Hufenbach et al. Mater. Sci. Eng. A 586 (2013) 267 [8] S. Pauly et al. Mater. Today 16 (2013) 37 [9] K. G. Prashanth et al. Mater. Sci. Eng. A 590 (2014) 163 [10] K. G. Prashanth et al. J. Mater. Res. 29 (2014) 2044 [11] P. F. Gostin et al. J. Mater Res. (accepted) [12] R. Süptitz et al., Electrochimica Acta 109 (2013) [13] A.Sobolkina et al. J. Colloid. Interface Sci. (2014) 413 [14] A. Kauffmann et al. Mater. Sci. Eng A (2015) accepted

Cooperations: Partners within the BMWi funded research LuFo: DLR, EADS, MTU, Rolls-Royce; Partners within the BMWi funded research ZIM: TU Chemnitz, quada V+F; Laserschweißdraht GmbH, LPT – Laserpräzisionstechnik GmbH; SWATCH; BOSCH; WIWeB; DIEHL; UMICORE; The NANOSTEEL company; WIELANDWERKE; TU Dresden, Institute of construction materials; IPF Dresden; University of Kaiserslautern and members SPP 1594 Research Area 4 TOWARDS PRODUCTS 79

Research Topic 4.5 Concepts and materials for superconducting applications People: A. Berger, D. Berger, T. Espenhahn, G. Fuchs, U. Gaitzsch, V. Grinenko, S. Hameister, J. Hänisch, W. Häßler, B. Holzapfel, A. Horst, R. Hühne, A. Kirchner, K. Nenkov, P. Pahlke, E. Reich, T. Seidemann, M. Sieger, M. Sparing, A. Winkler Responsible Director: L. Schultz

Summary: The unique properties of superconducting materials open the way to a wide range of important applications e.g. in the fields of electronics, medicine, research and

energy. Low temperature superconducting materials like NbTi and Nb3Sn are already widely used as high field research magnets and moderate field MRI magnets for medical diagnostics. High temperature superconductors are now on the way to drastically extend the application range towards power systems like motors, cables, fault current limiters as well as ultra-high field magnets and levitation based applications. The centra l aim of this research topic is to investigate superconducting materials and to develo p demonstrator systems that enable the realization of such new applications. This covers the synthesis of high critical current conductors, the controlled pinning enhancement by nano-engineering of superconductors and the realization of demon- stration applications to study new technological directions.

Improved YBCO coated conductors

The main focus of our work in the last year was on the preparation of thick YBa2Cu3O7-x layers with artificial pinning centers on metallic substrates. Therefore, we used highly textured Ni-W templates with a W content of up to 9.5 at.% prepared by the rolling bi- axially textured substrates (RABiTS) approach as well as ion-beam textured YSZ layers on stainless steel. The superconducting layers were grown with pulsed laser deposition

in a high growth rate scheme. The main emphasis was on the incorporation of BaHfO3 nanoparticles with different volume content (Fig.1). It was shown that a significant 80 Research Area 4 TOWARDS PRODUCTS

improvement of the critical current density in magnetic fields Jc(B) was achieved using this approach [1]. Alternatively, BaYNbTaO6 nanoparticles were embedded in films on

SrTiO3 single crystals. The formation of defined nanorods was observed leading to a significant increase of the pinning for fields parallel to the c-axis.

MgB2 – Wires and permanent bulk magnets An internal Magnesium diffusion described recently in literature was applied as a new technology for the preparation of MgB2-wires. This approach is based on diffusion of metallic Magnesium in the surrounding Boron powder during heat treatment and gives denser filaments in comparison to the classic in-situ technique as basis for higher 2 critica l current densities. An engineering critical current density Je of 10 kA/cm at 4.2 K and 5 T was achieved for mono-core wires. These parameters were recently transferred to a seven filament wire.

Last year we reported on high trapped field values of 3.2 T at 15K measured in MgB2 bulk samples of 1.5mm thickness (Fig. 2). In a study on the thickness dependence of trapped fields we found that at high temperatures (T∼ 24K) the optimum sample thickness is ∼ 1mm as for thicker samples only its outer part of ∼ 1mm thickness contributes to the trapped field due to the strong field dependence of the critical current density. At low- ∼ er temperatures (T 15K), an insufficient thermal stability prevents a simple thickness Fig. 1: TEM images of 2 mol% BHO:YBCO on Ni9W: scalability of the trapped field which is limited by flux jumps. To overcome this problem, (a) coated conductor architecture; (b) c-axis oriented pairs of about 2 mm thick samples separated by a spacer will be used at 15K in order to nanorods of BaHfO3 (white arrows mark BHO increase the trapped field available in a relative large volume between the two samples. nanoparticles).

Superconducting motors and AC losses in YBCO coils Pancake coils made from YBCO coated conductors have high critical currents and are attractiv e for application in superconducting motors. However, the AC losses of YBCO windings are at present too high, especially if the additional effort for the cooling equipmen t is taken into account. The main contribution to the AC loss of YBCO coils is 3 the hysteretic loss in the superconductor, Physt ∝ Br , which is basically determined by the large radial component Br of the AC self-field in the coil. In superconducting trans- verse flux motors, a ring shaped double-pancake YBCO coil is used which is enclosed by a soft magnetic yoke with a claw-pole structure. The magnetic flux travelling in trans- verse direction (perpendicular to the direction of rotation) acts as flux diverter and slightly reduces the radial field in the YBCO coil. We have shown by FEM simulations that this effect can be strongly enhanced by including two ferromagnetic foils close to the plane face sides of the YBCO coil. From the simulations, a strong reduction of the radial Fig. 2: Hot pressed MgB2 bulk sample used as field Br by a factor of three is expected which would reduce the AC loss of the specific superconducting permanent magnet. motor considered here on values Physt ≤ 20 W.

Superconducting magnetic bearings in rotating high-speed textile machines Our research activities on small scale levitation applications properties are embedded in the framework of a joint 3-year DFG project with the Institute of Textile Machinery and High Performance Material Technology at the TU Dresden. The work is focused on the implementation and characterization of rotation ring-shaped superconducting magnetic bearings (SMBs) in high-speed textile processing machines for the mass production of short staple yarn. The majority of the short staple yarn produced worldwide today is spun with the traditional ring spinning technique. The productivity of this process depends on the rotational speed of the spindle. It is limited by friction in the so-called ring- travele r twist element (Fig. 3a). During the spinning process the traveler is dragged along the ring-rail by the yarn with up to 30000 rpm. The resulting friction causes wear of the twist element and melting of synthetic yarns at high spindle speeds due to strong heat generation. Research Area 4 TOWARDS PRODUCTS 81

Fig. 3: (a) Conventional ring-traveler twist The replacement of the ring-traveler twist element by a superconducting magnetic element in ring spinning. The small c-shaped bearing was proposed to overcome this friction induced productivity limit [2]. SMBs are traveler is dragged along the immobile ring by inherently passive and contact-less bearings consisting, in this case, of a permanent- the yarn. (b) Superconducting magnetic bearing as twist element. The magnetic ring is rotated magnetic NdFeB ring acting as yarn driven traveler and a stationary superconducting by the yarn winding onto the spindle. YBa2Cu3O7-x ring cooled on 77 K in a cryostat (Fig. 3b). With a first prototype of our SMB twist element in an open bath cryostat, several hundred meters of yarn were spun and the yarn quality was found to be comparable to conventional ring spun yarn [3]. There- fore, a ring-shaped flow-through cryostat was developed and built in cooperation with our industrial partner evico GmbH. Superconducting rings were assembled from prese- lected bulks, prepared at the IFW by a melt texturing technique. Simultaneously we starte d to investigate experimentally as well as describe theoretically the static and dynamic behavior of the SMB, e.g. forces, displacements and precession, with respect to the ring spinning process [4].

Large Scale Application: SupraTrans II After the completion, the test drive facility SupraTrans II is used now for scientific investigation. Particular emphasis lies on the study of the behavior under practical op- Fig. 4: Model of an electromagnetic track using eration conditions and the development of new components such as electromagnetic superconducting tapes: (a) Field calculation by tracks and fast switchable electromagnetic turnouts. First result of a PhD work on such FEM (Comsol); (b) Parts of the experimental model; (c) schematic view of the assembled new system components is a model of an electromagnetic track using superconducting experimental model. tapes to create the magnetomotive force needed (Fig. 4). Simultaneously, the test 82 Research Area 4 TOWARDS PRODUCTS

drive facility is used for a general dissemination of superconductivity to the wider public (pupils, students, vocational training etc.) as well as for professional presentations to contact potential users of this new technology. Furthermore, a PROBRAL-Project together with the Alberto Luiz Coimbra Institute for Graduate Studies and Research in Engineering (COPPE) at the Federal University of Rio de Janeiro was started in 2014. This institute opened its own straight outdoor super- conductive levitation line, the MagLev Cobra. The aim of the exchange project is to examine and compare the driveway characteristics of the the SupraTrans and the MagLev Cobra, which are different in design, as well as to study the behavior of such systems for an outdoor application and on curved tracks.

[1] M. Sieger et al., IEEE Trans. Appl. Supercond. 25 (2015) DOI: 10.1109/TASC.2014.2372903 [2] C. Cherif et al. “Patent WO 2012/100964 A2, International, (2012) [3] M. Hossain et al., Text. Res. J., 84 (2014) 871 [4] M. Sparing et al., IEEE Trans. Appl. Supercond. 25 (2015) DOI: 10.1109/TASC.2014.2366001

Funding: EU (EuroTapes), DFG, BMBF (Project Diamant), DAAD PPP PROBRAL

Cooperations: Bruker HTS, Alzenau, Germany; THEVA GmbH, Ismaning, Germany; University of Cambridge, United Kingdom; ICMAB Barcelona, Spain; University of Vienna, Austria; COPPE/UFRJ, Rio de Janeiro, Brazil; evico GmbH, Dresden, Germany; Institute of Textile Machinery and High Performance Material Technology at the TU Dresden; Festo AG & Co KG, Esslingen, Germany; KIT, Karlsruhe, Germany; Siemens CT Erlangen, Germany; IEE Bratislava (SAS), Slovakia Publications 2014 83

Publications 2014

Monographs and Editorships 1) Physics of quantum rings, V. Fomin (ed.); Berlin: Springer-Verl., Series: NanoScience and Technology, 2014, 310 S. 2) W. Kuch, R. Schaefer, P. Fischer, U. Hillebrecht, Magnetic microscopy of layered structures, Springer-Verl., 2014, 246 S. 3) J. Thomas, T. Gemming, Analytical transmission electron microscopy - An introduction for operators, Springer-Verl., 2014, 382 S.

Journal Papers 1) M. Abdel-Hafiez, P.J. Pereira, S.A. Kuzmichev, T.E. Kuzmicheva, V.M. Pudalov, L. Harnagea, A.A. Kordyuk, A.V. Silhanek, V.V. Moshchalkov, B. Shen, H.-H. Wen, A.N. Vasiliev, X.-J. Chen, Lower critical field and SNS- Andreev spectroscopy of 122-arsenides: Evidence of nodeless superconducting gap, Physical Review B 90 (2014) Nr. 5, S. 54524/1-9. 2) S. Abdi, M. Samadi Khoshkhoo, O. Shuleshova, M. Boenisch, M. Calin, L. Schultz, J. Eckert, M.D. Baro, J. Sort, A. Gebert, Effect of Nb addition on microstructure evolution and nanomechanical properties of a glass-forming Ti-Zr-Si alloy, Intermetallics 46 (2014), S. 156-163. 3) J. Akola, P. Jovari, I. Kaban, I. Voleska, J. Kolar, T. Wagner, R.O. Jones, Structure, electronic, and vibrational properties of amorphous AsS2 and AgAsS2: Experimentally constrained density functional study, Physical Review B 89 (2014) Nr. 6, S. 64202/1-9. 4) F. Ali, S. Scudino, M.S. Anwar, R.N. Shahid, V.C. Srivastava, V. Uhlenwinkel, M. Stoica, G. Vaughan, J. Eckert, Al-based metal matrix composites reinforced with Al-Cu-Fe quasicrystalline particles: Strengthening by interfacial reaction, Journal of Alloys and Compounds 607 (2014), S. 274-279. 5) G. Allodi, R. De Renzi, K. Zheng, S. Sanna, A. Sidorenko, C. Baumann, L. Righi, F. Orlandi, G. Calestani, Band filling effect on polaron localization in La1-x(CaySr1-y)xMnO3 manganites, Journal of Physics: Condensed Matter 26 (2014), S. 266004/1-16. 6) B. Anis, F. Boerrnert, M.H. Ruemmeli, C.A. Kuntscher, Optical microspectroscopy study of the mechanical stability of empty and filled carbon nanotubes under hydrostatic pressure, The Journal of Physical Chemistry C 118 (2014), S. 27048-27062. 7) H. Attar, M. Boenisch, M. Calin, L.-C. Zhang, S. Scudino, J. Eckert, Selective laser melting of in situ titanium-titanium boride composites: Processing, microstructure and mechanical properties, Acta Materialia 76 (2014), S. 13-22. 8) H. Attar, M. Boenisch, M. Calin, L.C. Zhang, K. Zhuravleva, A. Funk, S. Scudino, C. Yang, J. Eckert, Comparative study of microstructures and mechanical properties of in situ Ti-TiB composites produced by selective laser melting, powder metallurgy, and casting technologies, Journal of Materials Research 29 (2014), S. 1941-1950. 9) H. Attar, M. Calin, L.C. Zhang, S. Scudino, J. Eckert, Manufacture by selective laser melting and mechanical behavior of commercially pure titanium, Materials Science and Engineering A 593 (2014), S. 170-177. 10) A. Bachmatiuk, R.F. Abelin, H.T. Quang, B. Trzebicka, J. Eckert, M.H. Ruemmeli, Chemical vapor deposition of twisted bilayer and few-layer MoSe2 over SiO x substrates, Nanotechnology 25 (2014) Nr. 36, S. 365603/1-5. 11) A. Bachmatiuk, A. Dianat, F. Ortmann, H.T. Quang, M.O. Cichocka, I. Gonzalez-Martinez, L. Fu, B. Rellinghaus, J. Eckert, G. Cuniberti, M.H. Ruemmeli, Graphene coatings for the mitigation of electron stimulated desorption and fullerene cap formation, Chemistry of Materials 26 (2014), S. 4998-5003. 12) S.-H. Baek, R. Klingeler, C. Neef, C. Koo, B. Buechner, H.-J. Grafe, Unusual spin fluctuations and magnetic frustration in olivine and non-olivine LiCoPO4 detected by 31P and 7Li nuclear magnetic resonance, Physical Review B 89 (2014) Nr. 13, S. 134424/1-6. 13) S.-H. Baek, L.M. Reinold, M. Graczyk-Zajacb, R. Riedel, F. Hammerath, B. Buechner, H.-J. Grafe, Lithium dynamics in carbon-rich polymer-derived SiCN ceramics probed by nuclear magnetic resonance, Journal of Power Sources 253 (2014), S. 342-348. 14) S. Bahr, A. Alfonsov, G. Jackeli, G. Khaliullin, A. Matsumoto, T. Takayama, H. Takagi, B. Buechner, V. Kataev, Low-energy magnetic excitations in the spin-orbital Mott insulator Sr2IrO4, Physical Review B 89 (2014) Nr. 18, S. 180401(R)/1-4. 15) N. Balchev, E. Nazarova, K. Buchkov, K. Nenkov, J. Pirov, B. Kunev, Effect of Sn-doping on the superconducting properties of HoBa2Cu3Oy, obtained by the MTG method, Journal of Superconductivity and Novel Magnetism 27 (2014) Nr. 3, S. 763-769. 16) C. Balz, B. Lake, H. Luetkens, C. Baines, T. Guidi, M. Abdel-Hafiez, A.U.B. Wolter, B. Buechner, I.V. Morozov, E.B. Deeva, O.S. Volkova, A.N. Vasiliev, Quantum spin chain as a potential realization of the Nersesyan-Tsvelik model, Physical Review B 90 (2014) Nr. 6, S. 60409(R)/1-5. 17) S. Bance, H. Oezelt, T. Schrefl, G. Ciuta, N.M. Dempsey, D. Givord, M. Winklhofer, G. Hrkac, G. Zimanyi, O. Gutfleisch, T.G. Woodcock, T. Shoji, M. Yano, A. Kato, A. Manabe, Influence of defect thickness on the angular dependence of coercivity in rare-earth permanent magnets, Applied Physics Letters 104 (2014), S. 182408/1-5. 18) K. Baroudi, C. Yim, H. Wu, Q. Huang, J.H. Roudebush, E. Vavilova, H.-J. Grafe, V. Kataev, B. Buechner, H. Ji, C. Kuo, C., Z. Hu, T.-W. Pi, C. Pao, J. Lee, D. Mikhailova, L.H. Tjeng, R.J. Cava, Structure and propertie sof alpha—NaFeO2-type ternary sodium iridates, Journal of Solid State Chemistry 210 (2014), S. 195-205. 19) K. Barros, J.W.F. Venderbos, G.-W. Chern, C.D. Batista, Exotic magnetic orderings in the kagome Kondo-lattice model, Physical Review B 90 (2014), S. 245119/1-13. 20) M. Bartusch, M. Hetti, D. Pospiech, M. Riedel, J. Meyer, C. Toher, V. Neu, I. Gazuz, L.S. Shagolsem, J.-U. Sommer, R.-D. Hund, C. Cherif, F. Moresco, G. Cuniberti, B. Voit, Innovative molecular design for a volume oriented component diagnostic: Modified magnetic nanoparticles on high performance yarns for smart textiles, Advanced Engineering Materials 16 (2014) Nr. 10, S. 1276-1283. 21) A. Bauer, A. Regnat, C.G.F. Blum, S. Gottlieb-Schoenmeyer, B. Pedersen, M. Meven, S. Wurmehl, J. Kunes, C. Pfleiderer, Low-temperature properties of single-crystal CrB2, Physical Review B 90 (2014) Nr. 6, S. 64414/1-14. 22) J. Bielecki, A.D. Rata, L. Boerjesson, Femtosecond optical reflectivity measurements of lattice-mediated spin repulsions in photoexcited LaCoO3 thin films, Physical Review B 89 (2014) Nr. 3, S. 35129/1-5. 84 Publications 2014

23) T. Biemelt, C. Selzer, F. Schmidt, G. Mondin, A. Seifert, K. Pinkert, S. Spange, T. Gemming, S. Kaskel, Hierarchical porous zeolite ZSM-58 derived by desilication and desilication re-assembly, Microporous and Mesoporous Materials 187 (2014), S. 114-124. 24) V. Bilovol, L.G. Pampillo, D. Meier, U. Wolff, F. Saccone, Cobalt ferrite films: Nanopolishing and magnetic properties, IEEE Transactions on Magnetics 50 (2014) Nr. 9, S. 6000305/1-5. 25) V. Bisogni, S. Kourtis, C. Monney, K. Zhou, R. Kraus, C. Sekar, V. Strocov, B. Buechner, J. van den Brink, L. Braicovich, T. Schmitt, M. Daghofer, J. Geck, Femtosecond dynamics of momentum-dependent magnetic excitations from resonant inelastic X-Ray scattering in CaCu2O3, Physical Review Letters 112 (2014), S. 147401/1-5. 26) F. Bittner, S. Yin, A. Kauffmann, J. Freudenberger, H. Klauss, G. Korpala, R. Kawalla, W. Schillinger, L. Schultz, Dynamic recrystallisation and precipitation behaviour of high strength and highly conducting Cu-Ag-Zr-alloys, Materials Science and Engineering A 597 (2014), S. 139-147. 27) B. Boehme, C.B. Minella, F. Thoss, I. Lindemann, M. Rosenburg, C. Pistidda, C.T. Moeller, T.R. Jensen, L. Giebeler, M. Baitinger, O. Gutfleisch, H. Ehrenberg, J. Eckert, Y. Grin, L. Schultz, B1 - Mobilstor: Materials for sustainable energy storage techniques - Lithium containing compounds for hydrogen and electrochemical energy storage, Advanced Engineering Materials 16 (2014) Nr. 10, S. 1183-1195. 28) M. Boenisch, M. Calin, L. Giebeler, A. Helth, A. Gebert, W. Skrotzki, J. Eckert, Composition-dependent magnitude of atomic shuffles in Ti-Nb martensites, Journal of Applied Crystallography 47 (2014), S. 1374-1379. 29) F. Boerrnert, T. Riedel, H. Mueller, M. Linck, B. Buechner, H. Lichte, A dedicated In-situ off-axis electron holography (S)TEM: Concept and electron-optical performance, Microscopy and Microanalysis 20 (2014) Nr. Suppl. 3, S. 1650-1651. 30) F. Boerrnert, R. Voigtlaender, B. Rellinghaus, B. Buechner, M.H. Ruemmeli, H. Lichte, A cheap and quickly adaptable in situ electrical contacting TEM sample holder design, Ultramicroscopy 139 (2014), S. 1-4. 31) S. Boettner, S. Li, M.R. Jorgensen, O.G. Schmidt, Polarization resolved spatial near-field mapping of optical modes in an on-chip rolled-up bottle microcavity, Applied Physics Letters 105 (2014), S. 121106/1-5. 32) C.C. Bof Bufon, C. Vervacke, D.J. Thurmer, M. Fronk, G. Salvan, S. Lindner, M. Knupfer, D.R.T. Zahn, O.G. Schmidt, Determination of the charge transport mechanisms in ultrathin copper phthalocyanine vertical heterojunctions, The Journal of Physical Chemistry C 118 (2014), S. 7272-7279. 33) A. Bogusz, A.D. Mueller, D. Blaschke, I. Skorupa, D. Buerger, A. Scholz, O.G. Schmidt, H. Schmidt, Resistive switching in polycrystalline YMnO3 thin films, AIP Advances 4 (2014), S. 107135/1-8. 34) A. Bonatto Minella, D. Pohl, C. Taeschner, R. Erni, R. Ummethala, M.H. Ruemmeli, L. Schultz, B. Rellinghaus, Silicon carbide embedded in carbon nanofibres: Structure and band gap determination, Physical Chemistry, Chemical Physics: PCCP 16 (2014), S. 24437-24442. 35) C. Bonavolonta, C. de Lisio, M. Valentino, L. Parlato, G.P. Pepe, F. Kurth, K. Iida, Evaluation of superconducting gaps in optimally doped Ba(Fe1xCox)2As2/Fe bilayers by ultrafast time-resolved spectroscopy, Physica C 503 (2014), S. 132-135. 36) L. Borchardt, M. Oschatz, S. Graetz, M.R. Lohe, M.H. Ruemmeli, S. Kaskel, A hard-templating route towards ordered mesoporous tungsten carbide and carbide-derived carbons, Microporous and Mesoporous Materials 186 (2014), S. 163-167. 37) S. Borisenko, Q. Gibson, D. Evtushinsky, V. Zabolotnyy, B. Buechner, R.J. Cava, Experimental realization of a three-dimensional dirac semimetal, Physical Review Letters 113 (2014) Nr. 2, S. 27603/1-. 38) V. Brackmann, V. Hoffmann, A. Kauffmann, A. Helth, J. Thomas, H. Wendrock, J. Freudenberger, T. Gemming, J. Eckert, Glow discharge plasma as a surface preparation tool for microstructure investigations, Materials Characterization 91 (2014), S. 76-88. 39) J. Brand, A. Stunault, S. Wurmehl, L. Harnagea, B. Buechner, M. Meven, M. Braden, Spin susceptibility in superconducting LiFeAs studied by polarized neutron diffraction, Physical Review B 89 (2014) Nr. 4, S. 45141/1-5. 40) M. Brehm, M. Grydlik, F. Schaeffler, O.G. Schmidt, Evolution and coarsening of Si-rich SiGe islands epitaxially grown at high temperatures on Si(001), Microelectronic Engineering 125 (2014), S. 22-27. 41) N. Brun, K. Sakaushi, J. Eckert, M.M. Titirici, Carbohydrate-derived nanoarchitectures: On a synergistic effect toward an improved performance in Lithium-Sulfur batteries, ACS Sustainable Chemistry and Engineering 2 (2014), S. 126-129. 42) W. Brzezicki, M. Daghofer, A.M. Ole, Mechanism of hole propagation in the orbital compass models, Physical Review B 89 (2014) Nr. 2, S. 24417/1-11. 43) M. Calin, A. Helth, J.J. Gutierrez Moreno, M. Boenisch, V. Brackmann, L. Giebeler, T. Gemming, C.E. Lekka, A. Gebert, R. Schnettler, J. Eckert, Elastic softening of Beta-type Ti-Nb alloys by indium (In) additions, Journal of the Mechanical Behavior of Biomedical Materials 39 (2014), S. 162-174. 44) R.D. Cava, C. Bolfarini, C.S. Kiminami, E.M. Mazzer, W.J. Botta Filho, P. Gargarella, J. Eckert, Spray forming of Cu-11.85Al-3.2Ni-3Mn (wt%) shape memory alloy, Journal of Alloys and Compounds 615 (2014) Nr. S1, S. S602-S606. 45) P. Cendula, A. Malachias, C. Deneke, S. Kiravittaya, O.G. Schmidt, Experimental realization of coexisting states of rolled-up and wrinkled nanomembranes by strain and etching control, Nanoscale 6 (2014), S. 14326-14335. 46) A. Charnukha, Optical conductivity of iron-based superconductors, Journal of Physics: Condensed Matter 26 (2014) Nr. 25, S. 253203/1-35. 47) A.K. Chaubey, S. Scudino, M. Samadi Khoshkhoo, K.G. Prashanth, N.K. Mukhopadhyay, B.K. Mishra, J. Eckert, High-strength ultrafine grain Mg- 7.4% Al alloy synthesized by consolidation of mechanically alloyed powders, Journal of Alloys and Compounds 610 (2014), S. 456-461. 48) P. Chen, J.J. Zhang, J.P. Feser, F. Pezzoli, O. Moutanabbir, S. Cecchi, G. Isella, T. Gemming, S. Baunack, G. Chen, O.G. Schmidt, A. Rastelli, Thermal transport through short-period SiGe nanodot superlattices, Journal of Applied Physics 115 (2014) Nr. 4, S. 44312/1-10. Publications 2014 85

49) A. Chikina, M. Hoeppner, S. Seiro, K. Kummer, S. Danzenbaecher, S. Patil, A. Generalov, M. Guettler, Y. Kucherenko, E.V. Chulkov, Y.M. Koroteev, K. Koepernik, C. Geibel, M. Shi, M. Radovic, C. Laubschat, D.V. Vyalikh, Strong ferromagnetism at the surface of an antiferromagnet caused by buried magnetic moments, nature communications 5 (2014), S. 4171/1-. 50) A.V. Chubukov, J.J. Betouras, D.V. Efremov, Non-Landau damping of magnetic excitations in systems with localized and itinerant electrons, Physical Review Letters 112 (2014) Nr. 3, S. 37202/1-5. 51) M.O. Cichocka, J. Zhao, A. Bachmatiuk, H.T. Quang, S.M. Gorantla, I.G. Gonzalez-Martinez, L. Fu, J. Eckert, J.H. Warner, M.H. Ruemmeli, In situ observations of Pt nanoparticles coalescing inside carbon nanotubes, RSC Advances 4 (2014), S. 49442-49445. 52) D. Comtesse, M.E. Gruner, M. Ogura, V.V. Sokolovskiy, V.D. Buchelnikov, A. Gruenebohm, R. Arroyave, N. Singh, T. Gottschall, O. Gutfleisch, V.A. Chernenko, F. Albertini, S. Faehler, P. Entel, First-principles calculation of the instability leading to giant inverse magnetocaloric effects, Physical Review B 89 (2014) Nr. 18, S. 184403/1-6. 53) M. Daghofer, M. Hohenadler, Phases of correlated spinless fermions on the honeycomb lattice, Physical Review B 89 (2014) Nr. 3, S. 35103/1-3. 54) A.N. Darinskii, M. Weihnacht, H. Schmidt, Rayleigh wave scattering from a vertical edge of isotropic substrates, Ultrasonics 54 (2014), S. 1999-2005. 55) S. Das, A. Herklotz, E.J. Guo, K. Doerr, Static and reversible elastic strain effects on magnetic order of La0.7Ca0.3MnO3/SrTiO3 superlattices, Journal of Applied Physics 115 (2014) Nr. 14, S. 143902/1-5. 56) K. Davami, M. Shaygan, N. Kheirabi, J. Zhao, D.A. Kovalenko, M.H. Ruemmeli, J. Opitz, G. Cuniberti, J.-S. Lee, M. Meyyappan, Synthesis and characterization of carbon nanowalls on different substrates by radio frequency plasma enhanced chemical vapor deposition, Carbon 72 (2014), S. 372-380. 57) M. de Pauli, M.J.S. Matos, P.F. Siles, M.C. Prado, B.R.A. Neves, S.O. Ferreira, M.S.C. Mazzoni, A. Malachias, Chemical stabilization and improved thermal resilience of molecular arrangements: Possible formation of a surface network of bonds by Multiple Pulse Atomic Layer Deposition, The Journal of Physical Chemistry B 118 (2014), S. 9792-9799. 58) L. Ding, S. He, S. Miao, M.R. Jorgensen, S. Leubner, C. Yan, S.G. Hickey, A. Eychmueller, J. Xu, O.G. Schmidt, Ultrasmall SnO2 nanocrystals: Hot-bubbling synthesis, encapsulation in Carbon layers and applications in high capacity Li-Ion storage, Scientific Reports 4 (2014), S. 4647/1-8. 59) I. Dirba, S. Sawatzki, O. Gutfleisch, Net-shape and crack-free production of Nd-Fe-B magnets by hot deformation, Journal of Alloys and Compounds 589 (2014), S. 301-306. 60) G. Doerfel, Der Meister und seine Schule - Zur Biographie und Wirkung des Instrumentenbauers Heinrich Geissler, Sudhoffs Archiv - Zeitschrift fuer Wissenschaftsgeschichte 98 (2014) Nr. 1, S. 91-108. 61) S. Doerfler, K. Pinkert, M. Weiser, C. Wabnitz, A. Goldberg, B. Ferse, L. Giebeler, H. Althues, M. Schneider, J. Eckert, A. Michaelis, E. Beyer, S. Kaskel, D2 Enertrode: Production technologies and component integration of nanostructured carbon electrodes for energy technology - Functionalized carbon materials for efficient electrical energy supply, Advanced Engineering Materials 16 (2014) Nr. 10, S. 1196-1201. 62) S. Doering, M. Monecke, S. Schmidt, F. Schmidl, V. Tympel, J. Engelmann, F. Kurth, K. Iida, S. Haindl, I. Moench, B. Holzapfel, P. Seidel, Investigation of TiO x barriers for their use in hybrid Josephson and tunneling junctions based on pnictide thin films, Journal of Applied Physics 115 (2014), S. 83901/1-5. 63) P. Donnadieu, C. Pohlmann, S. Scudino, J.-J. Blandin, K.B. Surreddi, J. Eckert, Deformation at ambient and high temperature of in situ Laves phases-ferrite composites, Science and Technology of Advanced Materials 15 (2014), S. 34801/1-8. 64) J. Dreiser, R. Westerstroem, C. Piamonteze, F. Nolting, S. Rusponi, H. Brune, S. Yang, A. Popov, L. Dunsch, T. Greber, X-ray induced demagnetization of single-molecule magnets, Applied Physics Letters 105 (2014) Nr. 3, S. 32411/1-5. 65) J. Dreiser, R. Westerstroem, Y. Zhang, A.A. Popov, L. Dunsch, K. Kraemer, S.-X. Liu, S. Decurtins, T. Greber, The metallofullerene field-induced single-ion magnet HoSc2N-at- C80, Chemistry - A European Journal 20 (2014) Nr. 42, S. 13536-13540. 66) N. Du, N. Manjunath, Y. Shuai, D. Buerger, I. Skorupa, R. Schueffny, C. Mayr, D.N. Basov, M. Di Ventra, O.G. Schmidt, H. Schmidt, Novel implementation of memristive systems for data encryption and obfuscation, Journal of Applied Physics 115 (2014) Nr. 12, S. 124501/1-7. 67) M. Emmel, A. Alfonsov, D. Legut, A. Kehlberger, E. Vilanova, I.P. Krug, D.M. Gottlob, M. Belesi, B. Buechner, M. Klaeui, P.M. Oppeneer, S. Wurmehl, H.J. Elmers, G. Jakob, Electronic properties of Co2FeSi investigated by X-raymagnetic linear dichroism, Journal of Magnetism and Magnetic Materials 368 (2014), S. 364-373. 68) P. Entel, M.E. Gruner, D. Comtesse, V.V. Sokolovskiy, V.D. Buchelnikov, Interacting magnetic cluster-spin glasses and strain glasses in Ni–Mn based Heusler structured intermetallics, Physica Status Solidi B 251 (2014) Nr. 10, S. 2135-2148. 69) D. Ernst, M. Melzer, D. Makarov, F. Bahr, W. Hofmann, O.G. Schmidt, T. Zerna, Packaging technologies for (Ultra-)thin sensor applications in active magnetic bearings, 37th International Spring Seminar on Electronics Technology (ISSE), in: Proceedings, 125-129 (2014). 70) A. Eschke, J. Scharnweber, C.-G. Oertel, W. Skrotzki, T. Marr, J. Romberg, J. Freudenberger, L. Schultz, I. Okulov, U. Kuehn, J. Eckert, Texture development in Ti/Al filament wires produced by accumulative swaging and bundling, Materials Science and Engineering A 607 (2014), S. 360-367. 71) A. Eschke, W. Zinn, T. Marr, C.-G. Oertel, W. Skrotzki, L. Schultz, J. Eckert, Local stress gradients in Ti/Al composite wires determined by two-dimensional X-ray microdiffraction, Materials Science and Engineering A 616 (2014), S. 44-54. 72) D.V. Evtushinsky, V.B. Zabolotnyy, T.K. Kim, A.A. Kordyuk, A.N. Yaresko, J. Maletz, S. Aswartham, S. Wurmehl, A.V. Boris, D.L. Sun, C.T. Lin, B. Shen, H.H. Wen, A. Varykhalov, R. Follath, B. Buechner, S.V. Borisenko, Strong electron pairing at the iron 3dxz, yz orbitals in hole-doped BaFe2As2 superconductors revealed by angle-resolved photoemission spectroscopy, Physical Review B 89 (2014) Nr. 6, S. 64514/1-12. 86 Publications 2014

73) A.V. Fedorov, N.I. Verbitskiy, D. Haberer, C. Struzzi, L. Petaccia, D. Usachov, O.Y. Vilkov, D.V. Vyalikh, J. Fink, M. Knupfer, B. Buechner, A. Grueneis, Observation of a universal donor-dependent vibrational mode in graphene, nature communications 5 (2014), S. 3257/1-8. 74) P. Feng, G. Wu, O.G. Schmidt, Y. Mei, Photosensitive hole transport in Schottky-contacted Si nanomembranes, Applied Physics Letters 105 (2014) Nr. 12, S. 121101/1-5. 75) P.P. Ferguson, D.-B. Leb, A.D.W. Todd, M.L. Martine, S. Trussler, M.N. Obrovac, J.R. Dahn, Nanostructured Sn30Co30C40 alloys for lithium-ion battery negative electrodes prepared by horizontal roller milling, Journal of Alloys and Compounds 595 (2014), S. 138-141. 76) P.P. Ferguson, A.D.W. Todd, M.L. Martine, J.R. Dahn, Structure and performance of Tin-Cobalt-Carbon alloys prepared by attriting, roller milling and sputtering, Journal of The Electrochemical Society 161 (2014), S. A342-A347. 77) V.V. Fisun, O.P. Balkashin1, O.E. Kvitnitskaya, I.A. Korovkin, N.V. Gamayunova, S. Aswartham, S. Wurmehl, Y.G. Naidyuk, Josephson effect and Andreev reflection in Ba1 -xNaxFe2As2 (x50.25 and 0.35) point contacts, Low Temperature Physics 40 (2014) Nr. 10, S. 919-924. 78) V.M. Fomin, M. Hippler, V. Magdanz, L. Soler, S. Sanchez, O.G. Schmidt, Propulsion mechanism of catalytic microjet engines, IEEE Transactions on Robotics 30 (2014) Nr. 1, S. 40-48. 79) Y. Fuji, S. Nishimoto, H. Nakada, M. Oshikawa, Quantum criticality in an asymmetric three-leg spin tube: A strong rung-coupling perspective, Physical Review B 89 (2014) Nr. 5, S. 54425/1-13. 80) I. Galkina, A. Tufatullin, D. Krivolapov, Y. Bakhtiyarova, D. Chubukaeva, V. Stakheev, V. Galkin, R. Cherkasov, B. Buechner, O. Kataeva, Crystal structure of phosphonium carboxylate complexes. The role of the metal coordination geometry, ligand conformation and hydrogen bonding, CrystEngComm 16 (2014), S. 9010-9024. 81) R. Ganesh, G. Baskaran, J. van den Brink, D.V. Efremov, Theoretical prediction of a time-reversal broken chiral superconducting phase driven by electronic correlations in a single TiSe2 layer, Physical Review Letters 113 (2014) Nr. 17, S. 177001/1-5. 82) J. Gao, P. Ngene, M. Herrich, W. Xia, O. Gutfleisch, M. Muhler, K.P. de Jong, P.E. de Jongh, Interface effects in NaAlH4-carbon nanocomposites for hydrogen storage, International Journal of Hydrogen Energy 39 (2014) Nr. 19, S. 10175-10183. 83) P. Gargarella, S. Pauly, M. Samadi Khoshkhoo, U. Kuehn, J. Eckert, Phase formation and mechanical properties of Ti-Cu-Ni-Zr bulk metallic glass composites, Acta Materialia 65 (2014), S. 259-269. 84) C. Gautham, D.W. Snoke, A. Rastelli, O.G. Schmidt, Time-resolved two-photon excitation of dark states in quantum dots, Applied Physics Letters 104 (2014) Nr. 14, S. 143114/1-4. 85) A. Gebert, P.F. Gostin, R. Sueptitz, S. Oswald, S. Abdi, M. Uhlemann, J. Eckert, Polarization studies of Zr-based bulk metallic glasses for electrochemical machining, Journal of The Electrochemical Society 161 (2014), S. E66-E73. 86) D. Geissler, J. Freudenberger, A. Kauffmann, S. Martin, D. Rafaja, Assessment of the thermodynamic dimension of the stacking fault energy, Philosophical Magazine 94 (2014) Nr. 26, S. 2967-2979. 87) F. German, A. Hintennach, A. LaCroix, D. Thiemig, S. Oswald, F. Scheiba, M.J. Hoffmann, H. Ehrenberg, Influence of temperature and upper cut-off voltage on the formation of lithium-ion cells, Journal of Power Sources 264 (2014), S. 100-107. 88) Q.D. Gibson, D. Evtushinsky, A.N. Yaresko, V.B. Zabolotnyy, M.N. Ali, M.K. Fuccillo, J. van den Brink, B. Buechner, R.J. Cava, S.V. Borisenko, Quasi one dimensional dirac electrons on the surface of Ru2Sn3, Scientific Reports 4 (2014), S. 5168/1-6. 89) S. Giudicatti, S.M. Marz, L. Soler, A. Madani, M.R. Jorgensen, S. Sanchez, O.G. Schmidt, Photoactive rolled-up TiO2 microtubes: Fabrication, characterization and applications, Journal of Materials Chemistry C 2 (2014), S. 5892-5901. 90) M. Gong, B. Hofer, E. Zallo, R. Trotta, J.-W. Luo, O.G. Schmidt, C. Zhang, Statistical properties of exciton fine structure splitting and polarization angles in quantum dot ensembles, Physical Review B 89 (2014) Nr. 20, S. 205312/1-6. 91) C. Gonzalez-Gago, P. Smid, T. Hofmann, C. Venzago, V. Hoffmann, W. Gruner, The use of matrix-specific calibrations for oxygen in analytical glow discharge spectrometry, Analytical and Bioanalytical Chemistry 406 (2014), S. 7473-7482. 92) I.G. Gonzalez-Martinez, S.M. Gorantla, A. Bachmatiuk, V. Bezugly, J. Zhao, T. Gemming, J. Kunstmann, J. Eckert, G. Cuniberti, M.H. Ruemmeli, Room temperature in situ growth of B/BOx nanowires and BOx nanotubes, Nano Letters 14 (2014), S. 799-805. 93) S. Gorantla, A. Bachmatiuk, J. Hwang, H.A. Alsalman, J.Y. Kwak, T. Seyller, J. Eckert, M.G. Spencer, M.H. Ruemmeli, A universal transfer route for graphene, Nanoscale 6 (2014), S. 889-896. 94) P.F. Gostin, H. Wendrock, I. Schneider, M. Bleckmann, M. Stoica, U. Kuehn, J. Eckert, Microstructure and mechanical properties of a newly developed high strength Mg54.7Cu11.5Ag3.3Gd5.5Sc25 alloy, Intermetallics 45 (2014), S. 84-88. 95) H.-J. Grafe, U. Graefe, A.P. Dioguardi, N.J. Curro, S. Aswartham, S. Wurmehl, B. Buechner, Identical spin fluctuations in Cu- and Co- doped BaFe2As2 independent of electron doping, Physical Review B 90 (2014) Nr. 9, S. 94519/1-8. 96) D. Grimm, R.B. Wilson, B. Teshome, S. Gorantla, M.H. Ruemmeli, T. Bublat, E. Zallo, G. Li, D.G. Cahill, O.G. Schmidt, Thermal conductivity of mechanically joined semiconducting/metal nanomembrane superlattices, Nano Letters 14 (2014), S. 2387-2393. 97) V. Grinenko, D.V. Efremov, S.-L. Drechsler, S. Aswartham, D. Gruner, M. Roslova, I. Morozov, K. Nenkov, S. Wurmehl, A.U.B. Wolter, B. Holzapfel, B. Buechner, Superconducting specific-heat jump delta Cel - Tc beta (beta-2) for K1-x NaxFe2As2, Physical Review B 89 (2014) Nr. 6, S. 60504(R)/1-5. 98) V. Grinenko, W. Schottenhamel, A.U.B. Wolter, D.V. Efremov, S.-L. Drechsler, S. Aswartham, M. Kumar, S. Wurmehl, M. Roslova, I.V. Morozov, B. Holzapfel, B. Buechner, E. Ahrens, S.I. Troyanov, S. Koehler, E. Gati, S. Knoener, N.H. Hoang, M. Lang, F. Ricci, G. Profeta, Superconducting properties of K1-xNaxFe2As2 under pressure, Physical Review B 90 (2014) Nr. 9, S. 94511/1-12. 99) M.E. Gruner, S. Faehler, P. Entel, Magnetoelastic coupling and the formation of adaptive martensite in magnetic shape memory alloys, Physica Status Solidi B 251 (2014) Nr. 10, S. 2067-2079. 100) J. Gubicza, Z. Hegedus, J.L. Labar, V. Subramanya Sarma, A. Kauffmann, J. Freudenberger, Microstructure evolution during annealing of an SPD processed supersaturated Cu- 3 at, % Ag alloy, IOP Conference Series: Materials Science and Engineering 63 (2014), S. 12091/1-9. Publications 2014 87

101) M. Guenther, S. Kamusella, R. Sarkar, T. Goltz, H. Luetkens, G. Pascua, S.-H. Do, K.-Y. Choi, H.D. Zhou, C.G.F. Blum, S. Wurmehl, B. Buechner, H.-H. Klauss, Magnetic order and spin dynamics in La2O2Fe2OSe2 probed by 57Fe Moessbauer, 139La NMR, and muon-spin relaxation spectroscopy, Physical Review B 90 (2014) Nr. 18, S. 184408/1-8. 102) E.J. Guo, S. Das, A. Herklotz, Enhancement of switching speed of BiFeO3 capacitors by magnetic fields, APL Materials 2 (2014), S. 96107/1-8. 103) E.J. Guo, R. Roth, S. Das, K. Doerr, Strain induced low mechanical switching force in ultrathin PbZr0.2Ti0.8O3 films, Applied Physics Letters 105 (2014) Nr. 1, S. 12903/1-5. 104) F. Haag, D. Beitelschmidt, J. Eckert, K. Durst, Influences of residual stresses on the serrated flow in bulk metallic glass under elastostatic four-point bending – A nanoindentation and atomic force microscopy study, Acta Materialia 70 (2014), S. 188-197. 105) J. Haenisch, K. Iida, F. Kurth, T. Thersleff, S. Trommler, E. Reich, R. Huehne, L. Schultz, B. Holzapfel, The effect of 45° grain boundaries and associated Fe particles on Jc and resistivity in Ba(Fe0.9Co0.1)2As2 thin films, AIP Conference Proceedings 1574 (2014), S. 260-267. 106) F. Haidu, G. Salvan, D.R.T. Zahn, L. Smykalla, M. Hietschold, M. Knupfer, Transport band gap opening at metal-organic interfaces, Journal of Vacuum Science and Technology A 32 (2014) Nr. 4, S. 40602/1-8. 107) S. Haindl, M. Kidszun, S. Oswald, C. Hess, B. Buechner, S. Koelling, L. Wilde, T. Thersleff, V.V. Yurchenko, M. Jourdan, H. Hiramatsu, H. Hosono, Thin film growth of Fe-based superconductors: From fundamental properties to functional devices. A comparative review, Reports on Progress in Physics 77 (2014), S. 46502/1-32. 108) C. Hamann, R. Mattheis, I. Moench, J. Fassbender, L. Schultz, J. McCord, Magnetization dynamics of magnetic domain wall imprinted magnetic films, New Journal of Physics 16 (2014), S. 23010/1-12. 109) F. Hammerath, E.M. Bruening, S. Sanna, Y. Utz, N.S. Beesetty, R. Saint-Martin, A. Revcolevschi, C. Hess, B. Buechner, H.-J. Grafe, Spin gap in the single spin-12 chain cuprate Sr1.9Ca0.1CuO3, Physical Review B 89 (2014) Nr. 18, S. 184410/1-5. 110) J.H. Han, N. Mattern, U. Vainio, A. Shariq, S.W. Sohn, D.H. Kim, J. Eckert, Phase separation in Zr56-xGdxCo28Al16 metallic glasses (0< x < 20), Acta Materialia 66 (2014), S. 262-272. 111) A. Helth, P.F. Gostin, S. Oswald, H. Wendrock, U. Wolff, U. Hempel, S. Arnhold, M. Calin, J. Eckert, A. Gebert, Chemical nanoroughening of Ti40Nb surfaces and its effect on human mesenchymal stromal cell response, Journal of Biomedical Materials Research, Part B - Applied Biomaterials 102 B (2014), S. 31-41. 112) N. Heming, U. Treske, M. Knupfer, B. Buechner, D.S. Inosov, N.Y. Shitsevalova, V.B. Filipov, S. Krause, A. Koitzsch, Surface properties of SmB6 from x-ray photoelectron spectroscopy, Physical Review B 90 (2014) Nr. 19, S. 195128/1-7. 113) C. Hengst, M. Wolf, R. Schaefer, L. Schultz, J. McCord, Acoustic-domain resonance mode in magnetic closure-domain structures: A probe for domain-shape characteristics and domain-wall transformations, Physical Review B 89 (2014) Nr. 21, S. 214412/1-6. 114) A. Herklotz, M.D. Biegalski, H.M. Christen, E.-J. Guo, K. Nenkov, A.D. Rata, L. Schultz, K. Doerr, Strain response of magnetic order in perovskite-type oxide films, Philosophical Transactions of the Royal Society A 372 (2014), S. 20120441/ 1-12. 115) M. Herklotz, F. Scheiba, R. Glaum, E. Mosymow, S. Oswald, J. Eckert, H. Ehrenberg, Electrochemical oxidation of trivalent chromium in a phosphatematrix: Li3Cr2(PO4)3as cathode material for lithium ion batteries, Electrochimica Acta 139 (2014), S. 356-364. 116) H. Hermann, Sung Nok Chiu et al.: Stochastic geometry and its applications, Physik-Journal (2014) Nr. 9, S. 75. 117) H. Hermann, A. Elsner, Geometric models for isotropic random porous media: A review, Advances in Materials Science and Engineering (2014), S. 1-16. 118) H. Hermann, U. Kuehn, H. Wendrock, V. Kokotin, B. Schwarz, Evidence for cooling-rate-dependent icosahedral short-range order in a Cu-Zr-Al metallic glass, Journal of Applied Crystallography 47 (2014), S. 1906-1911. 119) A.-K. Herrmann, P. Formanek, L. Borchardt, M. Klose, L. Giebeler, J. Eckert, S. Kaskel, N. Gaponik, A. Eychmueller, Multimetallic aerogels by template-free self-assembly of Au, Ag, Pt, and Pd nanoparticles, Chemistry of Materials 26 (2014), S. 1074-1083. 120) C. Hoffmann, T. Biemelt, M.R. Lohe, M.H. Ruemmeli, S. Kaskel, Nanoporous and highly active Silicon carbide supported CeO2-catalysts for the Methane oxidation reaction, Small 10 (2014), S. 316-322. 121) M. Hossain, A. Abdkader, C. Cherif, M. Sparing, D. Berger, G. Fuchs, L. Schultz, Innovative twisting mechanism based on superconducting technology in a ring-spinning system, Textile Research Journal 84 (2014) Nr. 8, S. 871-880. 122) L. Hozoi, H. Gretarsson, J.P. Clancy, B.-G. Jeon, B. Lee, K.H. Kim, V. Yushankhai, P. Fulde, D. Casa, T. Gog, J. Kim, A.H. Said, M.H. Upton, Y.-J. Kim, J. van den Brink, Longer-range lattice anisotropy strongly competing with spin-orbit interactions in pyrochlore iridates, Physical Review B 89 (2014) Nr. 11, S. 115111/1-6. 123) G. Hrkac, K. Butler, T.G. Woodcock, L. Saharan, T. Schrefl, O. Gutfleisch, Modeling of Nd-Oxide grain boundary phases in Nd-Fe-B sintered magnets, JOM 66 (2014) Nr. 7, S. 1138-1143. 124) G. Hrkac, T.G. Woodcock, K.T. Butler, L. Saharan, M.T. Bryan, T. Schrefl, O. Gutfleisch, Impact of different Nd-rich crystal-phases on the coercivity of Nd-Fe-B grain ensembles, Scripta Materialia 70 (2014), S. 35-38. 125) Y.H. Huo, V. Krapek, A. Rastelli, O.G. Schmidt, Volume dependence of excitonic fine structure splitting in geometrically similar quantum dots, Physical Review B 90 (2014) Nr. 4, S. 41304(R)/1-4. 126) Y.H. Huo, B.J. Witek, S. Kumar, J.R. Cardenas, J.X. Zhang, N. Akopian, R. Singh, E. Zallo, R. Grifone, D. Kriegner, R. Trotta, F. Ding, J. Stangl, V. Zwiller, G. Bester, A. Rastelli, O.G. Schmidt, A light-hole exciton in a quantum dot, nature physics 10 (2014), S. 46-51. 127) V. Hutanu, A.P. Sazonov, M. Meven, G. Roth, A. Gukasov, H. Murakawa, Y. Tokura, D. Szaller, S. Bordacs, I. Kezsmarki, V.K. Guduru, L.C.J.M. Peters, U. Zeitler, J. Romhanyi, B. Nafradi, Evolution of two-dimensional antiferromagnetism with temperature and magnetic field in multiferroic Ba2CoGe2O7, Physical Review B 89 (2014) Nr. 6, S. 64403/1-9. 128) A. Ichinose, I. Tsukada, F. Nabeshima, Y. Imai, A. Maeda, F. Kurth, B. Holzapfel, K. Iida, S. Ueda, M. Naito, Induced lattice strain in epitaxial Fe-based superconducting films on CaF2 substrates: A comparative study of the microstructures of SmFeAs(O,F), Ba(Fe,Co)2As2, and FeTe0.5Se0.5, Applied Physics Letters 104 (2014) Nr. 12, S. 122603/1-5. 88 Publications 2014

129) K.R. Idzik, T. Licha, V. Lukes, P. Rapta, J. Frydel, M. Schaffer, E. Taeuscher, R. Beckert, L. Dunsch, Synthesis and optical properties of various thienyl derivatives of pyrene, Journal of Fluorescence 24 (2014) Nr. 1, S. 153-160. 130) B. Idzikowski, Z. Sniadecki, M. Reiffers, U.K. Roessler, Glass-forming ability for selected quasi-ternary metallic system: Magnetism and heat capacity, Journal of Non-Crystalline Solids 383 (2014), S. 2-5. 131) K. Iida, F. Kurth, M. Chihara, N. Sumiya, V. Grinenko, A. Ichinose, I. Tsukada, J. Haenisch, V. Matias, T. Hatano, B. Holzapfel, H. Ikuta, Highly textured oxypnictide superconducting thin films on metal substrates, Applied Physics Letters 105 (2014) Nr. 17, S. 172602/1-. 132) J.J. Ipus, J.S. Blazquez, V. Franco, M. Stoica, A. Conde, Milling effects on magnetic properties of melt spun Fe-Nb-B alloy, Journal of Applied Physics 115 (2014) Nr. 17, S. 17B518/1-3. 133) F.A. Javid, N. Mattern, M. Samadi Khoshkhoo, M. Stoica, S. Pauly, J. Eckert, Phase formation of Cu50xCoxZr50 (x = 0–20 at.%) alloys: Influence of cooling rate, Journal of Alloys and Compounds 590 (2014), S. 428-434. 134) Y. Jia, F. Cao, S. Scudino, P. Ma, H. Li, L. Yu, J. Eckert, J. Sun, Microstructure and thermal expansion behavior of spray-deposited Al–50Si, Materials and Design 57 (2014), S. 585-591. 135) L. Jin, Y. Shuai, X. Ou, P.F. Siles, H.Z. Zeng, T. You, N. Du, D. Buerger, I. Skorupa, S. Zhou, W.B. Luo, C.G. Wu, W.L. Zhang, T. Mikolajick, O.G. Schmidt, H. Schmidt, Resistive switching in unstructured, polycrystalline BiFeO3 thin films with downscaled electrodes, Physica Status Solidi A 211 (2014) Nr. 11, S. 2563-2568. 136) Y.I. Joe, X.M. Chen, P. Ghaemi1, K.D. Finkelstein, G.A. de la Pena, Y. Gan, J.C.T. Lee, S. Yuan, J. Geck, G.J. MacDougall, T.C. Chiang, S.L. Cooper, E. Fradkin, P. Abbamonte, Emergence of charge density wave domain walls above the superconducting dome in 1T-TiSe2, nature physics 10 (2014), S. 421-425. 137) S. Johnston, M. Abdel-Hafiez, L. Harnagea, V. Grinenko, D. Bombor, Y. Krupskaya, C. Hess, S. Wurmehl, A.U.B. Wolter, B. Buechner, H. Rosner, S.-L. Drechsler, Specific heat of Ca0.32Na0.68Fe2As2 single crystals: Unconventional s +- multiband superconductivity with intermediate repulsive interband coupling and sizable attractive intraband couplings, Physical Review B 89 (2014) Nr. 13, S. 134507/1-11. 138) P. Jovari, P. Lucas, Z. Yang, B. Bureau, I. Kaban, B. Beuneu, J. Bednarcik, Short-range order in Ge-As-Te glasses, Journal of the American Ceramic Society 97 (2014) Nr. 5, S. 1625-1632. 139) H.Y. Jung, M. Stoica, S. Yi, D.H. Kim, J. Eckert, Electrical and magnetic properties of Fe-based bulk metallic glass with minor Co and Ni addition, Journal of Magnetism and Magnetic Materials 364 (2014), S. 80-84. 140) H.Y. Jung, S. Yi, Nanocrystallization and soft magnetic properties of Fe23M6 (M: C or B) phase in Fe-based bulk metallic glass, Intermetallics 49 (2014), S. 18-22. 141) S. Just, S. Zimmermann, V. Kataev, B. Buechner, M. Pratzer, M. Morgenstern, Preferential antiferromagnetic coupling of vacancies in graphene on SiO2: Electron spin resonance and scanning tunneling spectroscopy, Physical Review B 90 (2014) Nr. 12, S. 125449/1-9. 142) I. Kaban, P. Jovari, A. Waske, M. Stoica, J. Bednarcik, B. Beuneu, N. Mattern, J. Eckert, Atomic structure and magnetic properties of Fe-Nb-B metallic glasses, Journal of Alloys and Compounds 586 (2014) Nr. Suppl. 1, S. S189-S193. 143) I. Kaban, K. Khalouk, F. Gasser, J.-G. Gasser, J. Bednarcik, O. Shuleshova, I. Okulov, T. Gemming, N. Mattern, J. Eckert, In situ studies of temperature-dependent behaviour and crystallisation of Ni36.5Pd36.5P27 metallic glass, Journal of Alloys and Compounds 615 (2014), S. S208-S212. 144) M. Kalbac, V. Vales, L. Kavan, L. Dunsch, Doping of C70 fullerene peapods with lithium vapor: Raman spectroscopic and Raman spectroelectrochemical studies, Nanotechnology 25 (2014) Nr. 48, S. 485706/1-7. 145) D. Karnaushenko, D. Makarov, M. Stoeber, D.D. Karnaushenko, S. Baunack, O.G. Schmidt, High-performance magnetic sensorics for printable and flexible electronics, Advanced Materials online first (2014). 146) F. Karnbach, M. Uhlemann, A. Gebert, J. Eckert, K. Tschulik, Magnetic field templated patterning of the soft magnetic alloy CoFe, Electrochimica Acta 123 (2014), S. 477-484. 147) T. Kaspar, J. Fiedler, I. Skorupa, D. Buerger, O.G. Schmidt, H. Schmidt, Transport in ZnCoO thin films with stable bound magnetic polarons, APL Materials 2 (2014), S. 76101/1-7. 148) S.O. Katterwe, T. Jacobs, A. Maljuk, V.M. Krasnov, Low anisotropy of the upper critical field in a strongly anisotropic layered cuprate Bi2.15Sr1.9CuO6+ delta: Evidence for a paramagnetically limited superconductivity, Physical Review B 89 (2014) Nr. 21, S. 214516/1-11. 149) V.M. Katukuri, S. Nishimoto, V. Yushankhai, A. Stoyanova, H. Kandpal, S. Choi, R. Coldea, I. Rousochatzakis, L. Hozoi, J. van den Brink, Kitaev interactions between j = 1/2 moments in honeycomb Na2IrO3 are large and ferromagnetic: Insights from ab initio quantum chemistry calculations, New Journal of Physics 16 (2014), S. 13056/1-13. 150) V.M. Katukuri, V. Yushankhai, L. Siurakshina, J. van den Brink, L. Hozoi, I. Rousochatzakis, Mechanism of Basal-Plane antiferromagnetism in the Spin-Orbit driven Iridate Ba2IrO4, Physical Review X 4 (2014), S. 21051/1-10. 151) V.M. Katukuri, K. Roszeitis, V. Yushankhai, A. Mitrushchenkov, H. Stoll, M. van Veenendaal, P. Fulde, J. van den Brink, L. Hozoi, Electronic structure of low-dimensional 4d5 oxides: Interplay of ligand distortions, overall lattice anisotropy, and spin-orbit interactions, Inorganic Chemistry 53 (2014), S. 4833-4839. 152) S. Kauffmann-Weiss, S. Hamann, L. Reichel, A. Siegel, V. Alexandrakis, R. Heller, L. Schultz, A. Ludwig, S. Faehler, The Bain library: A Cu-Au buffer template for a continuous variation of lattice parameters in epitaxial films, APL Materials 2 (2014), S. 46107/1-6. 153) D. Keller, S. Buecheler, P. Reinhard, F. Pianezzi, D. Pohl, A. Surrey, B. Rellinghaus, R. Erni, A.N. Tiwari, Local band gap measurements by VEELS of thin film solar cells, Microscopy and Microanalysis 20 (2014), S. 1246-1253. 154) I.S.M. Khalil, V. Magdanz, S. Sanchez, O.G. Schmidt, S. Misra, The control of self-propelled microjets inside a microchannel with time-varying flow rates, IEEE Transactions on Robotics 30 (2014) Nr. 1, S. 49-58. Publications 2014 89

155) I.S.M. Khalil, V. Magdanz, S. Sanchez, O.G. Schmidt, S. Misra, Wireless magnetic-based closed-loop control of self-propelled microjets, PLOS one 9 (2014) Nr. 2, S. e83053/1-6. 156) I.S.M. Khalil, V. Magdanz, S. Sanchez, O.G. Schmidt, S. Misra, Biocompatible, accurate, and fully autonomous: A sperm-driven micro-bio-robot, Journal of Micro-Bio Robotics 9 (2014) Nr. 3-4, S. 79-86. 157) S.M. Khoshkhoo, S. Scudino, J. Bednarcik, A. Kauffmann, H. Bahmanpour, J. Freudenberger, R. Scattergood, M.J. Zehetbauer, C.C. Koch, J. Eckert, Mechanism of nanostructure formation in ball-milled Cu and Cu–3wt%Zn studied by X-ray diffraction line profile analysis, Journal of Alloys and Compounds 588 (2014), S. 138-143. 158) W. Kicinski, M. Bystrzejewski, M.H. Ruemmeli, T. Gemming, Porous graphitic materials obtained from carbonization of organic xerogels doped with transition metal salts, Bulletin of Materials Science 37 (2014) Nr. 1, S. 141-150. 159) J. Kim, M. Daghofer, A.H. Said, T. Gog, J. van den Brink, G. Khaliullin, B.J. Kim, Excitonic quasiparticles in a spin-orbit Mott insulator, nature communications 5 (2014), S. 4453/1-6. 160) M. Klose, I. Lindemann, C. Bonatto Minella, K. Pinkert, M. Zier, L. Giebeler, P. Nolis, M.D. Baro, S. Oswald, O. Gutfleisch, H. Ehrenberg, J. Eckert, Unusual oxidation behavior of light metal hydride by tetrahydrofuran solvent molecules confined in ordered mesoporous carbon, Journal of Materials Research 29 (2014) Nr. 1, S. 55-63. 161) M. Klose, K. Pinkert, M. Zier, M. Uhlemann, F. Wolke, T. Jaumann, P. Jehnichen, D. Wadewitz, S. Oswald, J. Eckert, L. Giebeler, Hol- low carbon nano-onions with hierarchical porosity derived from commercial metal organic framework, Carbon 79 (2014), S. 302-309. 162) B. Koch, S. Sanchez, C.K. Schmidt, A. Swiersy, S.P. Jackson, O.G. Schmidt, Confi nement and deformation of single cells and their nuclei inside size-adapted microtubes, Advanced Healthcare Materials 3 (2014), S. 1753-1758. 163) M. Kohl, M. Schmitt, A. Backen, L. Schultz, B. Krevet, S. Faehler, Ni-Mn-Ga shape memory nanoactuation, Applied Physics Letters 104 (2014) Nr. 4, S. 43111/1-5. 164) A. Krause, W.M. Weber, Pohl D., B. Rellinghaus, M. Verheijen, T. Mikolajick, Investigation of embedded perovskite nanoparticles for enhanced capacitor permittivities, ACS Applied Materials and Interfaces 6 (2014), S. 19737-19743. 165) K.J. Krause, K. Mathwig, B. Wolfrum, S.G. Lemay, Brownian motion in electrochemical nanodevices, The European Physical Journal Special Topics 223 (2014) Nr. 14, S. 3165-3178. 166) M. Krautz, J. Hosko, K. Skokov, P. Svec, M. Stoica, L. Schultz, J. Eckert, O. Gutfleisch, A. Waske, Pathways for novel magnetocaloric materials: A processing prospect, Physica Status Solidi (c) 11 (2014) Nr. 5-6, S. 1039-1042. 167) S. Kudela, K. Izdinsky, S. Oswald, P. Ranachowski, Z. Ranachowski, S. Kudela, Decomposition of silica binder during infiltration of Saffil fiber preform with Mg and Mg-Li melts, Kovove Materialy - Metallic Materials 52 (2014) Nr. 4, S. 183-188. 168) P. Kumar, D.V.S. Muthu, L. Harnagea, S. Wurmehl, B. Buechner, A.K. Sood, Phonon anomalies, orbital-ordering and electronic raman scattering in iron-pnictide Ca(Fe0.97Co0.03)2As2: Temperature-dependent Raman study, Journal of Physics: Condensed Matter 26 (2014) Nr. 30, S. 305403/1-5. 169) S. Kumar, L. Harnagea, S. Wurmehl, B. Buechner, A.K. Sood, Signatures of superconducting and pseudogap phases in ultrafast transient reflectivity of Ca (Fe0.927Co0.073) 2As2, epl 105 (2014) Nr. 4, S. 47004/1-6. 170) S. Kumar, E. Zallo, Y.H. Liao, P.Y. Lin, R. Trotta, P. Atkinson, J.D. Plumhof, F. Ding, B.D. Gerardot, S.J. Cheng, A. Rastelli, O.G. Schmidt, Anomalous anticrossing of neutral exciton states in GaAs/AlGaAs quantum dots, Physical Review B 89 (2014) Nr. 11, S. 115309/1-10. 171) J. Lach, A. Jeremies, D. Breite, B. Abel, B. Mahns, M. Knupfer, V. Matulis, O.A. Ivashkevich, B. Kersting, Encapsulation of the 4-mercaptobenzoate ligand by macrocyclic metal complexes: Conversion of a metallocavitand to a metalloligand, Inorganic Chemistry 53 (2014), S. 10825-10834. 172) M.H. Lee, B.S. Kim, D.H. Kim, R.T. Ott, F. Sansoz, J. Eckert, Effect of geometrical constraint condition on the formation of nanoscale twins in the Ni-based metallic glass composite, Philosophical Magazine Letters 94 (2014) Nr. 6, S. 351-360. 173) M.H. Lee, E.S. Park, R.T. Ott, B.S. Kim, J. Eckert, Evaluation of the relationship between the effective strain and the springback behavior during the deformation of metallic glass ribbons, Applied Physics Letters 105 (2014) Nr. 6, S. 61906/1-3. 174) S.W. Lee, J.T. Kim, S.H. Hong, H.J. Park, J.-Y. Park, N.S. Lee, Y. Seo, J.Y. Suh, J. Eckert, D.H. Kim, J.M. Park, K.B. Kim, Micro-to-nano-scale deformation mechanisms of a bimodal ultrafine eutectic composite, Scientific Reports 4 (2014), S. 6500/1-5. 175) A. Leifert, G. Mondin, S. Doerfler, S. Hampel, S. Kaskel, E. Hofmann, J. Zschetzsche, E. Pflug, G. Dietrich, M. Ruehl, S. Braun, S. Schaedlich, Fabrication of nanoparticle-containing films and nano layers for alloying and joining, Advanced Engineering Materials 16 (2014) Nr. 10, S. 1264-1269. 176) K. Li, C. Song, Q. Zhai, M. Stoica, J. Eckert, Microstructure evolution of gas-atomized Fe- 6.5 wt% Si droplets, Journal of Materials Research 29 (2014) Nr. 4, S. 527-534. 177) G. Lin, D. Makarov, M. Melzer, W. Si, C. Yan, O.G. Schmidt, A highly flexible and compact magnetoresistive analytic device, Lab on a Chip 14 (2014), S. 4050-4058. 178) S. Lindner, B. Mahns, U. Treske, O. Vilkov, F. Haidu, M. Fronk, D.R.T. Zahn, M. Knupfer, Epitaxial growth and electronic properties of well ordered phthalocyanine heterojunctions MnPc/F16CoPc, The Journal of Chemical Physics 141 (2014), S. 94706/1-5. 179) A Liska, M. Rosenkranz, J. Klima, L. Dunsch, P. Lhotak, J. Ludvik, Formation and proof of stable bi-, tri- and tetraradical polyanions during the electrochemical reduction of cone-polynitrocalix[4]arenes. An ESR-UV-vis spectroelectrochemical study, Electrochimica Acta 140 (2014), S. 572-578. 180) X. Liu, W. Si, J. Zhang, X. Sun, J. Deng, S. Baunack, S. Oswald, L. Liu, C. Yan, O.G. Schmidt, Free-standing Fe2O3 nanomembranes enabling ultra-long cycling life and high rate capability for Li-ion batteries, Scientific Reports 4 (2014), S. 7452/1-8. 181) L. Loeber, F.P. Schimansky, U. Kuehn, F. Pyczak, J. Eckert, Selective laser melting of a beta-solidifying TNM-B1 titanium aluminide alloy, Journal of Materials Processing Technology 214 (2014) Nr. 9, S. 1852-1860. 90 Publications 2014

182) M. Luckabauer, U. Kuehn, J. Eckert, W. Sprengel, Specific volume study of a bulk metallic glass far below its calorimetrically determined glass transition temperature, Physical Review B 89 (2014) Nr. 17, S. 174113/1-6. 183) L. Ma, D.A. Gilbert, V. Neu, R. Schaefer, J.G. Zheng, X.Q. Yan, Z. Shi, K. Liu, S.M. Zhou, Magnetization reversal in perpendicularly magnetized L10 FePd/FePt heterostructures, Journal of Applied Physics 116 (2014) Nr. 3, S. 33922/1-7. 184) P. Ma, K.G. Prashanth, S. Scudino, Y. Jia, H. Wang, C. Zou, Z. Wei, J. Eckert, Influence of annealing on mechanical properties of Al- 20Si processed by selective laser melting, metals 4 (2014), S. 28-36. 185) P. Ma, C.M. Zou, H.W. Wang, S. Scudino, B.G. Fu, Z.J. Wei, U. Kuehn, J. Eckert, Effects of high pressure and SiC content on microstructure and precipitation kinetics of Al–20Si alloy, Journal of Alloys and Compounds 586 (2014), S. 639-644. 186) P. Machata, P. Rapta, V. Lukes, K.R. Idzik, T. Licha, R. Beckert, L. Dunsch, Regioregular electrochromic polymers based on thienyl derivatives of fluorescent pyrene monomers: Optical properties, spectroelectrochemistry and quantum chemical study, Electrochimica Acta 122 (2014), S. 57-65. 187) A. Madani, S. Boettner, M.R. Jorgensen, O.G. Schmidt, Rolled-up TiO2 optical microcavities for telecom and visible photonics, Optics Letters 39 (2014) Nr. 2, S. 189-192. 188) V. Magdanz, M. Guix, O.G. Schmidt, Tubular micromotors: from microjets to spermbots, Robotics and Biomimetics 1 (2014) Nr. 11, S. 1-10. 189) V. Magdanz, O.G. Schmidt, Spermbots: Potential impact for drug delivery and assisted reproductive technologies (Editorial), informa Healthcare (2014), S. 1125-1129. 190) V. Magdanz, G. Stoychev, L. Ionov, S. Sanchez, O.G. Schmidt, Stimuli-responsive microjets with reconfigurable shape, Angewandte Chemie - International Edition 53 (2014) Nr. 10, S. 2673-2677. 191) B. Mahns, O. Kataeva, D. Islamov, S. Hampel, F. Steckel, C. Hess, M. Knupfer, B. Buechner, C. Himcinschi, T. Hahn, R. Renger, J. Kortus, Crystal growth, structure, and transport properties of the charge-transfer salt picene/2,3,5,6-tetrafluoro-7,7,8,8- tetra- cyanoquinodimethane, Crystal Growth and Design 14 (2014), S. 1338-1346. 192) S. Makharza, O. Vittorio, G. Cirillo, S. Oswald, E. Hinde, M. Kavallaris, B. Buechner, M. Mertig, S. Hampel, Graphene oxide - Gelatin nanohybrids as functional tools for enhanced carboplatin activity in neuroblastoma cells, Pharmaceutical Research online first (2014). 193) L.A.B. Marcal, B.L.T. Rosa, G.A.M. Safar, R.O. Freitas, O.G. Schmidt, P.S.S. Guimaraes, C. Deneke, A. Malachias, Observation of emission enhancement caused by symmetric carrier depletion in III-V nanomembrane heterostructures, ACS Photonics 1 (2014), S. 863-870. 194) D. Marko, K.G. Prashanth, S. Scudino, Z. Wang, N. Ellendt, V. Uhlenwinkel, J. Eckert, Al-based metal matrix composites reinforced with Fe49.9Co35.1Nb7.7B4.5Si2.8 glassy powder: Mechanical behavior under tensile loading, Journal of Alloys and Compounds 615 (2014), S. S382-S385. 195) T. Marr, J. Freudenberger, V. Maier, H.W. Hoeppel, M. Goeken, L. Schultz, The strengthening effect of phase boundaries in a severely plastically deformed Ti-Al composite wire, metals 4 (2014), S. 37-54. 196) M.L. Martine, G. Parzych, F. Thoss, L. Giebeler, J. Eckert, Na-Sb-Sn ternary phase diagram at room temperature for potential anode materials in sodium-ion batteries, Solid State Ionics 268 (2014), S. 261-264. 197) C.S. Martinez-Cisneros, S. Sanchez, W. Xi, O.G. Schmidt, Ultracompact three-dimensional tubular conductivity microsensors for ionic and biosensing applications, Nano Letters 14 (2014), S. 2219-2224. 198) N. Mattern, Comment on - Thermal expansion measurements by X-ray scattering and breakdown of Ehrenfest’s relation in alloy liquids - Appl. Phys. Lett. 104, 191907 (2014), Applied Physics Letters 105 (2014) Nr. 25, S. 256101/1-2. 199) N. Mattern, J.H. Han, K.G. Pradeep, K.C. Kim, E.M. Park, D.H. Kim, Y. Yokoyama, D. Raabe, J. Eckert, Structure of rapidly quenched (Cu0.5Zr0.5)100xAgx alloys (x = 0–40 at.%), Journal of Alloys and Compounds 607 (2014), S. 285-290. 200) N. Mattern, Y. Yokoyama, A. Mizuno, J.H. Han, O. Fabrichnaya, T. Harada, S. Kohara, J. Eckert, Experimental and thermodynamic assessment of the Nd-Zr system, CALPHAD: Computer Coupling of Phase Diagrams and Thermochemistry 46 (2014), S. 103-107. 201) N. Mattern, Y. Yokoyama, A. Mizuno, J.H. Han, O. Fabrichnaya, T. Harada, S. Kohara, J. Eckert, Experimental and thermodynamic assessment of the Nd-Ti system, CALPHAD: Computer Coupling of Phase Diagrams and Thermochemistry 47 (2014), S. 136-143. 202) N. Mattern, Y. Yokoyama, A. Mizuno, J.H. Han, O. Fabrichnaya, H. Wendrock, T. Harada, S. Kohara, J. Eckert, Experimental and thermodynamic assessment of the Ce-Zr system, CALPHAD: Computer Coupling of Phase Diagrams and Thermochemistry 46 (2014), S. 213-219. 203) E.M. Mazzer, C.S. Kiminami, P. Gargarella, R.D. Cava, L.A. Basilio, C. Bolfarini, W.J. Botta, J. Eckert, T. Gustmann, S. Pauly, Atomization and selective laser melting of a Cu-Al-Ni-Mn shape memory alloy, Materials Science Forum 802 (2014), S. 343-348. 204) B. Meana-Esteban, A. Petr, C. Kvarnstroem, A. Ivaska, L. Dunsch, Poly(2-methoxynaphthalene): A spectroelectrochemical study on a fused ring conducting polymer, Electrochimica Acta 115 (2014), S. 10-15. 205) R. Medda, A. Helth, P. Herre, D. Pohl, B. Rellinghaus, N. Perschmann, S. Neubauer, H. Kessler, S. Oswald, J. Eckert, J.P. Spatz, A. Gebert, E.A. Cavalcanti-Adam, Investigation of early cell-surface interactions of human mesenchymal stem cells on nanopatterned beta- type titanium niobium alloy surfaces, Interface Focus 4 (2014) Nr. 1, S. 20130046/1-11. 206) A. Meier, M. Weinberger, K. Pinkert, M. Oschatz, S. Paasch, L. Giebeler, H. Althues, E. Brunner, J. Eckert, S. Kaskel, Silicon oxycarbide-derived carbons from a polyphenylsilsequioxane precursor for supercapacitor applications, Microporous and Mesoporous Materials 188 (2014), S. 140-148. 207) T. Meissner, S.K. Goh, J. Haase, M. Richter, K. Koepernik, H. Eschrig, Nuclear magnetic resonance at up to 10.1 GPa pressure detects an electronic topological transition in aluminum metal, Journal of Physics: Condensed Matter 26 (2014) Nr. 1, S. 15501/1-5. 208) M. Melzer, D. Karnaushenko, G. Lin, S. Baunack, D. Makarov, O.G. Schmidt, Direct transfer of magnetic sensor devices to elastomeric supports for stretchable electronics, Advanced Materials online first (2014). Publications 2014 91

209) M. Melzer, J.I. Moench, D. Makarov, Y. Zabila, G.S.C. Bermudez, D. Karnaushenko, S. Baunack, F. Bahr, C. Yan, M. Kaltenbrunner, O.G. Schmidt, Wearable magnetic field sensors for flexible electronics, Advanced Materials online first (2014). 210) R.G. Mendes, B. Koch, A. Bachmatiuk, A.A. El-Gendy, Y. Krupskaya, A. Springer, R. Klingeler, O. Schmidt, B. Buechner, S. Sanchez, M.H. Ruemmeli, Synthesis and toxicity characterization of carbon coated iron oxide nanoparticles with highly defined size distributions, Biochimica et Biophysica Acta 1840 (2014), S. 160-169. 211) D. Mikhailova, C.Y. Kuo, P. Reichel, A.A. Tsirlin, A. Efimenko, M. Rotter, M. Schmidt, Z. Hu, T.W. Pi, L.Y. Jang, Y.L. Soo, S. Oswald, L.H. Tjeng, Structure, magnetism, and valence states of Cobalt and Platinum in quasi-one-dimensional oxides A3CoPtO6 with A = Ca, Sr, The Journal of Physical Chemistry C 118 (2014), S. 5463-5469. 212) A. Mohan, B. Buechner, S. Wurmehl, C. Hess, Growth of single crystalline delafossite LaCuO2 by the travelling-solvent floating zone method, Journal of Crystal Growth 402 (2014), S. 304-307. 213) A. Mohan, N. Sekhar Beesetty, N. Hlubek, R. Saint-Martin, A. Revcolevschi, B. Buechner, C. Hess, Bond disorder and spinon heat transport in the S= 1/2 Heisenberg spin chain compound Sr 2 CuO 3: From clean to dirty limits, Physical Review B 89 (2014) Nr. 10, S. 104302/1-. 214) M. Moore, R. Sueptitz, A. Gebert, L. Schultz, O. Gutfleisch, Impact of magnetization state on the corrosion of sintered Nd-Fe-B magnets for e-motor applications, Materials and Corrosion 65 (2014) Nr. 9, S. 891-896. 215) F. Mueller, G. Doerfel, Zwischen Wissenschaft und Handwerk - Der Glasinstrumentenbauer Heinrich Geissler und seine Schule, Physik-Journal 13 (2014) Nr. 5, S. 39-42. 216) N.K. Mukhopadhyay, F. Ali, S. Scudino, M. Samadi Khoshkhoo, M. Stoica, V.C. Srivastava, V. Uhlenwinkel, G. Vaughan, C. Suryanarayana, J. Eckert, Inverse Hall-Petch like mechanical behaviour in nanophase AlCuFe quasicrystals: A new phenomenon, Acta Physica Polonica A 126 (2014) Nr. 2, S. 543-548. 217) F.M. Muntyanu, A. Gilewski, K. Nenkov, K. Rogacki, A.J. Zaleski, G. Fuks, V. Chistol, Magnetic properties of bi-, tri- and multicrystals of 3D topological insulator Bi1-x-Sbx ..., Physics Letters A 378 (2014) Nr. 16-17, S. 1213-1216. 218) Y.G. Naidyuk, O.E. Kvitnitskaya, S. Aswartham, G. Fuchs, K. Nenkov, S. Wurmehl, Exploring point-contact spectra of Ba1-xNaxFe2As2 in the normal and superconducting states, Physical Review B 89 (2014) Nr. 10, S. 104512/1-9. 219) Y.G. Naidyuk, O.E. Kvitnitskaya, N.V. Gamayunova, L. Boeri, S. Aswartham, S. Wurmehl, B. Buechner, D.V. Efremov, G. Fuchs, S.-L. andDrechsler, Single 20 meV boson mode in KFe2As2 detected by point-contact spectroscopy, Physical Review B 90 (2014) Nr. 9, S. 94505/1-9. 220) E. Nazarova, K. Buchkov, S. Terzieva, K. Nenkov, A. Zahariev, D. Kovacheva, N. Balchev, G. Fuchs, The effect of Ag addition on the superconducting properties of FeSe0.94 , Journal of Superconductivity and Novel Magnetism online first (2014). 221) R. Niemann, O. Heczko, L. Schultz, S. Faehler, Inapplicability of the Maxwell relation for the quantification of caloric effects in anisotropic ferroic materials, International Journal of Refrigeration 37 (2014), S. 281-288. 222) R. Niemann, J. Kopecek, O. Heczko, J. Romberg, L. Schultz, S. Faehler, E. Vives, L. Manosa, A. Planes, Localizing sources of acoustic emission during the martensitic transformation, Physical Review B 89 (2014) Nr. 21, S. 214118/1-11. 223) I.V. Okulov, M. Boenisch, U. Kuehn, W. Skrotzki, J. Eckert, Significant tensile ductility and toughness in an ultrafine-structured Ti68.8Nb13.6Co6Cu5.1Al6.5 bi-modal alloy, Materials Science and Engineering A 615 (2014), S. 457-463. 224) I.V. Okulov, U. Kuehn, T. Marr, J. Freudenberger, L. Schultz, C.-G. Oertel, W. Skrotzki, J. Eckert, Deformation and fracture behavior of composite structured Ti-Nb-Al-Co(-Ni) alloys, Applied Physics Letters 104 (2014) Nr. 7, S. 71905/1-4. 225) I.V. Okulov, U. Kuehn, T. Marr, J. Freudenberger, I.V. Soldatov, L. Schultz, C.-G. Oertel, W. Skrotzki, J. Eckert, Microstructure and mechanical properties of new composite structured Ti–V–Al–Cu–Ni alloys for spring applications, Materials Science and Engineering A 603 (2014), S. 76-83. 226) I.V. Okulov, U. Kuehn, J. Romberg, I.V. Soldatov, J. Freudenberger, L. Schultz, A. Eschke, C.-G. Oertel, W. Skrotzki, J. Eckert, Mechanical behavior and tensile/compressive strength asymmetry of ultrafine structured Ti-Nb-Ni-Co-Al alloys with bi-modal grain size distribution, Materials and Design 62 (2014), S. 14-20. 227) A. Omar, C.G.F. Blum, W. Loeser, B. Buechner, S. Wurmehl, Effect of annealing on spinodally decomposed Co2CrAl grown via floating zone technique, Journal of Crystal Growth 401 (2014), S. 617-621. 228) M. Oschatz, L. Borchardt, K. Pinkert, S. Thieme, M.R. Lohe, C. Hoffmann, M. Benusch, F.M. Wisser, C. Ziegler, L. Giebeler, M.H. Ruemmeli, J. Eckert, A. Eychmueller, S. Kaskel, Hierarchical carbide-derived carbon foams with advanced mesostructure as a versatile electrochemical energy- storage material, Advanced Energy Materials 4 (2014) Nr. 2, S. 1300645/1-9. 229) S. Oswald, P.-F. Gostin, A. Helth, S. Abdi, L. Giebeler, H. Wendrock, M. Calin, J. Eckert, A. Gebert, XPS and AES sputter-depth profiling at surfaces of biocompatible passivated Ti-based alloys: Concentration quantification considering chemical effects, Surface and Interface Analysis 46 (2014), S. 683-688. 230) S. Oswald, U. Vogel, J. Eckert, ARXPS measurement simulation for improved data interpretation at complex Ta/Li-niobate interfaces, Surface and Interface Analysis 46 (2014), S. 1094-1098. 231) J.M. Park, K.R. Lim, E.S. Park, S. Hong, K.H. Park, J. Eckert, D.H. Kim, Internal structural evolution and enhanced tensile plasticity of Ti-based bulk metallic glass and composite via cold rolling, Journal of Alloys and Compounds 615 (2014) Nr. S1, S. S113-S117. 232) G. Parzych, D. Mikhailova, S. Oswald, C. Taeschner, M. Ritschel, A. Leonhardt, J. Eckert, H. Ehrenberg, Improved electrochemical performance of Cu3B2O6-based conversion model electrodes by composite formation with different carbon additives, Journal of The Electrochemical Society 161 (2014), S. A1224-A1230. 233) A.K. Patra, F. Fleischhauer, S. Oswald, L. Schultz, V. Neu, Coercivity mechanism in hard magnetic SmCo5/PrCo5 bilayers, Journal of Physics D: Applied Physics 47 (2014), S. 215001/1-8. 234) R. Patra, S. Ghosh, E. Sheremet, M. Jha, R.D. Rodriguez, D. Lehmann, A.K. Ganguli, O.D. Gordan, H. Schmidt, S. Schulze, D.R.T. Zahn, O.G. Schmidt, Enhanced field emission from cerium hexaboride coated multiwalled carbon nanotube composite films: A potential material for next generation electron sources, Journal of Applied Physics 115 (2014), S. 94302/1-7. 92 Publications 2014

235) R. Patra, S. Ghosh, E. Sheremet, M. Jha, R.D. Rodriguez, D. Lehmann, A.K. Ganguli, H. Schmidt, S. Schulze, M. Hietschold, D.R.T. Zahn, O.G. Schmidt, Enhanced field emission from lanthanum hexaboride coated multiwalled carbon nanotubes: Correlation with physical properties, Journal of Applied Physics 116 (2014), S. 164309/1-7. 236) S. Pauly, K. Kosiba, P. Gargarella, B. Escher, K.K. Song, G. Wang, U. Kuehn, J. Eckert, Microstructural evolution and mechanical behaviour of metastable Cu-Zr-Co alloys, Journal of Material Science and Technologie 30 (2014) Nr. 6, S. 584-589. 237) O. Perevertov, R. Schaefer, Influence of applied tensile stress on the hysteresis curve and magnetic domain structure of grain- oriented Fe-3%Si steel, Journal of Physics D: Applied Physics 47 (2014), S. 185001/1-10. 238) O. Perevertov, R. Schaefer, O. Stupakov, 3-D branching of magnetic domains on compressed Si-Fe steel with goss texture, IEEE Transactions on Magnetics 50 (2014) Nr. 11, S. 2007804/1-4. 239) T. Pezeril, C. Klieber, V. Shalagatskyi, G. Vaudel, V. Temnov, O.G. Schmidt, D. Makarov, Femtosecond imaging of nonlinear acoustics in gold, Optics Express (2014), S. 4590-4598. 240) M. Pfeiffer, K. Lindfors, H. Zhang, B. Fenk, F. Phillipp, P. Atkinson, A. Rastelli, O.G. Schmidt, H. Giessen, M. Lippitz, Eleven nanometer alignment precision of a plasmonic nanoantenna with a self-assembled GaAs quantum dot, Nano Letters 14 (2014), S. 197-201. 241) P. Philipp, L. Bischoff, U. Treske, B. Schmidt, J. Fiedler, R. Huebner, F. Klein, A. Koitzsch, T. Muehl, The origin of conductivity in ion-irradiated diamond-like carbon - Phase transformation and atomic ordering, Carbon 80 (2014), S. 677-690. 242) R. Pinedo, I. Ruiz de Larramendi, V.O. Khavrus, D. Jimenez de Aberasturi, J.I. Ruiz de Larramendi, M. Ritscheld, A. Leonhardt, T. Rojo, Microstructural improvements of the gradient composite material Pr0.6Sr0.4Fe0.8Co0.2O3/ Ce0.8Sm0.2O1.9 by employing vertically aligned carbon nanotubes, International Journal of Hydrogen Energy 39 (2014), S. 4074-4080. 243) K. Pinkert, M. Oschatz, L. Borchardt, M. Klose, M. Zier, W. Nickel, L. Giebeler, S. Oswald, S. Kaskel, J. Eckert, Role of surface functional groups in ordered mesoporous carbide- derived carbon/ionic liquid electrolyte double-layer capacitor interfaces, Applied Materials and Interfaces 6 (2014), S. 2922-2928. 244) W. Piyawit, W.Z. Xu, S.N. Mathaudhua, J. Freudenberger, J.M. Rigsbee, Y.T. Zhu, Nucleation and growth mechanism of Ag precipitates in a CuAgZr alloy, Materials Science and Engineering A 610 (2014), S. 85-90. 245) A. Plotnikov, J. Pfeifer, S. Richter, H. Kipphardt, V. Hoffmann, Determination of major nonmetallic impurities in magnesium by glow discharge mass spectrometry with a fast flow source using sintered and pressed powder samples, Analytical and Bioanalytical Chemistry 406 (2014), S. 7463-7471. 246) D. Pohl, U. Wiesenhuetter, E. Mohn, L. Schultz, B. Rellinghaus, Near-surface strain in icosahedra of binary metallic alloys: Segregational versus intrinsic effects, Nano Letters 14 (2014), S. 1776-1784. 247) G. Pollefeyt, S. Clerick, P. Vermeir, J. Feys, R. Huehne, P. Lommens, I. Van Driessche, Ink-jet printing of SrTiO3 buffer layers from aqueous solutions, Superconductor Science and Technology 27 (2014) Nr. 9, S. 95007/1-9. 248) A.A. Popov, C. Kaestner, M. Krause, L. Dunsch, Carbon cage vibrations of M-at- C82 and M2-at- C2 n (M = La, Ce; 2n?=?72, 78, 80): The role of the metal atoms, Fullerenes, Nanotubes and Carbon Nanostructures 22 (2014) Nr. 1-3, S. 202-214. 249) K.G. Prashanth, R. Damodaram, S. Scudino, Z. Wang, K. Prasad Rao, J. Eckert, Friction welding of Al-12Si parts produced by selective laser melting, Materials and Design 57 (2014), S. 632-637. 250) K.G. Prashanth, B. Debalina, Z. Wang, P.F. Gostin, A. Gebert, M. Calin, U. Kuehn, M. Kamaraj, S. Scudino, J. Eckert, Tribological and corrosion properties of Al-12Si produced by selective laser melting, Journal of Materials Research 29 (2014) Nr. 17, S. 2044-2054. 251) K.G. Prashanth, S. Scudino, H.J. Klauss, K.B. Surreddi, L. Loeber, Z. Wang, A.K. Chaubey, U. Kuehn, J. Eckert, Microstructure and mechanical properties of Al-12Si produced by selective laser melting: Effect of heat treatment, Materials Science and Engineering A 590 (2014), S. 153-160. 252) N. Qureshi, P. Steffens, D. Lamago, Y. Sidis, O. Sobolev, R.A. Ewings, L. Harnagea, S. Wurmehl, B. Buechner, M. Braden, Fine structure of the incommensurate antiferromagnetic fluctuations in single-crystalline LiFeAs studied by inelastic neutron scattering, Physical Review B 90 (2014) Nr. 14, S. 144503/1-8. 253) A. Raduta, M. Nicoara, C. Locovei, M. Stoica, J. Eckert, About replacement of Nickel as amorphization element for fabrication of ultra-rapidly solidified Ti-Zr alloys, Solid State Phenomena 216 (2014) Nr. 3, S. 3-10. 254) G.K. Rane, S. Menzel, T. Gemming, J. Eckert, Microstructure, electrical resistivity and stresses in sputter deposited W and Mo films and the influence of the interface on bilayer properties, Thin Solid Films 571 (2014), S. 1-8. 255) L. Reichel, G. Giannopoulos, S. Kauffmann-Weiss, M. Hoffmann, D. Pohl, A. Edstroem, S. Oswald, D. Niarchos, J. Rusz, L. Schultz, S. Faehler, Increased magnetocrystalline anisotropy in epitaxial Fe-Co-C thin films with spontaneous strain, Journal of Applied Physics 116 (2014) Nr. 21, S. 213901/1-5. 256) A. Reifenberger, M. Hempel, P. Vogt, S. Aswartham, M. Abdel-Hafiez, V. Grinenko, S. Wurmehl, S.-L. Drechsler, A. Fleischmann, C. Enss, R. Klingeler, Specific heat of K0.71Na0.29Fe2As2 at very low temperatures, Journal of Low Temperature Physics 175 (2014) Nr. 5-6, S. 755-763. 257) J. Ren, C. Chen, G. Wang, W.-S. Cheung, B. Sun, N. Mattern, S. Siegmund, J. Eckert, Various sizes of sliding event bursts in the plastic flow of metallic glasses based on a spatiotemporal dynamic model, Journal of Applied Physics 116 (2014), S. 33520/1-3. 258) L. Restrepo-Perez, L. Soler, C. Martinez-Cisneros, S. Sanchez, O.G. Schmidt, Biofunctionalized self-propelled micromotors as an alternative on-chip concentrating system, Lab on a Chip 14 (2014), S. 2914-2917. 259) L. Restrepo-Perez, L. Soler, C.S. Martinez-Cisneros, S. Sanchez, O.G. Schmidt, Trapping self-propelled micromotors with microfabricated chevron and heart-shaped chips, Lab on a Chip 14 (2014), S. 1515/1-5. 260) R.O. Rezaev, V.M. Fomin, O.G. Schmidt, Vortex dynamics controlled by pinning centers on Nb superconductor open microtubes, Physica C 497 (2014), S. 1-5. Publications 2014 93

261) E.D.L. Rienks, M. Aerraelae, M. Lindroos, F. Roth, W. Tabis, G. Yu, M. Greven, J. Fink, High-energy anomaly in the Angle-Resolved photoemission spectra of Nd2-xCexCuO4: Evidence for a matrix element effect, Physical Review Letters 113 (2014) Nr. 13, S. 137001/1-5. 262) J. Ringel, K. Erdmann, S. Hampel, K. Kraemer, D. Maier, M. Arlt, D. Kunze, M.P. Wirth, S. Fuessel, Carbon nanofibers and carbon nanotubes sensitize prostate and bladder cancer cells to platinum-based chemotherapeutics, Journal of Biomedical Nanotechnology 10 (2014) Nr. 3, S. 463-477. 263) S. Rittinghausen, A. Hackbarth1, O. Creutzenberg, H. Ernst, U. Heinrich, A. Leonhardt, D. Schaudien, The carcinogenic effect of various multi-walled carbon nanotubes (MWCNTs) after intraperitoneal injection in rats, Particle and Fibre Toxicology 11 (2014), S. 59/1-18. 264) P. Robaschik, P.F. Siles, D. Buelz, P. Richter, M. Monecke, M. Fronk, S. Klyatskaya, D. Grimm, O.G. Schmidt, M. Ruben, D.R.T. Zahn, G. Salvan, Optical properties and electrical transport of thin films of terbium(III) bis(phthalocyanine) on cobalt, Beilstein Journal of Nanotechnology 5 (2014), S. 2070-2078. 265) T. Roch, F. Klein, K. Guenther, A. Roch, T. Muehl, A. Lasagni, Laser interference induced nano-crystallized surface swellings of amorphous carbon for advanced micro tribology, Materials Research Express 1 (2014), S. 35042/1-14. 266) F. Roth, A. Koenig, J. Fink, B. Buechner, M. Knupfer, Electron energy-loss spectroscopy: A versatile tool for the investigations of plasmonic excitations, Journal of Electron Spectroscopy and Related Phenomena 195 (2014), S. 85-95. 267) K. Sakaushi, E. Hosono, G. Nickerl, H. Zhou, S. Kaskel, J. Eckert, Bipolar porous polymeric frameworks for low-cost, high-power, long-life all-organic energy storage devices, Journal of Power Sources 245 (2014), S. 553-556. 268) F. Sannicolo, S. Arnaboldi, T. Benincori, V. Bonometti, R. Cirilli, L. Dunsch, W. Kutner, G. Longhi, P.R. Mussini, M. Panigati, M. Pierini, S. Rizzo, Potential-driven chirality manifestations and impressive enantioselectivity by inherently chiral electroactive organic films, Angewandte Chemie - International Edition 53 (2014), S. 2623-2627. 269) A.E. Sarapulova, B. Bazarov, T. Namsaraeva, S. Dorzhieva, J. Bazarova, V. Grossman, A.A. Bush, I. Antonyshyn, M. Schmidt, A.M.T. Bell, M. Knapp, H. Ehrenberg, J. Eckert, D. Mikhailova, Possible piezoelectric materials CsMZr0.5(MoO4)3 (M = Al, Sc, V, Cr, Fe, Ga, In) and CsCrTi0.5(MoO4)3: Structure and physical properties, The Journal of Physical Chemistry C 118 (2014), S. 1763-1773. 270) S. Scheinert, G. Paasch, Influence of the carrier density in disordered organics with Gaussian density of states on organic field-effect transistors, Journal of Applied Physics 115 (2014) Nr. 4, S. 44507/1-8. 271) T. Schied, H. Ehrenberg, J. Eckert, S. Oswald, M. Hoffmann, F. Scheiba, An O2 transport study in porous materials within the Li-O2 -system, Journal of Power Sources 269 (2014), S. 825-833. 272) R. Schlegel, T. Haenke, D. Baumann, M. Kaiser, P.K. Nag, R. Voigtlaender, D. Lindackers, B. Buechner, C. Hess, Design and properties of a cryogenic dip-stick scanning tunneling microscope with capacitive coarse approach control, Review of Scientific Instruments 85 (2014) Nr. 1, S. 13706/1-9. 273) S. Schmitz, H.-G. Lindenkreuz, W. Loeser, B. Buechner, Liquid phase separation, solidification and phase transformations of Gd-Ti andGd-Ti-Al-Cu alloys, CALPHAD: Computer Coupling of Phase Diagrams and Thermochemistry 44 (2014), S. 21-25. 274) S. Schneider, A. Surrey, D. Pohl, L. Schultz, B. Rellinghaus, Atomic surface diffusion on Pt nanoparticles quantified by high- resolution transmission electron microscopy, Micron 63 (2014), S. 52-56. 275) R. Schoenfelder, F. Aviles, M. Knupfer, J.A. Azamar-Barrios, P.I. Gonzalez-Chi, M.H. Ruemmeli, Influence of architecture on the Raman spectra of acid-treated carbon nanostructures, Journal of Experimental Nanoscience 9 (2014) Nr. 9, S. 931-941. 276) H. Shakur Shahabi, S. Scudino, U. Kuehn, J. Eckert, Metallic glass-steel composite with improved compressive plasticity, Materials and Design 59 (2014), S. 241-245. 277) R. Sharma, C.C. Bof Bufon, D. Grimm, R. Sommer, A. Wollatz, J. Schadewald, D.J. Thurmer, P.F. Siles, M. Bauer, O.G. Schmidt, Large-area rolled-up nanomembrane capacitor arrays for electrostatic energy storage, Advanced Energy Materials 4 (2014) Nr. 9, S. 1301631/1-6. 278) W. Si, I. Moench, C. Yan, J. Deng, S. Li, G. Lin, L. Han, Y. Mei, O.G. Schmidt, A single rolled-up Si tube battery for the study of electrochemical kinetics, electrical conductivity, and structural integrity, Advanced Materials 26 (2014), S. 7973-7978. 279) W. Si, X. Sun, X. Liu, L. Xi, Y. Jia, C. Yan, O.G. Schmidt, High areal capacity, micrometer-scale amorphous Si film anode based on nanostructured Cu foil for Li-ion batteries, Journal of Power Sources 267 (2014), S. 629-634. 280) M. Sieger, J. Haenisch, K. Iida, U. Gaitzsch, C. Rodig, L. Schultz, B. Holzapfel, R. Huehne, Pulsed laser deposition of thick BaHfO3 doped YBa2Cu307-delta films on highly alloyed textured Ni-W tapes, Journal of Physics: Conference Series 507 (2014), S. 22032/1-5. 281) B.W. Sigusch, S. Kranz, S. Klein, A. Voelpel, S. Harazim, S. Sanchez, D.C. Watts, K.D. Jandt, O.G. Schmidt, A. Guellmar, Colonization of Enterococcus faecalis in a newSiO/SiO2-microtube in vitro model system as afunction of tubule diameter, Dental Materials 30 (2014), S. 661-668. 282) P.F. Siles, C.C. Bof Bufon, D. Grimm, A.R. Jalil, C. Mende, F. Lungwitz, G. Salvan, D.R.T. Zahn, H. Lang, O.G. Schmidt, Morphology and local transport characteristics of metalloporphyrin thin films, Organic Electronics 15 (2014) Nr. 7, S. 1432-1439. 283) J. Simmchen, V. Magdanz, S. Sanchez, S. Chokmaviroj, D. Ruiz-Molina, A. Baeza, O.G. Schmidt, Effect of surfactants on the performance of tubular and spherical micromotors - A comparative study, RSC Advances 4 (2014), S. 20334-20340. 284) W. Skrotzki, A. Eschke, J. Romberg, J. Scharnweber, T. Marr, R. Petters, I. Okulov, C.-G. Oertel, J. Freudenberger, U. Kuehn, L. Schultz, J. Eckert, Processing of high strength light-weight metallic composites, Advanced Engineering Materials 16 (2014) Nr. 10, S. 1208-1216. 285) E. Smirnova, S. Smirnov, A. Sotnikov, M. Shevelko, H. Schmidt, M. Weihnacht, High temperature acoustic anomalies in PMN-PSN solid solution, Ferroelectrics 469 (2014) Nr. 1, S. 67-72. 94 Publications 2014

286) E. Smirnova, A. Sotnikov, S. Ktitorov, N. Zaitseva, H. Schmidt, M. Weihnacht, Acoustic evidence of distinctive temperatures in relaxor-multiferroics, Journal of Applied Physics 115 (2014), S. 54101/1-7. 287) E.P. Smirnova, A.V. Sotnikov, N.V. Zaitseva, H. Schmidt, M. Weihnacht, Evolution of phase transitions in SrTiO3-BiFeO3 solid solutions, Physics of the Solid State 56 (2014) Nr. 5, S. 996-1001. 288) K. Snyder, B. Raguz, W. Hoffbauer, R. Glaum, H. Ehrenberg, M. Herklotz, Lithium Copper (I) orthophosphates Li3-xCuxPO4: Synthesis, crystal structures, and electrochemical properties, Zeitschrift fuer anorganische und allgemeine Chemie 640 (2014) Nr. 5, S. 944-951. 289) A. Sobolkina, V. Mechtcherine, C. Bellmann, V. Khavrus, S. Oswald, S. Hampel, A. Leonhardt, Surface properties of CNTs and their interaction with silica, Journal of Colloid and Interface Science 413 (2014), S. 43-53. 290) I.V. Soldatov, N. Panarina, C. Hess, L. Schultz, R. Schaefer, Thermoelectric effects and magnetic anisotropy of Ga1-xMnxAs thin films, Physical Review B 90 (2014) Nr. 10, S. 104423/1-9. 291) E. Song, W. Si, R. Cao, P. Feng, I. Moench, G. Huang, Z. Di, O.G. Schmidt, Y. Mei, Schottky contact on ultra-thin silicon nanomembranes under light illumination, Nanotechnology 25 (2014) Nr. 48, S. 485201/1-7. 292) F. Steckel, S. Rodan, R. Hermann, C.G.F. Blum, S. Wurmehl, B. Buechner, C. Hess, Spin density wave order and fluctuations in Mn3Si : A transport study, Physical Review B 90 (2014) Nr. 13, S. 134411/1-7. 293) E. Stilp, A. Suter, T. Prokscha, Z. Salman, E. Morenzoni, H. Keller, P. Pahlke, R. Huehne, C. Bernhard, R. Liang, W.N. Hardy, D.A. Bonn, J.C. Baglo, R.F. Kiefl, Controlling the near-surface superfluid density in underdoped YBa2Cu3O61x by photo-illumination, Scientific Reports 4 (2014), S. 6250/1-6. 294) M. Stoica, S. Scudino, J. Bednarcik, I. Kaban, J. Eckert, FeCoSiBNbCu bulk metallic glass with large compressive deformability studied by time-resolved synchrotron X-ray diffraction, Journal of Applied Physics 115 (2014) Nr. 5, S. 53520/1-9. 295) O.A. Stonkus, L.S. Kibis, O.Y. Podyacheva, E.M. Slavinskaya, V.I. Zaikovskii, A.H. Hassan, S. Hampel, A. Leonhardt, Z.R. Ismagilov, A.S. Noskov, A.I. Boronin, Palladium nanoparticles supported on nitrogen-doped carbon nanofibers: Synthesis, microstructure, catalytic properties, and self-sustained oscillation phenomena in carbon monoxide oxidation, ChemCatChem 6 (2014) Nr. 7, S. 2115-2128. 296) R. Streubel, L. Han, F. Kronast, A.A. Uenal, O.G. Schmidt, D. Makarov, Imaging of buried 3D magnetic rolled-up nanomembranes, Nano Letters 14 (2014), S. 3981-3986. 297) R. Streubel, J. Lee, D. Makarov, M.-Y. Im, D. Karnaushenko, L. Han, R. Schaefer, P. Fischer, S.-K. Kim, O.G. Schmidt, Magnetic microstructure of rolled-up single-layer ferromagnetic nanomembranes, Advanced Materials 26 (2014), S. 316-323. 298) V. Stroganov, S. Zakharchenko, E. Sperling, A.K. Meyer, O.G. Schmidt, L. Ionov, Biodegradable self-folding polymer films with controlled thermo-triggered folding, Advanced Functional Materials 24 (2014), S. 4357-4363. 299) R. Sueptitz, K. Tschulik, M. Uhlemann, J. Eckert, A. Gebert, Retarding the corrosion of iron by inhomogeneous magnetic fields, Materials and Corrosion 65 (2014) Nr. 8, S. 803-808. 300) X. Sun, W. Si, X. Liu, J. Deng, L. Xi, L. Liu, C. Yan, O.G. Schmidt, Multifunctional Ni/NiO hybrid nanomembranes as anode materials for high-rate Li-ion batteries, Nano Energy 9 (2014), S. 168-175. 301) X. Sun, C. Yan, Y. Chen, W. Si, J. Deng, S. Oswald, L. Liu, O.G. Schmidt, Three-dimensionally “Curved” NiO nanomembranes as ultrahigh rate capability anodes for Li-Ion batteries with long cycle lifetimes, Advanced Energy Materials 4 (2014) Nr. 4, S. 1300912/1-6. 302) A. Svalov, L. Lokamani, R. Schaefer, V. Vaskovskiy, G. Kurlyandskaya, Magnetization processes and magnetic domain structure in weakly coupled GdCo/Si/Co trilayers, Journal of Alloys and Compounds 615 (2014), S. S366-S370. 303) A.L. Svitova, K.B. Ghiassi, C. Schlesier, K. Junghans, Y. Zhang, M.M. Olmstead, A.L. Balch, L. Dunsch, A.A. Popov, Endohedral fullerene with m3-carbido ligand and titanium-carbon double bond stabilized inside a carbon cage, nature communications 5 (2014), S. 3568/1-8. 304) A.L. Svitova, Y. Krupskaya, N. Samoylova, R. Kraus, J. Geck, L. Dunsch, A.A. Popov, Magnetic moments and exchange coupling in nitride clusterfullerenes GdxSc3–xN-at- C80 (x = 1–3), Dalton Transactions 43 (2014), S. 7387-7390. 305) A.H. Taghvaei, H.S. Shahabi, J. Bednarcik, J. Eckert, Fabrication and characterization of Co40Fe22Ta8-xYxB30 (x=0, 2.5, 4, 6, and 8) metallic glasses with high thermal stability and good soft magnetic properties, Journal of Applied Physics 116 (2014), S. 184904/1-5. 306) A.H. Taghvaei, M. Stoica, J. Bednarcik, I. Kaban, H.S. Shahabi, M.S. Khoshkhoo, K. Janghorban, J. Eckert, Influence of ball milling on atomic structure and magnetic properties of Co40Fe22Ta8B30 glassy alloy, Materials Characterization 92 (2014), S. 96-105. 307) A.H. Taghvaei, M. Stoica, I. Kaban, J. Bednarcik, J. Eckert, Thermal and soft magnetic properties of Co40Fe22Ta8B30 glassy particles: In-situ X-ray diffraction and magnetometry studies, Journal of Applied Physics 116 (2014), S. 54904/1-8. 308) A.H. Taghvaei, M. Stoica, K. Song, K. Janghorban, J. Eckert, Crystallization kinetics of Co40Fe22Ta8B30 glassy alloy with high thermal stability and soft magnetic properties, Journal of Alloys and Compounds 605 (2014), S. 199-207. 309) J. Tan, G. Wang, Z.Y. Liu, J. Bednarcik, Y.L. Gao, Q.J. Zhai, N. Mattern, J. Eckert, Correlation between atomic structure evolution and strength in a bulk metallic glass at cryogenic temperature, Scientific Reports 4 (2014), S. 3897/1-7. 310) M. Taut, K. Koepernik, M. Richter, Electronic structure of stacking faults in rhombohedral graphite, Physical Review B 90 (2014) Nr. 8, S. 85312/1-8. 311) I. Tereshina, J. Cwik, E. Tereshina, G. Politova, G. Burkhanov, V. Chzhan, A. Ilyushin, M. Miller, A. Zaleski, K. Nenkov, L. Schultz, Multifunctional phenomena in Rare-Earth intermetallic compounds with a laves phase structure: Giant magnetostriction and magnetocaloric effect, IEEE Transactions on Magnetics 50 (2014) Nr. 11, S. 2504604/1-4. 312) A. Teresiak, M. Uhlemann, J. Thomas, J. Eckert, A. Gebert, Influence of Co and Pd on the formation of nanostructured LaMg2Ni and its hydrogen reactivity, Journal of Alloys and Compounds 582 (2014), S. 647-658. Publications 2014 95

313) F. Thoss, L. Giebeler, K. Weisser, J. Feller, J. Eckert, Preparation and cycling performance of Iron or Iron Oxide containing amorphous Al-Li alloys as electrodes, Inorganics 2 (2014), S. 674-682. 314) U. Treske, N. Heming, M. Knupfer, B. Buechner, A. Koitzsch, E. Di Gennaro, U. Scotti di Uccio, F. Miletto Granozio, S. Krause, Observation of strontium segregation in LaAlO3/SrTiO3 and NdGaO3/SrTiO3 oxide heterostructures by X-ray photoemission spectroscopy, APL Materials 2 (2014), S. 12108/1-8. 315) U. Treske, M.S. Khoshkhoo, F. Roth, M. Knupfer, E.D. Bauer, J.L. Sarrao, B. Buechner, A. Koitzsch, X-ray photoemission study of CeTIn5 (T = Co, Rh, Ir), Journal of Physics: Condensed Matter 26 (2014), S. 205601/1-5. 316) J. Trommer, S. Boettner, S. Li, S. Kiravittaya, M.R. Jorgensen, O.G. Schmidt, Observation of higher order radial modes in atomic layer deposition reinforced rolled-up microtube ring resonators, Optics Letters 39 (2014) Nr. 21, S. 6335-6338. 317) S. Trommler, J. Haenisch, K. Iida, F. Kurth, L. Schultz, B. Holzapfel, R. Huehne, Investigation of the strain-sensitive superconducting transition of BaFe1.8Co0.2As2 thin films utilizing piezoelectric substrates, Journal of Physics: Conference Series 507 (2014) Nr. 1, S. 12049/1-5. 318) R. Trotta, J.S. Wildmann, E. Zallo, O.G. Schmidt, A. Rastelli, Highly entangled photons from hybrid piezoelectric-semiconductor quantum dot devices, Nano Letters 14 (2014) Nr. 6, S. 3439-3444. 319) H. Turnow, H. Wendrock, S. Menzel, T. Gemming, J. Eckert, Synthesis and characterization of amorphous Ni-Zr thin films, Thin Solid Films 561 (2014), S. 48-52. 320) A. Undisz, R. Hanke, K.E. Freiberg, V. Hoffmann, M. Rettenmayr, The effect of heating rate on the surface chemistry of NiTi, Acta Biomaterialia 10 (2014), S. 4919-4923. 321) V. Velasco, D. Pohl, A. Surrey, A. Bonatto-Minella, A. Hernando, P. Crespo, B. Rellinghaus, On the stability of AuFe alloy nanoparticles, Nanotechnology 25 (2014) Nr. 21, S. 215703/1-8. 322) C. Vervacke, C.C. Bof Bufon, D.J. Thurmer, O.G. Schmidt, Three-dimensional chemical sensors based on rolled-up hybrid nanomembranes, RSC Advances 4 (2014), S. 9723-9729. 323) S. Vock, C. Hengst, M. Wolf, K. Tschulik, M. Uhlemann, Z. Sasvari, D. Makarov, O.G. Schmidt, L. Schultz, V. Neu, Magnetic vortex observation in FeCo nanowires by quantitative magnetic force microscopy, Applied Physics Letters 105 (2014), S. 172409/1-5. 324) U. Vogel, T. Gemming, J. Eckert, S. Oswald, Analysis of surface pre-treatment for SAW substrate material (LiNbO3) and deposited thin films of Ta/Ti using ARXPS, Surface and Interface Analysis 46 (2014), S. 1033-1038. 325) H. Wadati, J. Geck, E. Schierle, R. Sutarto, F. He, D.G. Hawthorn, M. Nakamura, M. Kawasaki, Y. Tokura, G.A. Sawatzky, Revealing orbital and magnetic phase transitions in Pr0:5Ca0:5MnO3 epitaxial thin films by resonant soft x-ray scattering, New Journal of Physics 16 (2014) Nr. 3, S. 33006/1-13. 326) G. Wang, S. Pauly, S. Gorantla, N. Mattern, J. Eckert, Plastic flow of a Cu50Zr45Ti5 bulk metallic glass composite, Journal of Material Science and Technologie 30 (2014) Nr. 6, S. 609-615. 327) K. Wang, A. Maljuk, C.G.F. Blum, T. Kolb, C. Jaehne, C. Neef, H.-J. Grafe, L. Giebeler, H. Wadepohl, H.-P. Meyer, S. Wurmehl, R. Klingeler, Growth, characterization, and magnetic properties of a Li(Mn,Ni)PO4 single crystal, Journal of Crystal Growth 386 (2014) Nr. 16, S. 16-21. 328) Z. Wang, P. Li, Y. Chen, J. He, W. Zhang, O.G. Schmidt, Y. Li, Pure thiophene-sulfur doped reduced graphene oxide: synthesis, structure, and electrical properties, Nanoscale 6 (2014), S. 7281-7287. 329) Z. Wang, K.G. Prashanth, S. Scudino, A.K. Chaubey, D.J. Sordelet, W.W. Zhang, Y.Y. Li, J. Eckert, Tensile properties of Al matrix composites reinforced with in situ devitrified Al84Gd6Ni7Co3 glassy particles, Journal of Alloys and Compounds 586 (2014) Nr. Suppl. 1, S. S419-S422. 330) Z. Wang, K.G. Prashanth, S. Scudino, J. He, W.W. Zhang, Y.Y. Li, M. Stoica, G. Vaughan, D.J. Sordelet, J. Eckert, Effect of ball milling on structure and thermal stability of Al84Gd6Ni7Co3 glassy powders, Intermetallics 46 (2014), S. 97-102. 331) Z. Wang, J. Tan, S. Scudino, B.A. Sun, R.T. Qu, J. He, K.G. Prashanth, W.W. Zhang, Y.Y. Li, J. Eckert, Mechanical behavior of Al-based matrix composites reinforced with Mg58Cu28.5Gd11Ag2.5 metallic glasses, Advanced Powder Technology 25 (2014) Nr. 2, S. 635-639. 332) Z. Wang, J. Tan, B.A. Sun, S. Scudino, K.G. Prashanth, W.W. Zhang, Y.Y. Li, J. Eckert, Fabrication and mechanical properties of Al-based metal matrix composites reinforced with Mg65Cu20Zn5Y10 metallic glass particles, Materials Science and Engineering A 600 (2014), S. 53-58. 333) Z. Weiss, E.B.M. Steers, J.C. Pickering, V. Hoffmann, S. Mushtaq, Excitation of higher levels of singly charged copper ions in argon and neon glow discharges, Journal of Analytical Atomic Spectrometry 29 (2014) Nr. 12, S. 2256-2261. 334) R. Westerstroem, J. Dreiser, C. Piamonteze, M. Muntwiler, S. Weyeneth, K. Kraemer, S.-X. Liu, S. Decurtins, A. Popov, S. Yang, L. Dunsch, T. Greber, Tunneling, remanence, and frustration in dysprosium-based endohedral single-molecule magnets, Physical Review B 89 (2014) Nr. 6, S. 60406(R)/ 1-4. 335) G. Wittenburg, G. Lauer, S. Oswald, D. Labudde, C.M. Franz, Nanoscale topographic changes on sterilized glass surfaces affect cell adhesion and spreading, Journal of Biomedical Materials Research Part A 102 A (2014), S. 2755-2766. 336) C. Wolf-Brandstetter, S. Oswald, S. Bierbaum, H.-P. Wiesmann, D. Scharnweber, Influence of pulse ratio on codeposition of copper species with calcium phosphate coatings on titanium by means of electrochemically assisted deposition, Journal of Biomedical Materials Research Part B: Applied Biomaterials 102 B (2014) Nr. 1, S. 160-172. 337) T.G. Woodcock, F. Bittner, T. Mix, K.-H. Mueller, S. Sawatzki, O. Gutfleisch, On the reversible and fully repeatable increase in coercive field of sintered Nd-Fe-B magnets following post sinter annealing, Journal of Magnetism and Magnetic Materials 360 (2014), S. 157-164. 338) T.G. Woodcock, Q.M. Ramasse, G. Hrkac, T. Shoji, M. Yano, A. Kato, O. Gutfleisch, Atomic-scale features of phase boundaries in hot deformed Nd-Fe-Co-B-Ga magnets infiltrated with a Nd-Cu eutectic liquid, Acta Materialia 77 (2014), S. 111-124. 96 Publications 2014

339) S. Wurmehl, J.T. Kohlhepp, NMR spectroscopy on Heusler thin films - A review, SPIN 4 (2014) Nr. 4, S. 1440019/1-8. 340) W. Xi, C.K. Schmidt, S. Sanchez, D.H. Gracias, R.E. Carazo-Salas, S.P. Jackson, O.G. Schmidt, Rolled-up functionalized nanomembranes as three-dimensional cavities for single cell studies, Nano Letters 14 (2014), S. 4197-4204. 341) Y.-K. Xu, Y.-N. Chen, Y.-J. Guo, L. Liu, J. Zhang, W. Loeser, Experimental parameters during optical floating zone crystal growth of rare earth silicides, Rare Metals 33 (2014) Nr. 3, S. 343-347. 342) Y.-K. Xu, W. Loeser, Y.-J. Guo, X.-B. Zhao, L. Liu, Crystal growth of Gd2PdSi3 intermetallic compound, Transactions of Nonferrous Matals Society of China 24 (2014), S. 115-119. 343) D.G. Yakhvarov, A. Petr, V. Kataev, B. Buechner, S. Gomez-Ruiz, E. Hey-Hawkins, S.V. Kvashennikova, Y.S. Ganushevich, V.I. Morozov, O.G. Sinyashin, Synthesis, structure and electrochemical properties of the organonickel complex [NiBr(Mes)(phen)] (Mes ¼ 2,4,6- trimethylphenyl, phen ¼ 1,10-phenanthroline), Journal of Organometallic Chemistry 750 (2014), S. 59-64. 344) L.X. Yang, G. Rohde, T. Rohwer, A. Stange, K. Hanff, C. Sohrt, L. Rettig, R. Cortes, F. Chen, D.L. Feng, T. Wolf, B. Kamble, I. Eremin, T. Popmintchev, M.M. Murnane, H.C. Kapteyn, L. Kipp, J. Fink, M. Bauer, U. Bovensiepen, K. Rossnagel, Ultrafast modulation of the chemical potential in BaFe2As2 by coherent phonons, Physical Review Letters 112 (2014) Nr. 20, S. 207001/1-6. 345) Y. Yerin, S.-L. Drechsler, G. Fuchs, Ginzburg-Landau analysis of the critical temperature and the upper critical field for three-band superconductors, Journal of Low Temperature Physics 173 (2014), S. 247-263. 346) T. You, N. Du, S. Slesazeck, T. Mikolajick, G. Li, D. Buerger, I. Skorupa, H. Stoecker, B. Abendroth, A. Beyer, K. Volz, O.G. Schmidt, H. Schmidt, Bipolar electric-field enhanced trapping and detrapping of mobile donors in BiFeO3 memristors, ACS Applied Materials and Interfaces 6 (2014), S. 19758-19765. 347) T. You, Y. Shuai, W. Luo, N. Du, D. Buerger, I. Skorupa, R. Huebner, S. Henker, C. Mayr, R. Schueffny, T. Mikolajick, O.G. Schmidt, H. Schmidt, Exploiting memristive BiFeO3 bilayer structures for compact sequential logics, Advanced Functional Materials 24 (2014), S. 3357-3365. 348) E. Zallo, R. Trotta, V. Krapek, Y.H. Huo, P. Atkinson, F. Ding, T. Sikola, A. Rastelli, O.G. Schmidt, Strain-induced active tuning of the coherent tunneling in quantum dot molecules, Physical Review B 89 (2014), S. 241303(R)/1-5. 349) F. Zeng, Y. Kuang, N. Zhang, Z. Huang, Y. Pan, Z. Hou, H. Zhou, C. Yan, O.G. Schmidt, Multilayer super-short carbon nanotube/ reduced graphene oxide architecture for enhanced supercapacitor properties, Journal of Power Sources 247 (2014), S. 396-401. 350) L. Zhang, J. Deng, L. Liu, W. Si, S. Oswald, L. Xi, M. Kundu, G. Ma, T. Gemming, S. Baunack, F. Ding, C. Yan, O.G. Schmidt, Hierarchically designed SiOx/ SiOy bilayer nanomembranes as stable anodes for Lithium ion batteries, Advanced Materials 26 (2014), S. 4527-4532. 351) Y. Zhang, A.A. Popov, L. Dunsch, Endohedral metal or a fullerene cage based oxidation? Redox duality of nitride clusterfullerenes CexM3-xN@C78–88 (x = 1, 2; M = Sc and Y) dictated by the encaged metals and the carbon cage size, Nanoscale 6 (2014), S. 1038-1048. 352) J. Zhao, Q. Deng, S.M. Avdoshenkoe, L. Fu, J. Eckert, M.H. Ruemmeli, Direct in situ observations of single Fe atom catalytic processes and anomalous diffusion at graphene edges, in: PNAS, 111, 15641-15646 (2014). 353) J. Zhao, Q. Deng, A. Bachmatiuk, G. Sandeep, A. Popov, J. Eckert, M.H. Ruemmeli, Free-standing single-atom-thick iron membranes suspended in graphene pores, Science 343 (2014), S. 1228-1232. 354) J. Zhao, M. Shaygan, J. Eckert, M. Meyyappan, M.H. Ruemmeli, A growth mechanism for free-standing vertical Graphene, Nano Letters 14 (2014), S. 3064-3071. 355) L.-F. Zhu, M. Friak, A. Udyansky, D. Ma, A. Schlieter, U. Kuehn, J. Eckert, J. Neugebauer, Ab initio based study of finite-temperature structural, elastic and thermodynamic properties of FeTi, Intermetallics 45 (2014), S. 11-17. 356) K. Zhuravleva, M. Boenisch, S. Scudino, M. Calin, L. Schultz, J. Eckert, A. Gebert, Phase transformations in ball-milled Ti-40Nb and Ti-45Nb powders upon quenching from the beta—phase region, Powder Technology 253 (2014), S. 166-171. 357) K. Zhuravleva, R. Mueller, L. Schultz, J. Eckert, A. Gebert, M. Bobeth, G. Cuniberti, Determination of the Young’s modulus of porous beta- type Ti–40Nb by finite element analysis, Materials and Design 64 (2014), S. 1-8. 358) M. Zier, F. Scheiba, S. Oswald, J. Thomas, D. Goers, T. Scherer, M. Klose, H. Ehrenberg, J. Eckert, Lithium dendrite and solid electrolyte interphase investigation using OsO4, Journal of Power Sources 266 (2014), S. 198-207. 359) V. Zolyomi, H. Peterlik, J. Bernardi, M. Bokor, I. Laszlo, J. Koltai, J. Kuerti, M. Knupfer, H. Kuzmany, T. Pichler, F. Simon, Toward synthesis and characterization of unconventional C66 and C68 Fullerenes inside carbon nanotubes, The Journal of Physical Chemistry C 118 (2014), S. 30260-30268. 360) K. Zuzek Rozman, F. Rhein, U. Wolff, V. Neu, Single-vortex magnetization distribution and its reversal behaviour in Co-Pt nanotubes, Acta Materialia 81 (2014), S. 469-475.

Contributions to Conference proceedings and monographs 1) J. Acker, J. Ducke, A. Rietig, T. Mueller, S. Eisert, B. Reichenbach, W. Loeser, Segregation, grain boundary milling, and chemical leaching for the refinement of metallurgical grade silicon for photovoltaic application, in: Silicon for the Chemical and Solar Industry XII, Eds.: H.A. Øye, H. Brekken, H.M. Rong, M. Tangstad, H. Tveit, The Norwegian University of Science and Technology, Trondheim, Norway,177-188 (2014). 2) S.V. Biryukov, H. Schmidt, A. Sotnikov, M. Weihnacht, S. Sakharov, O. Buzanov, CTGS material parameters obtained by versatile SAW measurements, IEEE International Ultrasonics Symposium, in: Proceedings, 882-885 (2014). 3) F. Boerrnert, T. Riedel, H. Mueller, M. Linck, B. Buechner, H. Lichte, In-situ (S)TEM redesigned: Concept and electron-holographic performance, 18th International Microscopy Congress, (2014), in: Proceedings, IT-7-O-1894 (2014). 4) R. Bruenig, A. Winkler, S. Wege, H. Schmidt, SAW technology for microfluidics and considerations about efficiency, 4th European Conference on Microfluidics, Limerick/ Ireland, 10.-12.12.14, in: Proceedings, 20141-20148 (2014). Publications 2014 97

5) A. Darinskii, M. Weihnacht, H. Schmidt, Surface acoustic wave scattering by substrate edges, IEEE International Ultrasonics Symposium, in: Proceedings, 2055-2058 (2014). 6) F. Ding, B. Li, F.M. Peeters, A. Rastelli, V. Zwiller, O.G. Schmidt, Excitons confined in single semiconductor quantum rings: Observation and manipulation of Aharonov-Bohm-type oscillations, in: Physics of quantum rings, Berlin: Springer-Verl., Series: NanoScience and Technology, 299-328 (2014). 7) S. Doerfler, K. Pinkert, A. Meyer, M. Weiser, H. Althues, L. Giebeler, M. Schneider, J. Eckert, A. Michaelis, E. Beyer, S. Kaskel, Highly porous carbon electrodes for energy storage and conversion application, International ECEMP Colloquium 2013, Dresden, 25.-26.10.13, in: ECEMP-European Centre for Emerging Materials and Processes Dresden - Ressourcenschonende Werkstoffe - Technologien - Prozesse, Verl. Wissenschaftliche Scripten, 427 (2014). 8) D. Ernst, M. Melzer, D. Makarov, F. Bahr, W. Hofmann, O.G. Schmidt, T. Zerna, Packaging technologies for (Ultra-)thin sensor applications in active magnetic bearings, 37th International Spring Seminar on Electronics Technology (ISSE), in: Proceedings, 125-129 (2014). 9) V.M. Fomin, Quantum ring: A unique playground for the quantum-mechanical paradigm, in: Physics of quantum rings, Berlin: Springer-Verl., Series: NanoScience and Technology, 1-24 (2014). 10) L. Giebeler, F. Thoss, I. Lindemann, C. Bonatto Minella, B. Boehme, S. Peters, M. Baitinger, J. Grin, J. Eckert, L. Schultz, Solid state hydrogen storage materials and metallic anodes for mobile and stationary applications, International ECEMP Colloquium 2013, Dresden, 25.-26.10.13, in: ECEMP-European Centre for Emerging Materials and Processes Dresden - Ressourcenschonende Werkstoffe - Technologien - Prozesse, Verl. Wissenschaftliche Scripten, 385 (2014). 11) S. Giudicatti, S.M. Marz, S. Boettner, B. Eichler, M.R. Jorgensen, O.G. Schmidt, Rolled-up TiO2 microtubes for photonics applications, in: SPIE Proceedings, Photonic Crystal Materials and Devices XI, 9127, 912706/1- (2014). 12) G. Hrkac, K. Butler, T.G. Woodcock, T. Schrefl, O. Gutfleisch, Impact of different Nd-rich and Cu-doped crystal-phases on the coercivity of Nd-Fe-B grain ensembles, 23nd International Workshop on Rare Earth and Future Permanent Magnets and their Applications, Annapolis/ USA, 17.-21.8.14, in: Proceedings, 279-281 (2014). 13) R. Huehne, S. Trommler, P. Pahlke, L. Schultz, Low temperature performance of Pb(Mg1/3Nb2/3)0.72Ti0.28O3 single crystals mapped by metallic and superconducting thin films, 2014 Joint IEEE International Symposium on the Applications of Ferroelectrics, International Workshop on Acoustic Transduction Materials and Devices, in: IEEE Proceedings, 1-4 (2014). 14) T. Marr, J. Romberg, J. Freudenberger, J. Scharnweber, A. Eschke, C.-G. Oertel, I. Okulov, R. Petters, U. Kuehn, J. Eckert, L. Schultz, W. Skrotzki, Feines Gefuege, fester Werkstoff, International ECEMP Colloquium 2013, Dresden, 25.-26.10.13, in: ECEMP-European Centre for Emerging Materials and Processes Dresden - Ressourcenschonende Werkstoffe - Technologien - Prozesse, Verl. Wissenschaftliche Scripten, 375 (2014). 15) G. Martin, E. Chilla, H. Schmidt, B. Steiner, Second-harmonic suppression in DART-SFIT devices, IEEE International Ultrasonics Symposium, in: Proceedings, 2015-2018 (2014). 16) M. Mietschke, S. Faehler, L. Schultz, R. Huehne, Influence of the deposition geometry on structural and ferroelectric properties of epitaxial PMN-PT films, 2014 Joint IEEE International Symposium on the Applications of Ferroelectrics, International Workshop on Acoustic Transduction Materials and Devices, in: IEEE Proceedings, 1-4 (2014). 17) T. Mix, L. Schultz, T.G. Woodcock, Crystal structure and hard magnetic properties of Mn-Ga compounds, 23nd International Workshop on Rare Earth and Future Permanent Magnets and their Applications, Annapolis/ USA, 17.-21.8.14, in: Proceedings, 259-261 (2014). 18) R. Niemann, A. Diestel, A. Backen, U.K. Roessler, C. Behler, S. Hahn, M.F.-X. Wagner, L. Schultz, S. Faehler, Controlling reversibility of the magneto-structural transition in first-order materials on the micro scale, 6th International Conference on Magnetic Refrigeration at Room Temperature (Thermag VI), Victoria/ Canada, 7.-10.9.14, in: Proceedings, 1623/1-2 (2014). 19) A. Sanchez, V. Magdanz, O.G. Schmidt, S. Misra, Magnetic control of self-propelled microjets under ultrasound image guidance, 5th IEEE RAS and EMBS International Conference on Biomedical Robotics and Biomechatronics (BioRob), Sao Paulo/ Brazil, 12.-15.8.14, in: Proceedings, 169-174 (2014). 20) S. Sanchez, W. Xi, A.A. Solovev, L. Soler, V. Magdanz, O.G. Schmidt, Tubular micro-nanorobots: Smart design for bio-related applications, in: Small-Scale Robotics. From Nano-to-Millimeter-Sized Robotic Systems and Applications. Lecture Notes in Computer Science, Berlin: Springer-Verl., 2014, I. Paprotny, S. Bergbreiter (eds.), 8336, 16-27 (2014). 21) K. Schulz, D. Ernst, S. Menzel, J., Wolter, K.-J. Eckert, Thermosonic Platinum wire bonding on Platinum, 37th International Spring Seminar on Electronics Technology, Advances in Electronic System Integration, Dresden/ Germany, 7.-11.5.14, in: Proceedings, 64-65 (2014). 22) K. Schulz, D. Ernst, S. Menzel, T. Gemming, J. Eckert, K.-J. Wolter, Thermosonic platinum wire bonding on platinum, 37th Interna- tional Spring Seminar on Electronics Technology (ISSE), Dresden/ Germany, 7.-11.5.14, in: Proceedings, 120-124 (2014). 23) A.H. Taghvaei, M. Stoica, K. Janghorban, J. Eckert, Ball milling-induced nanocrystallization of Co40Fe22Ta8B30 metallic glass with high thermal stability and good soft magnetic properties, 5th International Conference on Nanostructures (ICNS5), Institute for Nanoscience and Nanotechnology (INST), Sharif University of Technology, Tehran/ Islamic Republic of Iran, 6.-9.3.14, in: Proceedings (Hrsg. M. Reza Ejtehadi), Part 2, 974 (2014). 24) T.G. Woodcock, Q.M. Ramasse, G. Hrkac, T. Shoji, M. Yano, A. Kato, O. Gutfleisch, Phase boundaries in hot deformed Nd-Fe-Co-B-Ga magnets infiltrated with a Nd-Cu eutectic liquid, 23nd International Workshop on Rare Earth and Future Permanent Magnets and their Applications, Annapolis/ USA, 17.-21.8.14, in: Proceedings, 282-284 (2014). 25) J. Zhao, Q. Deng, S.M. Avdoshenkoe, L. Fu, J. Eckert, M.H. Ruemmeli, Direct in situ observations of single Fe atom catalytic processes and anomalous diffusion at graphene edges, in: PNAS, 111, 15641-15646 (2014). 98 Publications 2014

Invited talks 1) S.-H. Baek, D.V. Efremov, J.M. Ok, J.S. Kim, J. van den Brink, B. Buechner, Orbital-driven nematicity and superconductivity in FeSe: NMR study, Orbital-driven nematicity and Superconductivity in FeSe: NMR study, Trieste/ Italien, 27.-31.10.14 (2014). 2) M. Boenisch, M. Calin, A. Panigrahi, T. Waitz, M. Zehetbauer, A. Helth, A. Gebert, L. Giebeler, J. van Humbeeck, W. Skrotzki, J. Eckert, Displacive and diffusional phase transformations in Ti-Nb alloys, Seminar, Forschungsgruppe Physik funktioneller Materialien, Universitaet Wien, Wien/ Oesterreich, 10.3.14 (2014). 3) F. Boerrnert, A flexible multi-stimuli in-situ (S)TEM: Concept, optical performance, and outlook, Ernst Ruska-Centrum, Forschungszentrum Juelich, 4.11.14 (2014). 4) F. Boerrnert, A dedicated in-situ (S) TEM, Holo Workshop, Dresden, 10.-12.6.14 (2014). 5) S. Borisenko, ARPES of iron-based superconductors, International Workshop on Iron-based Superconductors, Beijing/ China, 4.-8.8.14 (2014). 6) S. Borisenko, ARPES of iron-based superconductors, Multi-Condensates Superconductivity, Erice, Sicily/ Italy, 19.-25.7.14 (2014). 7) S. Borisenko, ARPES of iron-based superconductors, Multi-Condensate Superconductivity and Superfluidity in Solids and Ultracold Gases, Camerino/ Italy, 24.-27.6.14 (2014). 8) S. Borisenko, ARPES of iron-based superconductors, EMN Summer Meeting Energy, Materials and Nanotechnology, Cancun/ Mexico, 9.-12.6.14 (2014). 9) S. Borisenko, Graphene-like electronic structure in one and three dimensions, 2014 EMN Spring Meeting, Las Vegas, NV/ USA, 27.2.-2.3.14 (2014). 10) S. Borisenko, ARPES of iron-based superconductors: recent results and current understanding, 4th International Conference on Superconductivity and Magnetism, Antalya/ Turkey, 27.4.-2.5.14 (2014). 11) S. Borisenko, ARPES of iron-based superconductors: recent results and current understanding, Seminar at ETH Zuerich, Zuerich/ Switzerland, 13.-14.3.14 (2014). 12) B. Buechner, Magnetism and nanoscale electronic properties in transition metal oxides, Doctorate Colloquium, Universita degli Studi di Pavia, Pavia/ Italy, 13.3.14 (2014). 13) B. Buechner, NMR studies of nanoscale electronic order in high temperature superconductors, Superstripes 2014, Erice, Sicily/ Italien, 25.-31.7.14 (2014). 14) B. Buechner, Spin Gaps in doped S=1/2 antiferromagnetic Heisenberg chains, IV. International Conference on Superconductivity and Magnetism (ICSM 2014), Antalya/ Tuerkei, 27.4.-2.5.14 (2014). 15) B. Buechner, Phase diagrams of Fe based superconductors, CIMTEC 2014, 13th International Conference on Modern Materials and Technologies, Montecatini Terme, Tuscany/ Italy, 8.-13.6.14 (2014). 16) B. Buechner, FeSe: a model system for Fe based superconductors, Magnetism, Bad Metals and Superconductivity: Iron Pnictides and Beyond, Santa Barbara/ USA, 2.-8.11.14 (2014). 17) B. Buechner, Low dimensional cuprates with antiferromagnetic chains: Spin gaps, ballistic spinon heat transport, and doping induced spin states, International Symposium Single Crystals: Growth and Physico-Chemical Properties, University of Paris Sud, Paris/ France, 18.12.14 (2014). 18) B. Buechner, Spin Gaps in doped S=1/2 antiferromagnetic Heisenberg chains, Symposium of the SFB/TR 49, Koenigstein bei Frankfurt/ Main, 8.-10.4.14 (2014). 19) M. Calin, Lessons learned from the coordination of an Initial Training Network (Marie Curie-ITN), Informationsveranstaltung „Foerderung der Mobilitaet und Karriereentwicklung von Nachwuchswissenschaftler/Innen: Marie Sklodowska Curie-Massnahmen in Horizon 2020, TU Dresden, 14.1.14 (2014). 20) M. Calin, Novel Ti-based materials for biomedical applications, Colloquim - Materials Science and Engineering Faculty, University „Politehnica“ Bucharest, Bucharest/ Romania, 9.4.14 (2014). 21) M. Calin, M. Boenisch, A. Helth, K. Zhuravleva, N. Zheng, S. Abdi, F.P. Gostin, A. Gebert, J. Eckert, Novel metastable Ti-based structures for orthopedic applications, Internation Conference ROMAT 2014, Bukarest/ Romania, 15.-17.10.14 (2014). 22) M. Calin, N. Zheng, S. Abdi, M. Boenisch, A. Helth, M.D. Baro, F.P. Gostin, A. Gebert, J. Eckert, Design of biocompatible Ti-based amorphous alloys for implant applications, The 15th International Conference of Rapidly Quenched & Metastable Materials (RQ 15 ), Shanghai/ China, 24.-28.8.14 (2014). 23) M. Daghofer, Fractional chern insulators in strongly correlated multiorbital systems, DPG Fruehjahrstagung Kondensierte Materie, Dresden, 3.4.14 (2014). 24) M. Daghofer, Correlations and topology in multi-orbital models, Theorie-Kolloquium, Universitaet Erlangen, 7.1.14 (2014). 25) M. Daghofer, The spin-orbit coupled … antiferromagnet in iridates, Workshop „Quantum Phenomena in Strongly Correlated Electrons“, Krakow/ Poland, 15.-18.6.14 (2014). 26) M. Daghofer, Itinerant multi-orbital models for Pnictide superconductors, Sommerschule „Multi-Condensates Superconductivity“, Erice/ Italy, 19.-25.7.14 (2014). 27) T. Dey, Novel magnetism in Ir-based oxides, Institut für Physik, Universitaet Augsburg, 29.7.14 (2014). 28) F. Ding, Practical quantum hardware based on semiconductor quantum dots, Seminar TU Dresden, Dresden/Germany, 9.9.14 (2014). 29) F. Ding, Quantum photonics engineering with semiconductor quantum dots, Seminar Heriot-Watt University, Edinburgh/ UK, 19.8.14 (2014). 30) J. Eckert, High-strength ultrafine-grained materials with enhanced deformability, 15th International Conference on Rapidly Quenched and Metastable Materials (RQ 15), Shanghai/ PR China, 26.8.14 (2014). 31) J. Eckert, Tailoring structure formation and mechanical properties of nanomaterials, 14th International Symposium on Plasticity and Its Current Applications (Plasticity ‘14), Freeport/ Bahamas, 7.1.14 (2014). Publications 2014 99

32) J. Eckert, Improving the deformability of metallic glasses and composites, 10th International Conference on Bulk Metallic Glasses (BMG X), Shanghai/ PR China, 4.6.14. (2014). 33) J. Eckert, Tailoring structure formation and properties of metastable alloys and composites, Symposium on „Frontiers of Solidification Research“, DLR Koeln, 29.9.14 (2014). 34) J. Eckert, Neue Materialien auf der Basis metastabiler Phasen, Materialwissenschaftliches Kolloqium, Montanuniversitaet Leoben and Erich-Schmid Institut fuer Materialwissenschaft der Oesterreichischen Akademie der Wissenschaften, Leoben/ Oesterreich, 10.6.14 (2014). 35) J. Eckert, Improving the ductility of bulk metallic glasses by mechanical treatment, Global Research Laboratory Korea- Germany Workshop on Bulk Metallic Glasses and Nanostructured Materials, Jeong Seon/ Korea, 22.8.14 (2014). 36) J. Eckert, Neue Materialien auf der Basis metastabiler Phasen- Modernes Legierungsdesign am Beispiel von metallischen Glaesern und nanostrukturierten Kompositen, Technikwissenschaftliche Klasse der Saechsischen Akademie der Wissenschaften zu Leipzig, Leipzig, 10.10.14 (2014). 37) J. Eckert, Ductilization of bulk metallic glasses by mechanical treatment, 5th International Conference on Materials Science and Technologies (RoMat 2014), Bukarest/ Rumaenien, 16.10.14 (2014). 38) J. Eckert, Complex metallic materials with hierarchical hybrid structures: Tailoring metastable phases for engineering applications, Materials Science and Engineering Congress (MSE 2014), Darmstadt, 25.9.14 (2014). 39) S. Faehler, Multifunktionale Materialien: Von den physikalischen Grundlagen zu neuartigen Sensoranwendungen, TU Chemnitz, 14.4.14 (2014). 40) S. Faehler, Origin of hysteresis in multicaloric materials, THERMAG VI, Victoray, BC/ Canada, 7.-10.9.14 (2014). 41) S. Faehler, Modulated martensite: A scale bridging Lego game for crystallographers and physicists, DPG Fruehjahrstagung, Dresden, 30.3.-4.4.14 (2014). 42) S. Faehler, Multifunctional magnetic materials, TU Chemnitz, 16.12.14 (2014). 43) J. Fink, Untersuchungen zum Mechanismus von konventioneller und unkonventioneller Supraleitung durch winkelaufgeloester Photoemissionsspektroskopie, Kolloquiumsvortrag, Universitaet Kiel, 21.1.14 (2014). 44) J. Fink, ARPES experiments on conventional and unconventional superconductors, SpecNovMat Workshop SLS, Passugg-Araschgen/ Schweiz, 27.2.-3.3.14 (2014). 45) V.M. Fomin, Propulsion mechanism of catalytic jet engines, International Workshop on Micro- and Nanomachines, Hannover/ Germany, 2.-5.7.14 (2014). 46) V.M. Fomin, Impact of topology on physical properties of quantum rings, Invited Topical Talk, DPG-Fruehjahrstagung, Spring Meeting of the German Physical Society, Dresden/ Germany, 31.3.14 (2014). 47) V.M. Fomin, Vortex dynamics in rolled-up superconductor nanostructures, International Conference on Problems of Strongly Correlated and Interacting Systems, Saint-Petersburg/ Russia, 28.-31.5.14 (2014). 48) V.M. Fomin, Effects of topology in physical properties of quantum rings, Institutsseminar, Paul-Drude-Institut fuer Festkoerperelektronik, Berlin/ Germany, 28.4.14 (2014). 49) V.M. Fomin, Topological effects in physical properties of quantum rings, Seminar, Department of Electrical Engineering, University of California, Riverside, California/ USA, 13.3.14 (2014). 50) V.M. Fomin, Dynamics of superconducting vortices in Nb open microtubes, 7th International Conference on Materials Science and Condensed Matter Physics, Chisinau/ Republic of Moldova, 16.-19.9.14 (2014). 51) V.M. Fomin, Theoretical modeling of electronic and optical properties of nanostructures: From the non-adiabaticity of semiconductor nanocrystals to the geometric and topological effects in quantum rings, 3rd International Symposium on Disperse Systems for Electronic Applications, Erlangen/ Germany, 11.-12.9.14 (2014). 52) V.M. Fomin, Topological effects in quantum rings, Seminar, Institute of Semiconductor Physics Siberian Branch of the Russian Academy of Sciences, Novosibirsk/ Russia, 10.10.14 (2014). 53) V.M. Fomin, Quantum rings: A unique playground for topological effects from doubly connectedness to one sidedness, EMN Spring Meeting, Las Vegas, Nevada/ USA, 27.2.-2.3.14 (2014). 54) J. Freudenberger, A. Kauffmann, S. Yin, F. Bittner, D. Seifert, H. Klauss, V. Klemm, W. Schillinger, L. Schultz, Hochfeste Leitermaterialien auf Kupfer-Basis, 5. Dresdener Werkstoffsymposium, Dresden, 8.-9.12.14 (2014). 55) J. Freudenberger, A. Kauffmann, S. Yin, F. Bittner, D. Seifert, H. Klauss, V. Klemm, W. Schillinger, L. Schultz, Hochfeste Kupferleiter, DGM Fachausschuss Werkstoffe der Energietechnik, Dresden, 18.-19.3.14 (2014). 56) A. Gebert, New Ti-based alloys for implant applications, Werkstoffkolloquium Universitaet Erlangen-Nuernberg, Erlangen, 15.4.14 (2014). 57) A. Gebert, A. Helth, K. Zhuravleva, S. Abdi, P.F. Gostin, M. Calin, U. Hempel, R. Medda, E.A. Cavalcanti-Adam, J. Eckert, Tailoring the surfaces of metastable Ti-based alloys at the nanoscale for biomedical applications, 5th International Conference on Materials Science and Technology, RoMat 2014, Bucharest/ Romania, 15.-17.10.14 (2014). 58) A. Gebert, A. Helth, K. Zhuravleva, M. Boenisch, P.F. Gostin, S. Oswald, M. Calin, J. Eckert, New Ti-Nb-based alloys for implant applications, Indo-German Workshop: Strategies for Improved Bone Replacement Materials and Orthopeadic Implants- Design- Manufactoring- Technologies, TU Dresden, Universitaetsklinikum Carl Gustav Carus, Dresden, 19.-21.2.14 (2014). 59) J. Geck, Collective phenomena in strongly interacting electron systems, Kolloquium, Goettingen, 20.5.14 (2014). 60) J. Geck, Charge density wave order in 1T-TaS2 and its relation to superconductivity, Superstripes Konferenz 2014, Erice/ Italien, 19.-25.7.14 (2014). 61) J. Geck, Emergent phenomena in complex electron systems, Eingeladener Vortrag, Universitaet Heidelberg, 14.1.14 (2014). 62) J. Geck, Resonant x-ray spectroscopies in today’s materials research, Kolloquium, Salzburg/ Oesterreich, 22.5.14 (2014). 100 Publications 2014

63) T. Gustmann, 3D laser beam melting at IFW Dresden, Gruppentreffen mit der Gruppe: Selektives Laserstrahlschmelzen, des SFB 814: Additive Fertigung (FAU Erlangen-Nuernberg), Erlangen, 3.12.14 (2014). 64) J. Haenisch, K. Iida, F. Kurth, S. Trommler, E. Reich, V. Grinenko, B. Holzapfel, L. Schultz, C. Tarantini, J. Jaroszynski, T. Foerster, High field transport properties of superconducting Ba(Fe1-xCox)2As2 thin films, EMFL User Meeting, HZDR, Dresden, 19.6.14 (2014). 65) W. Haessler, Supraleitung - nur ein interessantes physikalisches Phaenomen oder auch Basis sinnvoller Anwendungen?, Vortrag am Tag der Wissenschaften am BSZ Radebeul, Radebeul, 18.6.14 (2014). 66) V. Hoffmann, Advances in glow discharge spectrochemistry, 2014 Winter Conference on Plasma Spectrochemistry, Amelia Island, Florida/ USA, 6.-11.1.14 (2014). 67) R. Huehne, Highly textured templates for the growth of superconducting thin films, 17th International Conference on Textures of Materials (ICOTOM), Dresden, 24.-29.8.14 (2014). 68) Y.H. Huo, Molecular beam epitaxy and its application in growing novel quantum structures, Seminar, East China Research Institute of Electronic Engineering, Hefei/ China 10.11.14 (2014). 69) Y.H. Huo, Stretching quantum dots from heavy to light, International Conference of Young Researchers on Advanced Materials, Haikou/ China, 24.-29.10.14 (2014). 70) Y.H. Huo, Novel QDs grown in GaAs/AlGaAs system: Fabrication and characterization, Seminar, Hefei Nation Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei/ China, 16.1.14 (2014). 71) Y.H. Huo, Highly symmetric GaAs quantum dots grown on GaAs (001) substrate, Seminar, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou/ China, 13.1.14 (2014). 72) Y.H. Huo, A light-hole exciton in a quantum dot, Seminar, Institute of Semiconductors, Chinese Academy of Sciences, Beijing/ China, 9.1.14 (2014). 73) D. Karnaushenko, Printable magnetic sensors, 41st International IARIGAI Conference Swansea/ United Kingdom, 7.-10.9.14 (2014). 74) V. Kataev, Low-energy spin dynamics of the spin-orbital Mott insulator Sr2IrO4, Moscow International Symposium on Magnetism MISM-2014, Moscow/ Russia, 29.6.-3.7.14 (2014). 75) V. Kataev, Probing the spin dynamics in novel Iridium oxides by sub-THz ESR, Asia-Pacific EPR/ESR Symposium, Nara/ Japan, 12.-16.11.14 (2014). 76) V. Kataev, Broad-band high-frequency ESR spectroscopy of strongly correlated quantum magnets, 9th Meeting of the European Federation of EPR, EF-EPR2014, Marseille/ Frankreich, 7.-11.9.14 (2014). 77) V. Kataev, Interplay of site disorder and magnetic frustration in the quantum spin magnet CoAl2O4, Seminar at the Molecuar Photoscience Research Center, Kobe University, University of Kobe, Kobe/ Japan, 4.11.14 (2014). 78) V. Kataev, Order-by-disorder in the frustrated quantum spin magnet COAl204, International Conference „Modern Development of Magnetic Resonance“ 2014, Kazan/ Russland, 23.-27.9.14 (2014). 79) V. Kataev, Tunable sub-THz ESR spectroscopy on the spin-orbital Mott insulator Sr2IrO4, International Conference on Superconductivity and Magnetism- ICSM2014, Antalya/ Tuerkei, 27.4.-2.5.14 (2014). 80) V. Kataev, High field ESR spectroscopy on correlated magnetic oxides, Condensed Matter Physics Seminar, KIP, Heidelberg University, Heidelberg/ Germany, 16.5.14 (2014). 81) M. Knupfer, Interfaces of archetype magnetic molecules: from interface dipoles to charge and spin transfer, Fruehjahrstagung der DPG, Dresden 2014, Dresden, 31.3.-4.4.14 (2014). 82) K. Leistner, Control of magnetism in nanostructured materials by structure, microstructure and electric field, Sonderkolloquium, Institut fuer Materialphysik, Westfaelische Wilhelms-Universitaet Muenster, Muenster, 6.11.14 (2014). 83) K. Leistner, Magnetism: A playground for material scientists and electrochemists, Materialphysikalisches Kolloquium, Institut fuer Materialphysik, Westfaelische Wilhelms-Universitaet Muenster, Muenster, 21.7.14 (2014). 84) V. Magdanz, Development of a sperm flagella driven micro-bio-robot, 3rd World Congress on Reproduction, Oxidative Stress and Antioxidants, Paris/ France, 22.-23.5.14 (2014). 85) D. Makarov, Flexible and printable magnetic field sensors, INNOMAG Mitgliederversammlung Fraunhofer-Institut ICT-IMM, Mainz/ Germany, 31.10.14 (2014). 86) D. Makarov, Magnetic nanomembranes, Physikkolloquium, Johannes Kepler Universitaet Linz, Linz/ Austria, 5.6.14 (2014). 87) D. Makarov, Shapeable magnetoelectronics, Naturwissenschaftliche Fakultaet, Universitaet Salzburg, Salzburg/ Austria, 2.6.14 (2014). 88) D. Makarov, Curved magnetic nanomembranes, Institut fuer Materialphysik, Westfaelische Wilhelms-Universitaet Muenster, Muenster/ Germany, 20.5.14 (2014). 89) D. Makarov, Magnetic tubular architectures, Seminar, Department of Physics, Universidad Tecnica Federico Santa Maria, Valparaiso/ Chile, 24.3.14 (2014). 90) D. Makarov, Spin-orbit coupling effects in magnetic sandwiches, Seminar, Department of Physics, Universidad Tecnica Federico Santa Maria, Valparaiso/ Chile, 24.3.14 (2014). 91) D. Makarov, Magnetism in curved geometries, Institute of Physics, Johannes Gutenberg-Universitaet Mainz Mainz/ Germany, 29.4.14 (2014). 92) D. Makarov, Magnetism in curved surfaces, Seminar, Department of Physics, Universidad Tecnica Federico Santa Maria, Valparaiso/ Chile, 18.3.14 (2014). 93) D. Makarov, Imperceptible magnetoelectronics, Seminar, Department of Physics, Universidad Tecnica Federico Santa Maria, Valparaiso/ Chile, 26.3.14 (2014). Publications 2014 101

94) D. Makarov, Flexible Hall effect sensors for automotive applications, Seminar, Department of Physics, Universidad Tecnica Federico Santa Maria, Valparaiso/ Chile, 26.3.14 (2014). 95) D. Makarov, Flexible, stretchable and printable magnetic sensorics, Seminar of the DPG, TU Dresden, Dresden/ Germany, 21.1.14 (2014). 96) D. Makarov, 3D magnetic architectures, Workshop on Magnetoplasmonics, Uppsala University Uppsala/ Sweden, 17.-19.2.14 (2014). 97) D. Makarov, Shapeable magnetic sensorics, Edgar Luescher Seminar, Klosters/ Switzerland, 1.-7.02.14 (2014). 98) D. Makarov, V. Lozovski, Local-field effects in magnetoplasmonic nanostructures, Workshop on Magnetoplasmonics, Uppsala University Uppsala/ Sweden, 17.-19.2.14 (2014). 99) M. Melzer, Stretchable magnetoelectronics, Edgar Luescher Seminar, Klosters/ Switzerland, 1.-7.02.14 (2014). 100) M.R. Mueller, S. Menzel, U. Kuenzelmann, I. Petrov, J. Knoch, K. Kallis, Tackling hillocks growth after Aluminum CMP, International Conference on Planarization/CMP Technology (ICPT) 2014, Kobe/ Japan, 19.-21.11.14 (2014). 101) V. Neu, Epitaxial Rare-Earth Cobalt thin films and multilayers: Tuning anisotropies and functionality, Semiar at IMDEA Nanoscience, Madrid/ Spain, 5.11.14 (2014). 102) V. Neu, Principles and possibilities of quantitative magnetic force microscopy, Seminar at the Instituto de Ciencia de Materiales de Madrid, Madrid/ Spain, 4.11.14 (2014). 103) V. Neu, S. Sawatzki, F. Wehrmann, C. Damm, L. Schultz, Exchange coupled SmCo5/Fe (Co) multilayers, Workshop on Rare Earth and Future Permanent Magnets REPM’14, Annapolis/ USA, 17.-21.8.14 (2014). 104) V. Neu, S. Sawatzki, F. Wehrmann, C. Damm, L. Schultz, Exchange coupled SmCo5/Fe(Co) multilayers, Seminar at the Instituto de Magnetismo Aplicado, Madrid/ Spain, 6.11.14 (2014). 105) R. Niemann, J. Baro, J. Kopecek, O. Heczko, J. Romberg, L. Schultz, S. Faehler, E. Vives, L. Manosa, A. Planes, Microstructural origin of avalanches during the martensitic transformation, Avalanches in Functional Materials and Geophysics Workshop, Magdalene College, Cambridge/ UK, 4.-8.12.14 (2014). 106) R. Niemann, S. Kauffmann-Weiss, C. Behler, A. Diestel, A. Backen, U.K. Roessler, H. Seiner, O. Heczko, S. Hahn, M.F.-X. Wagner, L. Schultz, S. Faehler, Martensitic transformation in epitaxial magnetic shape memory films, Seminar of Device Materials Group, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge/ UK, 8.12.14 (2014). 107) R. Pfrengle, Kooperation und Durchlaessigkeit der Bildungssysteme, Beitrag zur Podiumsdiskussion auf der Fachtagung der IHK Dresden, Dresden, 24.11.14 (2014). 108) R. Pfrengle, Impact der Physik: Wissens- und Technologietransfer, Beitrag zur Podiumsdiskussion auf dem 35. Jahrestag der Deutschen Physikalischen Gesellschaft, Bad Honnef, 21.11.14 (2014). 109) R. Pfrengle, K. Backhaus-Nousch, Research in the field of professional and personal development of academic workers, Vorlesung im Rahmen der International Conference on Development and Implementation of Academic Competencies of PhD students of Technical Sciences an der Slovak University of Technology in Bratislava (Akademisches Jahr 2013/2014), Trnava/ Slowakei, 24.4.14 (2014). 110) R. Pfrengle, K. Backhaus-Nousch, Research in the field of professional and personal development, Vorlesung im Rahmen des gemeinsamen International Doctoral Seminar 2014 der University of Zielona Gora und der Slovak University of Technology in Bratislava, Zielona Gora/ Polen, 19.-21.5.14 (2014). 111) D. Pohl, S. Schneider, J. Rusz, B. Rellinghaus, STEM with electron vortex beams - A route toward local EMCD measurements?, Colloqium in Transmission Electron Microscopy, Uppsala/ Schweden, 5.-6.9.14 (2014). 112) D. Pohl, A. Surrey, B. Bieniek, U. Wiesenhuetter, E. Mohn, F. Schaeffel, L. Schultz, B. Rellinghaus, Segregation phenomena in binary nanoparticles studied by aberration-corrected HRTEM, Eingeladener Vortrag - Institutsseminar Strukturphysik TU Dresden, 14.1.14 (2014). 113) B. Rellinghaus, Phase stabilities in alloy nanoparticles, Vortrag im Physikalischen Kolloquium, Universitaet Kassel, Kassel, 12.6.14 (2014). 114) B. Rellinghaus, D. Pohl, A. Surrey, B. Bieniek, L. Schultz, The effect of surfaces and interfaces on the phase stability of nanoscopic alloys, International Conference on Small Science, ICSS 2014, Hong Kong/ China, 8.-11.12.14 (2014). 115) B. Rellinghaus, D. Pohl, A. Surrey, F. Schmidt, S. Wicht, S. Schneider, L. Schultz, Exploring the structure-property relation of metallic nanoparticles at the atomic scale, Institutsseminar, Okinawa Institute of Science and Technology, OIST, Okinawa/ Japan, 5.12.14 (2014). 116) B. Rellinghaus, D. Pohl, A. Surrey, U. Wiesenhuetter, B. Bieniek, L. Schultz, Phase stabilities at small lentgh scales, 5th International Conference on Materials Science and Technology, RoMat 2014, Bucharest/ Romania, 15.-17.10.14 (2014). 117) M. Richter, Organo-metallic complexes with the largest possible magnetic anisotropy, Seminar der FOR 1282, TU Berlin, Berlin, 26.6.14 (2014). 118) R. Schaefer, Energy-related aspects of magnetic microstructure, TMS 2014 Konferenz, San Diego/ USA, 19.2.14 (2014). 119) R. Schaefer, Magneto-optical analysis of magnetic microstructure, Seminar am Int. Lab. of High Magnetic Fields, Wroclaw/ Poland, 30.5.14 (2014). 120) R. Schaefer, Magnetic domains and flux propagation in bulk magnetic material, Verleihung Barkhausenpreis, Dresden, 7.3.14 (2014). 121) R. Schaefer, Magneto-optical analysis of magnetic microstructure, Seminar an University of Electronic Science and Technology, Chengdu/ China, 15.7.14 (2014). 122) R. Schaefer, Analysis of magnetic microstructure, Seminar at the UGC-DAE Consortium for Scientific Research, Indore/ Indien, 31.10.14 (2014). 102 Publications 2014

123) R. Schaefer, Magetische Domaenen, Schulung im Forschungszentrum der Robert Bosch AG, Gerlingen, 11.6.14 (2014). 124) R. Schaefer, Magneto-optical Kerr microscopy, Schulung an Fudan University, Inst. of Physics, Shanghai/ China, 16.-18.6.14 (2014). 125) R. Schaefer, Some insufficiently explored aspects of magnetic microstructure, Workshop „Micromagnetics: Analysis and Applications, Heidelberg, 4.8.14 (2014). 126) R. Schaefer, Magnetic domain analysis by Kerr microscopy, Blockseminar an University of Electronic Science and Technology, Chengdu/ China, 15.-17.7.14 (2014). 127) R. Schaefer, Magneto-optical Kerr microscopy, Kurs am UGC-DA Consortium for Scientific Research, Indore/ Indien, 26.-27.8.14 (2014). 128) R. Schaefer, Magnetic domains and flux propagation in bulk magnetc material, MSE 2014 Konferenz, Ehrenkolloquium Prof. Schultz, Darmstadt/ Germany, 24.9.14 (2014). 129) R. Schaefer, Magnetic domains and flux propagation in electrical steel, Seminar am Ford Research Lab in Dearborn, Dearborn/ USA, 10.10.14 (2014). 130) R. Schaefer, Magnetic measurements, Vorlesung auf IEEE Magnetics Summer School 2015, Rio de Janeiro/ Brazil, 15.8.14 (2014). 131) R. Schaefer, Magneto-optical Kerr microscopy, Seminar am Indian Institute for Science, Inst. of Physics, Bengalore/ Indien, 28.10.14 (2014). 132) R. Schaefer, Magneto-optical Kerr microscopy, Kurs am Oakridge Natioal Laboratory, Oakridge/ USA, 3.10.14 (2014). 133) H. Schloerb, Elektrochemische Abscheidung nanoskaliger Magnete, Kolloquium der Bezirksgruppe Sachsen der Deutschen Gesellschaft für Oberflaechentechnik (DGO), IFW Dresden, 18.6.14 (2014). 134) H. Schloerb, Electrodeposited nanoscaled magnets, Seminarvortrag, Jozef-Stefan-Institut Ljubljana/ Slowenien, 24.10.14 (2014). 135) H. Schloerb, V. Haehnel, C. Konczak, D. Pohl, A. Funk, S. Oswald, C. Damm, L. Schultz, Recent progress on electrodeposition of magnetic iron-based alloy films and nanowires, 226th Meeting of the Electrochemical Society, Cancun/ Mexico, 5.-8.10.14 (2014). 136) F. Schmidt, D. Pohl, L. Schultz, B. Rellinghaus, A TEM study on nanoparticles: segregation, light element detection and surface energy, Eingeladener Vortrag, IMA, Universitaet Madrid, Madrid/ Spanien, 3.-8.11.14 (2014). 137) O.G. Schmidt, Inorganic nanomembranes for paradigm shifting technologies, Seminar, Shanghai Tech University, Shanghai/ China, 14.5.14 (2014). 138) O.G. Schmidt, Inorganic nanomembranes for paradigm shifting technologies, Colloquium, King Abdullah University, Jeddah/ Saudi Arabia, 22.4.14 (2014). 139) O.G. Schmidt, Materialien, Architekturen und Integration von Nanomembranen, Barkhausen-Festkolloquium, Dresden/ Germany, 7.3.14 (2014). 140) O.G. Schmidt, Nanomembrane devices for microfluidic devices, Graduate Summer School on Nanoparticles and Microfluidics in Biosensorics, Bodrum/ Turkey, 1.-7.9.14 (2014). 141) O.G. Schmidt, Inorganic nanomembranes for flexible and ultra-compact device architectures, Seminar, Soochow University, Suzhou City/ China, 12.5.14 (2014). 142) O.G. Schmidt, Inorganic nanomembranes for flexible and ultra-compact microsystem architectures, Seminar, CAS Institute of Microsystem and Information Technology, Shanghai/ China, 9.5.14 (2014). 143) O.G. Schmidt, From microjet engines to sperm driven micro-biorobots, Workshop on Future Challenges in Nanorobotics Hongkong/ China, 1.6.14 (2014). 144) O.G. Schmidt, Inorganic nanomembranes for paradigm shifting technologies, Seminar, Hefei University of Technology Hefei/ China, 4.6.14 (2014). 145) O.G. Schmidt, Selected topics in nanomaterials II, Lecture, Fudan University, Shanghai/ China, 28.10.14 (2014). 146) O.G. Schmidt, Nanophotonics with nanomembranes, Sino-Germany Bilateral Symposium on Nano-Photonics and Nano- Optoelectronics, Changsha/ China, 22.-27.10.14 (2014). 147) O.G. Schmidt, Rolled-up microtube optical ring resonators - from fabrication to sensing, 560. Wilhelm und Else Heraeus-Seminar „Taking Detection to the Limit: Biosensing with optical microcavities“Bad Honnef/ Germany, 14.-18.4.14 (2014). 148) O.G. Schmidt, Selected topics in nanomaterials I, Lecture, Fudan University, Shanghai/ China, 28.10.14 (2014). 149) O.G. Schmidt, Flexible and shapeable nanomembranes for applications in and with fluids, Flow14, University of Twente, Enschede/ The Netherlands, 18.-21.5.14 (2014). 150) O.G. Schmidt, Inorganic and hybrid nanomembranes: From flexible magneto-electronics to micro-biorobotic applications, Seminar, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang/ China, 3.11.14 (2014). 151) O.G. Schmidt, Inorganic nanomembranes: From flexible magneto-electronics to micro-biorobotic applications, Seminar, University of Electronic Science and Technology of China, Chengdu/ China, 30.10.14 (2014). 152) O.G. Schmidt, Tubular microanalytic systems for on- and off- chip applications, International Seminar on Lab on Chip Biosensor Systems, Kusadasi/ Turkey, 7.-11.9.14 (2014). 153) O.G. Schmidt, Electro-elastic quantum photonic devices, The 2nd International Conference on Nanogenerators and Piezotronics Atlanta, Georgia/ USA, 9.-11.6.14 (2014). 154) O.G. Schmidt, Inorganic nanomembranes for paradigm shifting technologies, Seminar, University of Science and Technology China Hefei/ China, 5.6.14 (2014). 155) O.G. Schmidt, From bubble-propelled microjets to flagella-driven spermbots, International Workshop on Micro- and Nanomachines, Hannover/ Germany, 2.-5.7.14 (2014). 156) L. Schultz, Elektrische und magnetische Funktionswerkstoffe fuer energietechnische Anwendungen, Eingeladener Vortrag / 5. Dresdner Werkstoffsymposium 2014, Dresden, 8.-9.12.14 (2014). Publications 2014 103

157) L. Schultz, Vom Schweben auf Magnetfeldern - die wundersame Welt der Supraleitung, Workshop MS 60 - Von Methoden und Simulationen bis Mobilitaet und Supraleitung, TU Chemnitz, 22.4.14 (2014). 158) L. Schultz, High temperature superconductors and their application for levitation, Plenary Talk / METAL 2014, 23rd International Conference on Metallurgy and Materials, Brno/ Czech Republic, 21.-23.5.14 (2014). 159) L. Schultz, O. de Haas, D. Berger, L. Kuehn, A. Berger, T. Espenhahn, Basics of superconducting levitation and its use in the transport system SupraTrans II, Invited Talk / 14th International Symposium on Magnetic Bearings, Linz/ Austria, 11.-14.8.14 (2014). 160) L. Schultz, A. Kirchner, High temperature superconductors for superconducting levitation, Plenary Talk / MSE 2014 - International Conference on Materials Science and Engineering, Darmstadt, 23.-25.9.14 (2014). 161) L. Schultz, A. Kirchner, Interaction of ferromagnetic and superconducting permanent magnets: Superconducting levitation, Physics Colloquium at Johannes Gutenberg University, Mainz, 9.12.14 (2014). 162) L. Schultz, A. Kirchner, Nanostructured high temperature superconductors for superconducting levitation, OZ-14 Ceremonial Lecture/ 7th German-Japanese International Symposium on Nanostructures, Wenden/ Olpe, 2.-4.3.14 (2014). 163) L. Schultz, D. Pohl, U. Wiesenhuetter, A. Surrey, B. Rellinghaus, Phase stabilities at the nanoscale: Segregation tendencies in small particles, 15th International Conference on Rapidly Quenched and Metastable Materials, RQ15, Shanghai/ China, 24.-28.8.14 (2014). 164) L. Schultz, J. Thielsch, Interaction of ferromagnetic and superconducting permanent magnets- Superconducting levitation, Invited Talk / 10th International Conference on the Scientific and Clinical Applications of Magnetic Carriers, Dresden, 10.-14.6.14 (2014). 165) R. Streubel, Towards magnetic x-ray tomography, Seminar, University of California, Santa Cruz/ USA, 14.11.14 (2014). 166) R. Streubel, Imaging 3D spin textures in non-planar architectures, Seminar, University of California, Berkeley/ USA, 12.8.14 (2014). 167) R. Streubel, Controlling topological charges by imprinting non-collinear spin textures, Conference on Magnetism and Magnetic Materials (MMM), Honolulu/ USA, 3.-7.11.14 (2014). 168) J. van den Brink, Quantum chemistry results on magnetic iridates, Workshop Magnetism, Bad Metals and Superconductivity: Iron Pnictides and Beyond, KITP Santa Barbara/ USA, 7.11.14 (2014). 169) J. van den Brink, Resonant Inelastic X-ray scattering on high Tc cuprates, iron pnictides and magnetic iridates, Workshop Magnetism, Bad Metals and Superconductivity: Iron Pnictides and Beyond, KITP Santa Barbara/ USA, 10.10.14 (2014). 170) J. van den Brink, Resonant inelastic X-ray scattering on magnetic iridates compared to quantum chemistry calculations, IXS Workshop at Stanford Institute for Materials and Energy Sciences, Menlo Park/ USA, 23.9.14 (2014). 171) J. van den Brink, The light that resonant inelastic X-ray scattering sheds on spin and orbital excitations, Workshop Quantum Phenomena in Strongly Correlated Electrons, Cracow/ Poland, 16.6.14 (2014). 172) J. van den Brink, Resonant inelastic X-ray scattering on high Tc cuprates and magnetic iridates, Moscow International Symposium on Magnetism, Moscow/ Russia, 1.7.14 (2014). 173) J. van den Brink, Resonant inelastic X-ray scattering on magnetic iridates compared to quantum chemistry calculations, International Workshop on Mott Physics beyond the Heisenberg Model, Oxford/ UK, 17.9.14 (2014). 174) J. van den Brink, Resonant inelastic X-ray scattering on correlated magnets, Beijing International Workshop (II) on Iron-Based Superconductors, Chinese Academy of Sciences, Beijing/ China, 7.8.14 (2014). 175) J. van den Brink, Quantum spin dynamics probed by resonant inelastic X-ray scattering, Workshop on Quantum Spin Dynamics, Dresden/ Germany, 3.9.14 (2014). 176) J. van den Brink, Resonant inelastic X-ray scattering on high Tc cuprates and magnetic iridates, 32nd International Conference on the Physics of Semiconductors, Austin/ USA, 12.8.14 (2014). 177) J. van den Brink, Workshop summary and outlook, International Workshop on Mott Physics beyond the Heisenberg Model, Oxford/ UK, 18.9.14 (2014). 178) J. van den Brink, Resonant inelastic X-ray scattering on elementary excitations, PSI Summer School on Condensed Matter Research, Zugerberg/ Switzerland, 15.8.14 (2014). 179) S. Wicht, V. Neu, B. Rellinghaus, O. Mosendz, V. Mehta, S. Jain, O. Hellwig, D. Weller, Atomic resolution structure-property relation in L10-FePt-based HAMR media, Eingeladener Vortrag, INTERMAG 2014 Dresden, Dresden, 4.-8.5.14 (2014). 180) S. Wicht, V. Neu, L. Schultz, O. Mosendz, V. Mehta, S. Jain, O. Hellwig, D. Weller, B. Rellinghaus, Influence of the interfacial contact on the magnetic performance of granular FePt media, HGST and Western Digital, San Jose/ USA, 5.-10.4.14 (2014). 181) A. Winkler, Microfluidics using surface acoustic waves, Microfluidics Bio Workshop 2014, TU Dresden, Bad Schandau, 10.6.14 (2014). 182) U. Wolff, Magnetic force microscopy - A tool to study qualitatively and quantitatively superconducting and magnetic structures, Seminar, Angstoemlaboratoriet, Department Physics and Astronomy, Uppsala/ Sweden, 11.-13.6.14 (2014). 183) T.G. Woodcock, Multiscale characterisation and modelling of Nd-Fe-B permanent magnets, Invited Talk at the International Laboratory of High Magnetic Fields and Low Temperatures, Polish Academy of Sciences, Wroclaw/ Poland, 3.6.14 (2014). 184) T.G. Woodcock, Multiscale characterisation and modelling of Nd-Fe-B permanent magnets, Materialphysikalisches Kolloquium, Institut fuer Materialphysik, Westfaelische Wilhems-Universitaet Muenster, Muenster, 14.7.14 (2014). 185) T.G. Woodcock, Q.M. Ramasse, G. Hrkac, T. Schrefl, O. Gutfleisch, Microstructure at the atomic scale and coercivity in Nd-Fe-B magnets, INTERMAG 2014, Symposium „Recent Developments in Permanent Magnets“, Dresden, 4.-8.5.14 (2014). 186) E. Zallo, Control of electronic and optical properties of single and double quantum dots via growth and electroelastic fields, Seminar, Cavendish Laboratory, University of Cambridge, Cambridge/ UK, 10.12.14 (2014). 187) E. Zallo, Control of electronic and optical properties of single and double quantum dots via growth and electroelastic fields, Seminar, Paul-Drude-Institut fuer Festkoerperelektronik, Berlin/ Germany, 11.11.14 (2014). 104 Patents

Patents 2014

Issues of Patents

DE 10 2012 201 713 Verfahren für die Positionierung von Mikrostrukturelementen (07.01.2014) (11202) Inventors: Stefan Harazim, Samuel Sanchez, Oliver G. Schmidt DE 10 2012 201 714 Verfahren zur Herstellung von Mkirofluidsystemen (30.01.2014) (11203) Inventors: Stefan Harazim, Samuel Sanchez, Oliver G. Schmidt DE 10 2009 002 605 Unidirektionaler Wandler für akustische Oberflächenwellen (13.02.2014) (10912) Inventors: Günter Martin, Bert Wall JP 2012-506481 Wandler mit natürlicher Unidirektionalität für akustische Oberflächenwellen (20.03.2014) (11006) Inventors: Günter Martin, Manfred Weihnacht, Sergey Biryukov, Alexander Darinski, Bert Wall AT 513 436 Wandler mit natürlicher Unidirektionalität für akustische Oberflächenwellen (15.05.2014) (11006) Inventors: Günter Martin, Manfred Weihnacht, Sergey Biryukov, Alexander Darinski, Bert Wall RU 2522035 Wandler mit natürlicher Unidirektionalität für akustische Oberflächenwellen (15.04.2014) (11006) Inventors: Günter Martin, Manfred Weihnacht, Sergey Biryukov, Alexander Darinski, Bert Wall EP 2399282 Integrierte Schaltkreise enthaltend Isolationsmaterial und dessen Verwendung in (10903) integierten Schaltkreise (09.04.2014) Inventors: Ehrenfried Zschech, Helmut Hermann, Konstantin Zagarodniy, Gotthard Seifert DE 10 2009 021 508 Selbstpassivierende Elektrodensysteme für mikroakustische Bauteile (22.05.2014) (10999) Inventors: Christoph Eggs, Frederik Fabel, Siegfried Menzel, Mario Spindler EP 1922426 Verfahren zur Herstellung und Verwendung von Halbzeug auf Nickelbasis mit (10506) Rekristallisationswürfeltextur (11.06.2014) Inventors: Jörg Eickemeyer, Dietmar Selbmann, Horst Wendrock, Bernhard Holzapfel DE 10 2013 201 977 Verfahren und Vorrichtung zur Präparation von Proben für transmissionselektronenmikroskopische (11225) Untersuchungen (03.07.2014) Inventors: Volker Hoffmann, Vavara Efimova, Jürgen Thomas, Thomas Gemming, Samuel Grasemann, Alexander Horst, Steffen Grundkowski, Ralf Voigtländer, Swen Marke, Michael Analytis US 12/995,618 Bauelement aus einem ferromagnetischen Formgedächtnismaterial und dessen Verwendung (22.07.2014) (10915) Inventors: Sebastian Fähler, Jeffrey McCord, Miheala Buschbeck, Oleg Heczko, Michael Thomas DE 10 2012 205107 Akustisches Oberflächenbauelement (07.08.2014) (11205) Inventors: Günter Martin, Bernd Steiner DE 10 2012 211 013 Verfahren zur Herstellung von wasserfreiem Ammoniumtrivanadat und wasserfreies (11210) Ammoniumtrivanadat (07.08.2014) Inventors: Galina Zakharova, Christine Täschner, Albrecht Leonhardt DE 10 2013 225 940 Verfahren zur Herstellung von massiven Kalibrationsproben für die analytische Spektrometrie (06.10.2014) (11364) Inventors: Volker Hoffmann, Sven Donath, Harald Merker DE 10 2008 001 986 Formkörper aus einem magnesiumhaltigen Verbundwerkstoff und Verfahren zu seiner Herstellung (10722) (30.10.2014) Inventors: Miroslava Sakaliyska, Jürgen Eckert, Kumar Babu Sureddi, Sergio Scudino DE 10 2008 001 987 Formkörper aus einem aluminiumhaltigen Verbundwerkstoff und Verfahren zu seiner Herstellung (10723) (30.10.2014) Inventors: Miroslava Sakaliyska, Jürgen Eckert, Kumar Babu Sureddi, Sergio Scudino EP 11779110.3 Hochfeste, bei Raumtemperatur plastisch verformbare und mechanische Energie absorbierende (11009) Formkörper aus Eisenlegierungen (05.11.2014) Inventors: Uta Kühn, Jürgen Eckert, Uwe Siegel, Julia Kristin Hufenbach, Min Ha Lee DE 10 2014 211 901 Batterieträger (27.11.2014) (11414) Inventors: Markus Herklotz, Jonas Weiß, Lars Giebeler, Michael Knapp DE 10 2010 041 973 Bauelement auf der Basis akustischer Oberflächenwellen (19.12.2014) (11009) Inventors: Günter Martin, Bert Wall Patents 105

Priority Patent Applications

11401 Verfahren zur Herstellung von amorphen metallischen Partikeln (21.03.2014) Inventors: Uta Kühn, Sven Donath, Michael Franke 11402 Verfahren zur Herstellung der Beweglichkeit von immobilen Zellen (31.01.2014) Inventors: Oliver G. Schmidt 11406 Anodenmaterial für Lithium-Ionen-Batterien (01.04.2014) Inventors: Maik Scholz, Rüdiger Klingeler, Marcel Haft, Sabine Wurmehl, Silke Hampel, Franziska Hammerath, Bernd Büchner 11407 Wandler für akustische Oberflächenwellen mit einer natürlichen Vorzugsrichtung bei der Wellenabstrahlung (09.04.2014) Inventors: Günter Martin 11411 Verfahren zur Herstellung von sphärischen Silizium-Kohlenstoff-Nanokompositen, sphärische Silizium-Kohlenstoff-Nanokomposite und deren Verwendung (04.06.2014) Inventors: Tony Jaumann, Lars Giebeler, Jürgen Eckert 11413 Hochfeste, mechanische Energie absorbierende und korrosionsbeständige Formkörper aus Eisenlegierungen und Verfahren zu deren Herstellung (01.09.2014) Inventors: Josephine Zeisig, Julia Kristin Hufenbach, Uta Kühn, Jürgen Eckert 11414 Batterieträger (20.06.2014) Inventors: Markus Herklotz, Jonas Weiß, Lars Giebeler, Michael Knapp 11415 Ultrakompakter Mikrokondensator und Verfahren zu seiner Herstellung (05.11.2014) Inventors: Daniel Grimm, Martin Bauer, Oliver G. Schmidt 11416 Verfahren zur Rückgewinnung von Metallen der Seltenen Erden aus SE-Fe-enthaltendem Material (22.08.2014) Inventors: Martina Moore, Annett Gebert, Mihai Stoica, Wolfgang Löser 11418 Capacitor and Process for producing thereof (26.08.2014) Inventors: Daniel Grimm, Oliver G. Schmidt, Ivoyl Koutsaroff, Shoichiro Suzuki, Koichi Banno 11419 Capacitor and Process for Producing thereof (26.08.2014) Inventors: Daniel Grimm, Oliver G. Schmidt, Shoichiro Suzuki, Akira Ando, Koichi Banno 11420 Verfahren zur Herstellung von teil- oder vollkristallinen, metastabilen Materialien und teil- oder vollkristalline, metastabile Materialien (23.10.2014) Inventors: Simon Pauly, Konrad Kosiba, Uta Kühn, Jürgen Eckert 11424 Verfahren und Vorrichtung zur Ermittlung von Kraftfeldern, Kraftfeldgradienten, Materialeigenschaften oder Massen mit einem System aus gekoppelten, schwingungsfähigen, balkenartigen Komponenten (12.12.2014) Inventors: Christopher Reiche, Thomas Mühl, Julia Körner 11426 Kompakter Kondensator und Verfahren zu seiner Herstellung (13.10.2014) Inventors: Oliver G. Schmidt 11429 Verfahren zur Herstellung eines aufgerollten elektrischen oder elektronischen Bauelementes (24.11.2014) Inventors: Daniel Grimm, Dmitriy Karnaushenko, Martin Bauer, Daniil Karnaushenko, Denys Makarov, Oliver G. Schmidt 11430 Vorrichtung zur Flüssigkeitszerstäubung und Verfahren zu ihrer Herstellung (06.11.2014) Inventors: Andreas Winkler, Stefan Harazim, Jürgen Eckert, Oliver G. Schmidt

Trademarks

31427 SAWLab Saxony (13.10.2014) Lab leaders: Siegfried Menzel, Hagen Schmidt 106 PhD and diploma/master theses

PhD and diploma/master theses

PhD Theses

Mohan Ashwin Low-Dimensional Quantum Magnets: Single Crystal Growth and Heat Transport Studies, TU Dresden Dirk Bombor Transportmessungen an Supraleitenden Eisenpniktiden und Heusler-Verbindungen, TU Dresden Peixuan Chen Thermal transport through SiGe superlattices, TU Chemnitz Ulana Cikalova Bewertung der Materialermüdung anhand des Skalenverhaltens von thermisch und magnetisch induzierten Signalen, TU Dresden Maria Dmitrikapoulou Investigations of Si-based and Heusler nanostructures, TU Dresden Jan Engelmann Spannungsinduzierte Supraleitung in undotierten BaFe2As2-Dünnschichten, TU Dresden Manuela Erbe Chemische Lösungsabscheidung von (Y,Gd)Ba2Cu3O7-δ-Dünnschichten: Untersuchungen zur Eigenschaftsoptimierung, TU Dresden Piter Gargarella Phase formation, thermal stability and mechanical behaviour of TiCu-based alloys, TU Dresden Prashanth Konda Gokuldoss Selective laser melting nof Al-12Si, TU Dresden Veronika Haehnel Elektrochemisch hergestellte Fe-Pd-Schichten und Nanodrähte - Morphologie, Struktur und magnetische Eigenschaften, TU Dresden Abdelwahab H. A. Hamdy Electrical properties of different kinds of multi-walled carbon nanotubes, carbon nanofibres and nanocomposites materials, TU Dresden Junhee Han Phase separation and structure formation in gadolinium based liquid and glassy metallic alloys, TU Dresden Julia Kristin Hufenbach Entwicklung neuer Stahlgusslegierungen für den Werkzeugbau, TU Dresden Alexander Kauffmann Gefügeverfeinerung durch mechanische Zwillingsbildung in Kupfer und Kupfermischkristall- legierungen, TU Dresden Sandra Kauffmann-Weiß Verzerrte Fe-Pd-Schichten und deren magnetische Eigenschaften, TU Dresden Mohsen Samadi Khoshkhoo Nanostructure formation and thermal stability of Cu- and Cu-based alloys, TU Dresden Stefanos Kourtis Topological & conventional order of spinless fermions in 2D lattices, TU Dresden Maria Krautz Wege zur Optimierung magnetokalorischer Fe-basierter Legierungen mit NaZn13-Struktur für die Kühlung bei Raumtemperatur, TU Dresden Lars Kühn Transportsysteme mit supraleitender Magnetlagertechnik unter Verwendung von massiven Hochtemperatursupraleitern im Trag- und Führsystem, TU Dresden Inge Lindemann Synthese und Charakterisierung neuartiger, gemischter Tetrahydridoborate für die Wasserstoff- speicherung, TU Dresden Susi Lindner Charge transfer at phthalocyanine interfaces, TU Dresden Tom Marr Hochumgeformte Leichtmetallverbundwerkstoffe und deren festigkeitsbestimmende Faktoren, TU Dresden Sven Partzsch Magnetoelectric Coupling Mechanisms in YMn2-xFexO5 and NdFe3(BO3)4 Revealed by Resonant X-ray Diffraction, TU Dresden Gregorzc Parzych Transition metal borates as model electrode materials in Li-ion batteries, TU Dresden Katja Pinkert Mesoporöse Kohlenstoffmaterialien und Nanokomposite für die Anwendung in Superkondensatoren, TU Dresden Ummethala Raghunandan Growth and field emission characteristics of MWCNT’s on different substrates, TU Dresden Jan Romberg Feinlagige und feinkristalline Titan/Aluminium-Verbundbleche, TU Dresden Markus Schäpers Exploring the Frustrated Spin-Chain Compound Linarite by NMR and Thermodynamic Investigations, TU Dresden Ronny Schlegel Untersuchung der elektronischen Oberflächeneigenschaften des stöchiometrischen Supraleiters LiFeAs mittels Rastertunnelmikroskopie und –spektroskopie, TU Dresden Jan Trinckauf An ARPES study of correlated electron materials on the verge of cooperative order, TU Dresden Sascha Trommler Einfluss von reversibler epitaktischer Verspannung auf die elektronischen Eigenschaften supraleitender Dünnschichten, TU Dresden PhD and diploma/master theses 107

Henning Turnow Amorphe Metallschichten und ihre Verwendung als Mikroröhren, TU Dresden Raghu Ummethala Growth and field emission characteristics of MWCNTs on different substrates, TU Dresden Jörn Venderbos Integer and Fractional Quantum Hall effects in Lattice Magnets, Universiteit Leiden Céline Vervacke Sensing and Transport Properties of Hybrid Organic/inorganic Devices, TU Chemnitz Silvia Vock Resolving local magnetization structures by quantitative magnetic force microscopy, TU Dresden Zhi Wang High strength Al-Gd-Ni-Co alloys from amorphous precursors, TU Dresden Ksenia Zhuravleva Porous β-type Ti-Nb alloy for biomedical applications, TU Dresden Martin Zier Untersuchungen zum Einfluss von Elektrodenkennwerten auf die Performance kommerzieller graphischer Anoden in Lithium-Ionen-Batterien, TU Dresden

Diploma and Mater Theses

Alexander Funk Neuartige magnetokalorische Komposite: Herstellung, 3D-Struktur und magnetische Charakterisierung, TU Dresden Romy Schmidt Elektrochemische Abscheidung von Hydroxylapatit auf Ti-Nb-Legierungen, TU Dresden Tina Kirsten Thermo-mechanische Behandlung der biomedizinischen Legierung Ti-40Nb zur Verbesserung der mechanischen Eigenschaften, TU Dresden Louise Klodt Nanosheets Prepared by Pre-Sonication Assisted Liquid Exfoliation of Molybdenum Disulfide, TU Dresden Philipp Natzke Microstructural analysis of Al-Cu Spray Deposits using Impulse Atomization, TU Dresden Elisabeth Preuße Synthese, Funktionalisierung und Charakterisierung von Eisenoxidnanopartikeln für biomedizinische Anwendungen, TU Dresden Martin Löbel Verformungsverhalten mechanisch vorbehandelter amorpher Titanlegierungen, TU Dresden Castro Nava Arturo Development of novel radio-chemotherapy approaches using nanohybirds, TU Dresden Herzig Melanie Spektroskopie an organischen Ladungstransfer-Maerialien, TU Bergakademie Freiberg Khomenko Vladislav Nanoskalige Strukturerzeugung durch elektroneninduzierte Graphitisierung in diamantartigen Kohlenstoffschichten, TU Bergakademie Freiberg Kranz Ludwik Transportmessungen an kleinen Eikristallen, TU Dresden Kühne Tim Spin-polarised scanning tunneling microscopy and spectroscopy on ultra-thin iron films, TU Dresden Müller Eric Spektroskopische Untersuchungen an dotierten Picen-Filmen, TU Dresden Nohr Markus Einkristallzucht und Charakterisierung von aromatischen Ladungstranfersalzen, HTW Dresden Prateek Kumar Aharonov-Bohm Oscillations in a long-perimeter Bi2Te3 nanowire, TU Dresden Christian Quandt Entwicklung einer Anlage für magnetunterstütztes Tempern und Kristallisieren, HTW Dresden Till Meißner Konstruktion und Entwicklung eines Kryo-Magnetkraftmikroskops, HTW Dresden Vignesh Mahalingham Fabrication and investigations of vertically stocked quantum dot devices, TU Chemnitz Michael Zopf Coherent strain tunable single photon sources, TU Dresden Hany Abushall Double jet engines, TU Dresden Robert Keil Resonance fluorescence from GaAs/AIGaAs quantum dots, TU Dresden Karsten Rost Optimisation of an electrochemical etching approach for flexible Hall sensorics, TU Dresden Anna Brunner Untersuchungen zur Flussführung in nicht-orientiertem Elektroblech, TU Dresden Christoph Konczak Elektrochemische Präparation und Charakterisierung von FePd-Schichten für Formgedächtnisanwendungen, TU Dresden Dominik Markó Tiefenempfindliche Kerr-Mikroskopie an fehlorientierten FeSi-Oberflächen, TU Dresden Christian Becker Untersuchung der dynamischen Oberflächen- und Volumenmagnetisierung weichmagnetischer Bänder, TU Dresden Stefan Richter Einfluss uniaxialer Spannungen auf die Eigenschaften Fe-basierter Supraleiterschichten, TU Dresden 108 Calls and Awards

Calls and Awards

Calls on Professorships

Dr. Maria Daghofer Univ. Stuttgart Prof. Dr. Jürgen Eckert Montan Univ. Leoben Dr. Jochen Geck Univ. Salzburg

Appointments as Adjunct, Honorary, Deputy and Associated Professorships

Prof. Dr. Jens Freudenberger Bergakademie TU Freiberg (Deputy Professorship)

Awards

Prof. Dr. Manfred Hennecke Bundesverdienstkreuz Erster Klasse Prof. Dr. Oliver G. Schmidt International Dresden Barkhausen Award Prof. Dr. Jürgen Eckert DGM Preis Dr.-Ing. Alexander Kauffmann DGM Nachwuchspreis 2014 Dr.-Ing. Alexander Kauffmann Förderpreis 2014 des Deutschen Kupferinstituts Dr. Saicharan Aswartham DGKK-Nachwuchsforscherpreis 2014 Martin Grönke VDI Nachwuchspreis Josephine Zeisig Poster Award des DGM Nachwuchsforums

IFW Awards

Dr. Alexey Popov IFF Research Award 2014 Dr. Karin Leistner IMW Research Award 2014 Dr. Lars Giebeler IKM Research Award 2014 Dr. Fei Ding IIN Research Award 2014

Dr. Tom Marr Tschirnhaus-Medal of the IFW for excellent PhD theses Dr. Jan Engelmann Tschirnhaus-Medal of the IFW for excellent PhD theses Dr. Jan Trinkauf Tschirnhaus-Medal of the IFW for excellent PhD theses Dr. Inge Lindemann Tschirnhaus-Medal of the IFW for excellent PhD theses Dr. Alexander Kauffmann Tschirnhaus-Medal of the IFW for excellent PhD theses Dr. Lars Kühn Tschirnhaus-Medal of the IFW for excellent PhD theses Dr. Ronny Schlegel Tschirnhaus-Medal of the IFW for excellent PhD theses Dr. Piter Gargarelle Tschirnhaus-Medal of the IFW for excellent PhD theses Dr. Julia Hufenbach Tschirnhaus-Medal of the IFW for excellent PhD theses Scientific conferences and IFW colloquia 109

Scientific conferences and IFW colloquia

Conferences

Feb. 16 – 20, 2014 Symposium “Magnetic Materials for Energy Applications IV” at TMS Annual Meeting 2014 in San Diego, USA Feb. 25 – March 1, 2014 BioTiNet Winter school 2014, Vienna, Austria March 27/28, 2014 Kick-Off Meeting of the SPP 1458 “High Temperature Superconductivity in Iron Pnictides”, 2nd funding period, IFW Dresden March 30 – Apr. 4, 2014 DPG-Frühjahrstagung der Sektion Kondensierte Materie (SKM) Dresden May 4 – 8, 2014 IEEE International Magnetics Conference (Intermag), Dresden May 5, 2014 Symposium “Energy assisted magnetic recording beyond 1TB/in2” at the INTERMAG 2014 conference, Dresden July 17 – 18, 2014 Workshop “NMR, μSR, Mössbauer spectroscopies in the study of Fe-based and other unconventional high-Tc superconductors”, IFW Dresden Sept. 12/13, 2014 Final IRON-SEA meeting, IFW Dresden Nov. 5 – 8, 2014 BioTiNet Final Meeting, Dresden

IFW Colloquium

30.01.2014 Prof. Dr. Rudolf Schäfer, IFW Dresden, IEEE Distinguished Lecturer, Magneto-Optic Analysis of Magnetic Microstructures 27.03.2014 Prof. Dr. Peter Hirschfeld, University of Florida, Department of Physics, Fe-based Superconductors: What have we learned? 24.04.2014 Dr. Jack J.W.A. van Loon, DESC - Dutch Experiment Support Center, Amsterdam, The Human Hypergravity Habitat, H3 - A ground based facility for Space Explorations and General Human Health Research in Ageing and Obesity 15.05.2014 Prof. Dr. J.M.D. Coey Trinity College, Dublin, Ireland, Gas bubbles in electrolysis. How could magnetic fields help? 110 Guests and Scholarships

Guests and Scholarships

Guest scientists (stay of 4 weeks and more)

Name Home Institute Home country Afrassa, Mesfin Asfaw Addis Ababa Univ. Ethiopia Ethopia Dr. Arayanarakool, Rerngchai BIOS, Institute of Nanotechnology Twente Thailand Arshad, Muhammad Shahid Jozef Stefan Institute, Slovenia Pakistan Asgharzadeh Javid, Fatemeh Material and energy research center Karaj Iran Bogdanov, Nikolay NUST MISiS Moscow Russia Dr. Bonatto Minella, Christian Helmholtz-Zentrum Geesthacht Italy Castro Nava, Arturo National Autonomous Univ. of Mexico Mexico Cho, Dai-Ning National Central Univ. Taiwan China Dr. Cirillo, Giuseppe Univ. of Calabria Italy Dr. Daghofer, Maria Univ. Stuttgart Austria Delmonde, Marcelo Univ. of Sao Paulo Brasilia Dr. Dey, Tusharkanti Indian Institute of Technology Bombay India Enachi, Mihai Technical Univ. of Moldova Rep. of Moldova Fedorov, Alexander St. Petersburg State Univ. Russia Prof. Dr. Garifullin, Ilgiz Zavoisky Physical-Technical Inst., Kazan Russia Ghunaim, Rasha Univ. of Jordan Palestina Dr. Grüneis, Alexander Univ. Vienna Austria Guix Noguera, Maria Catalan Institute of Nanotechnology (ICN) Spain Günes, Taylan Yalova Univ. Turkey Guo, Er-Jia MLU Halle-Wittenberg China Gürsul, Mehmet Cukurova Univ. Turkey Dr. Harnagea, Luminita Univ. Paris Romania Hassan, Abdelwahab Hamdy Fayoum University Egypt Egypt Prof. Dr. Hirschfeld, Peter J. Univ. of Florida USA Dr. Jiang, Chongyun Institute of Semiconductors, Bejing China Dr. Jung, Hyoyun Yonsei Univ. South Korea Dr. Jung, Kyubong Univ. of Tokyo South Korea Dr. Kataeva, Olga A.E. Arbuzov Institute, Kazan Russia Khim, Seunghyun Seoul National Univ. South Korea Kim, Jinyoung Univ. of Technology Lulea, Sweden South Korea Dr. Kim, Beom Hyun Pohang Univ. of Science and Technology China Dr. Kim, Hee Dae Univ. of Oxford South Korea Kirsanske, Gabija Univ. of Copenhagen Lithuania Kravchuk, Volodymyr Bogolyubov Inst. for Theoretical Physics Kiev Ukraine Kulesh, Nikita Ural Federal Univ. Yekaterinburg Russia Dr. Kumar, Sanjeev Iiser Mohali Faculty of Physics India Dr. Leksin, Pavel Kazan Physical Technical Institute Russia Levchenko, Evgeny Tomsk Polytechnic Univ. Russia Dr. Liu, Xianghong Nankai Uni China Machata, Peter Slovak Univ. of Technology, Bratislava Slovakia Makharza, Sami A M Al-Quds Univ. Palestina Dr. Mandarino, Angelo Instituto C. Elio Vittorini Italy Dr. Manna, Anamika Jadavpur Univ. India Dr. Manna, Kaustuv Indian Institute of Science India Matczak, Michael Institute of Molecular Physics PAS Poland Medina Sanchez, Mariana Univ. Autonoma de Barcelona Columbia Miao, Jing Edith Cowan Uni. China Mityashkin, Oleg Kazan State Univ. Russia Guests and Scholarships 111

Mohan, Ashwin Tata Institute of fundamental research India Mondin, Giovanni Univ. Padua Italy Dr. Moravkova, Zuzana Institute of Macromolecular Chemistry Czech Rep. Moscoso Londono, Oscar Univ. des Buenos Aires Columbia Prof. Dr. Nicoara, Mircea Politehnica Univ. Timisoara Romania Niyomsoan, Saisamorn Burapha Univ. Thailand Okulov, Ilya Ural State Technical Univ. Ekaterinburg Russia Oliveira, Roberto UFRJ, Rio de Janeiro Brasilia Pal, Santosh Kumar Indian Institute of Technology Delhi India Plotnikova, Ekaterina Prokhorov General Physics Institute Russia Dr. Reja, Sahinur Univ. of Cambridge India Dr. Romhanyi, Judit Eötvös Univ. Budapest Hungary Saei Ghareh Naz, Ehsan Urmia Univ. Iran Salman, Omar Oday Dijlah Uni. Baghdad Irak Dr. Singh, Shiv Jee Univ. Tokio India Dr. Smirnova, Elena A.F. Ioffe Phys.-Techn. Institut Russia Tosa, Dacian Ioan Politehnica Univ. Timisoara Romania Dr. Ummethala, R. Nandan Indian Inst. of Technology Kanpur India Dr. Vavilova, Evgeniia Zavoisky Physical-Technical Inst. Kazan Russia Dr. Vavilova, Evgeniia Zavoisky Physical-Technical Inst. Kazan Russia Venderbos, Jörn Foundation for Fund. Research on Matter Netherlands Xu, Lei FZ Jülich China Yadav, Ravi Indian Inst. of Sc. Education & Research Mohali India Dr. Yakhvarov, Dmitry Inst. of Organic and Physical Chemistry Kazan Russia Prof. Yokoyama, Yoshihiko IMR Thoku Univ. Japan Japan Zhang, Jiaxiang Peking Univ. China Dr. Zhang, Yang The Hong Kong Polytechnic Univ. China

Scholarships

Name Home country Donor Afrassa, Mesfin Asfaw Ethopien Addis Ababa Univ., Ethopien Dr. Zhang, Yang China AvH Foundation Dr. Dassonneville, Bastien France AvH Foundation Dr. Prando, Giacomo Italy AvH Foundation Dr. Jorgensen, Matthew USA AvH Foundation Martins dos Santos, Jonadabe Brasil CAPES Foundation Brasil Neves, Andre Martins Brasil CAPES Foundation Brasil Romero da Silva, Murillo Brasil CAPES Foundation Brasil Miyakoshi, Shohei Japan Chiba University’s SEEDS Foundation Cao, Jing China China Scholarship Council Li, Gonjin China China Scholarship Council Li, Shilong China China Scholarship Council Lu, Xueyi China China Scholarship Council Ma, Pan China China Scholarship Council Pang, Jinbo China China Scholarship Council Shi, Zhi Xiang China China Scholarship Council Sun, Xiaolei China China Scholarship Council Wang, Pei China China Scholarship Council Dr. Wang, Jiao China China Scholarship Council Xi, Lixia China China Scholarship Council Yin, Yin China China Scholarship Council 112 Guests and Scholarships

Yuan, Xueyong China China Scholarship Council Yuan, Feifei China China Scholarship Council Zhang, Long China China Scholarship Council Zhang, Jiaxiang China China Scholarship Council Zhang, Panpan China DAAD Salazar Enriquez, Christian David Columbia DAAD Madian, Mahmoud Egypt DAAD Chakraborty, Abhra India DAAD Chatterjee, Riddhi Pratim India DAAD Harihara Subramonia, Anand India DAAD Kolay, Santa India DAAD Dr. Kumar, Sarvesh India DAAD Prof. Dr. Mukhopadhyay, N. Krishna India DAAD Natarajan, Harshavardhana India DAAD Pal, Santosh Kumar India DAAD Dr. Singh, Shiv Jee India DAAD Shahid, Rub Nawaz Pakistan DAAD Makharza, Sami A M Palestina DAAD Kamashev, Andrei Russia DAAD Gargarella, Piter Spain DAAD Kavetskyy, Taras Ukraine DAAD Loftin, Christian USA DAAD Dr. Krupskaya, Yulia Russia DFG Sander, Jan Germany ECEMP Attar, Hooyar Iran, Islam. Rep. Edith Cowan University, Australia Mangalore, Deepthi Kamath India ERASMUS MUNDUS Vijay Karnad, Gurucharan India ERASMUS MUNDUS Niyomsoan, Saisamorn Thailand ERASMUS MUNDUS Dr. Brehm, Moritz Austria Erwin Schrödinger Scholarship Iakovleva, Margarita Russia Government of Rep. Tatarstan Liu, Bo China Graduiertenkolleg TU Chemnitz Jia, Yandong China Harbin Institute of Technology, China Cetner, Tomasz Polen High Pressure Physics, PAS Takahashi, Yasuhiro Japan Jasso Support Program Dr. Nenkov, Konstantin Germany ML University Halle-Wittenberg Dr. Kim, Beom Hyun China National Research Foundation of Korea Dr. Chang, Ching-Hao China National Science Council, China Surrey, Alexander Germany Reiner Lemoine Foundation Ryu, Wook Ha South Korea Soul National Univ. Guest stays of IFW members at other institutes 113

Guest stays of IFW members at other institutes

Oliver Schmidt 27.10. – 05.11.2014, Shanghai/China – Kooperation Fudan Univ. Micheal Melzer 1.11. – 10.11.2014, Honolulu/Hawaii/USA – MMM Conference Yongheng Huo 28.10. – 08.11.2014 Heifei/China – Cooperation with Univ. of Science and Technology China Denys Makarov 15.03. – 29.03.2014 Valpraíso/Chile – Universidad Technica Frederico Santa Maria Departmento de Física Robert Streubel 10.03. – 26.03.2014 Berkeley/USA – Advanced Light Source Lawrence Berkeley National Laboratory, Measuring time Vladimir Fomin 03.03. – 16.03.2014 Riverside/USA –Research Cooperation UC Riverside Matthew Jorgensen 03.04. – 15.04.2014 Utah/USA – Research Cooperation University of Utah Stefan Hameister 26.09. – 03.10.2014, Saarbrücken, Highlights der Physik, Michael Hering 26.09. – 03.10.2014, Saarbrücken, Highlights der Physik Ivan Soldatov 14.02. – 24.02.2014, Jekaterinburg/Russland, International Winterschool on Physics, Tilo Espenhahn 13.01. – 23.03.2014, Univ.Niigata/Japan, Students‘ exchange Fritz Kurth 01.05. – 11.05.2014, NHMFL, Tallahassee/USA, measurements Tilo Espenhahn 28.09. – 08.11.2014, Rio de Janeiro/Brasilien, PPP Probral, Univ. exchange program Anne Berger 27.09. – 28.11.2014, Rio de Janeiro/Brasilien, PPP Probral, Univ. exchange program Lars Kühn 26.09. – 12.10.2014, Rio de Janeiro/Brasilien, PPP Probral, Univ. exchange program Prof. Rudolf Schäfer 01.10. – 12.10.2014, Oak Ridge National Lab, Detroit/USA, invited talks and lectures Jens Hänisch 13.12. – 20.12.2014, LANL, Los Alamos/USA, measurements Vamshi Mohan Katukuri 03. – 09.01.2014, International Centre for Theoretical Sciences, Bangalore India, Winter school on „Strongly correlated systems From models to materials“ Stefanos Kourtis 19.03. – 22.04.2014, Boston University, Collaboration on three-dimensional topologically ordered states Stefanos Kourtis 23.04. – 06.05.2014, University of Leeds, Great Britain, Studies on Majorana-fermion lattices in three dimensions Ekaterina Plotnikova 05. – 28.08.2014, Ecole de Physic de Houches, Summer School: Topological aspects of condensed matter physics Judit Romhányi 15.09. – 17.10.2014, Budapest University of Technology and Economics, Department of Physics, Scientific collaboration Carmine Ortix 03. – 26.11.2014 University of Utrecht, Collaboration on theory of graphene nanostructures Jeroen van den Brink 26.10. – 20.11.2014 University of California, Santa Barbara, Workshop „Iron pnictides and beyond“ at Kavli-Institute for Theoretical Physics (KITP) and research visit Ekaterina Plotnikova 28.10. – 21.11.2014 University of California, Santa Barbara, Workshop „Iron pnictides and beyond“ at Kavli-Institute for Theoretical Physics (KITP) and research visit Cristina Gonzalez Gago 13.09. – 29.09.2014, University of Oviedo, Spain, training course and GD-ToF-MS measurements Lixia Xi 16.06. – 06.07.2014, Foundry Research Institute Krakau, Poland, DAAD-PPP Lixia Xi 15.11. – 24.12.2014, Foundry Research Institute Krakau, Poland, DAAD-PPP Junhee Han 29.08. – 13.09.2014, Yonsei University Seoul, Korea 114 Guest stays of IFW members at other institutes

Mariana Calin 03.04. – 26.04.2014, Univ. Politehnica Timisoara & Univ. Politehnica Bucuresti, Timisoara/Bukarest Romania, Teaching and Research activities Bönisch Mathias 25.02. – 14.03.2014, Faculty for Physics, Vienna, Austria Bastien Dassonneville 04.08. – 29.08.2014, École de Physic Les Houches, France, Summer School Deng Qingming 08.01.2013 – 10.06.2014, Nagoya Univ. Japan, Research cooperation on the formation mechanism of endohedral metallofullerenes Alexander Fedorov 09.01. – 24.01.2014, Elettra Sincrotrone Trieste, Italy, Measurements Alexander Fedorov 09.03. – 24.03.2014, Bessy Berlin, Measurements Grafe Hans-Joachim 14.03. – 16.05.2014, Univ. of California, Davis, California, USA, Research stay Sirko Kamusella 01.06. – 22.07.2014, Paul Scherrer Institut Villigen, Switzerland, Measurements at SwissMuonSource Wolf Schottenhamel 26.01. – 16.02.2014, Brookhaven National Laboratory, New York, USA, Measurements Yulia Krupskaya 01.07.2013 – 30.06.2015, DPMC University of Geneva, Switzerland Zhonghao Liu 01.10.2013 – 31.08.2014, HZB Berlin at Bessy II, measurements Board of Trustees, Scientific Advisory Board 115

Board of trustees

Jörg Geiger, Saxonian Ministry of Science and Art - Head - Dr. Herbert Zeisel, Federal Ministry of Education and Research Prof. Dr. Gerhard Rödel, TU Dresden Prof. Dr. Konrad Samwer, Univ. Göttingen

Scientific Advisory Board

Prof. Dr. Maria-Roser Valenti, Univ. Frankfurt, Germany - Head - Prof. Dr. Philippe M. Fauchet, Vanderbilt Univ., USA Prof. Dr. Matthias Göken, Univ. Erlangen-Nürnberg, Germany Prof. Dr. Alan Lindsay Greer, Univ. of Cambridge, U.K. Prof. Dr. Rudolf Gross, Walter Meißner Institute Garching, Germany Prof. Dr. Rolf Hellinger, Siemens AG Erlangen, Germany Prof. Dr. Xavier Obradors Berenguer, Univ. Autònoma de Barcelona, Spain Prof. Dr. Roberta Sessoli, Univ. di Firenze, Italy Prof. Dr. Eberhardt Umbach, Karlsruhe Institute of Technology, Germany 116 Research organization of IFW Dresden Date: 01/2015 Institute for Theoretical for Institute (ITF) Physics Solid State Prof. Dr. Jeroen van den Brink Secr.: Grit Rötzer - 400 Numerical Solid State Physics - 380 Manuel Richter Dr. Quantum Chemistry - 360 Liviu Hozoi Dr. Quantum theory of complex nanoarchitectures Carmine OrtixDr. - 1829 - 352 Institute for Institute (IIN) Nanosciences Integrative Prof. h. c. Prof. Dr. G. Schmidt Oliver Secr.: Ulrike Steere Ref.: Anja Schanze - 800 Magnetic Nanomembranes - 810 - 845 ERC-Group “Shapeable Magnetoelectronics” Denys Makarov Dr. Photonics Rolled-up - 648 Matthew Jorgensen Dr. - 1152 Nanonphotonics Integrated Fei Ding Dr. Integration of Material and Living Matter on the Nanoscale Anne-Karen Meyer Dr. - 752 Location Chemnitz - 218 Smart Systems Campus Prof. h. c. Prof. Dr. G. Schmidt Oliver - 800 Johanna Riedel - 198 Institute for Institute MaterialsComplex (IKM) Jürgen Eckert Prof. Dr. - 602 Secr.: Brit Präßler-Wüstling - 217 Micro- and Nanostructures Thomas Gemming Dr. Solidification Processes and - 298 Complex Structures Mihai Stoica Dr. Magnetic and Composites Applications Anja Waske Dr. - 644 Chemistry of Functional Materials Annett GebertDr. - 846 Materials for Energy Applications - 275 Lars Giebeler Dr. Alloy Design and Processing - 652 Uta Kühn Dr. Metallic Glasses and Composites Simon Pauly Dr. - 402 - 451 Institute for Institute Metallic Materials (IMW) Schäfer Rudolf Prof. Dr. (temp.) - 223 Secr.: Fleischer Svea - 102 Magnetism and Superconductivity Schlörb (temp.) Heike Dr. - 230 Metal Physics Jens Freudenberger Dr. - 550 Superconducting Materials Hühne (temp.) Ruben Dr. - 716 Magnetic Microstructures Schäfer Rudolf Prof. Dr. - 223 Metastable and Nanostructured Materials Bernd Rellinghaus Dr. Location Niedersedlitz - 754 Info Center SupraTrans Ludwig Schultz Prof. Dr. - 101 Manja Maluck - 805 Institute for Institute (IFF) Research Solid State Bernd Büchner Prof. Dr. - 808 Secr.: Kerstin Höllerer - 300 Electron spectroscopy and microscopy Martin KnupferProf. Dr. - 544 Synchrotron methods Sergey BorisenkoDr. Synthesis and crystal growth - 566 Sabine Wurmehl Dr. and scanning probe Transport microscopy - 519 ChristianDr. Heß Magnetic properties - 533 Kataev Vladislav Dr. Surface dynamics - 328 Hagen Schmidt Dr. Nanoscale chemistry - 278 Alexey Popov Dr. - 871 Research organization of IFW Dresden organization Research Organization chart of the IFW Dresden Date:12/2014 Safety Officer (SI) M. Sc. KrausAndrej -359 Finance Deparment Human Resources and Disposal Purchase Information and Documentation Facility Management Administrative Division Dipl.-Kffr. -620Friederike Jaeger Ulrike Nitzold Secr.: -621 81 Dipl.-Phil. Martina Schmidt -457 82 Dipl.-Ing.-Ök. Klaus-Dieter Faulian -578 83 Marion Hauptmann -254 (temp.) 84 Dipl.-Bibl. Nadja Röder -366 85 Ing. Effenberg Werner -201 Internal Auditor (IR) (FH) Dipl.-Betriebsw. Stefan Leipnitz -876 Electrical Engineering and Electronics Mechanical Engineering Information Technologies Data Security Officer Data Security Officer Ralph Wagner Dr. tel.: 0351 810 31 50 Research Technology Division Technology Research Dr. Prof. Dirk Lindackers Nicole BüttnerSecr.: 71 -580 -505 Dipl.-Ing. (FH) Karsten Peukert -509 72 Ralf Voigtländer Dr. -121 73 Dr. Zimmermann Herbert -345 Knowledge and Transfer Technology (WTT) Uwe Siegel Dr. -424 Company Medical Officer Dieter Jährig Dr. tel.: 03591 326 630 Project Funding,Project EU-office (FF) Dipl.-Ing. Ök. MB (TU) Benz -770Birgit Institute for Theoretical Solid State Physics Dr. Prof. van den Brink Jeroen Grit Rötzer Secr.: -400 -380 Youth and Trainee Youth Council Representative Wittig Marco -130 Patent Patent Agents Rauschenbach tel.: 0351 475 99 90 Support Staff Public Relation, Media (PR) Langer -234 Carola Dr. Institute for Integrative Nanosciences h. c. Prof. Dr. Prof. Oliver G. Schmidt -800 Ass.: Anja Schanze -845 Ulrike Steere Secr.: -810 Representative Body for Representative Disabled Employees Hartmut Siegel -507Dr. -217 General Meeting Board of Trustees Head: MDgt Jörg Geiger Head: MDgt Jörg Internet www.ifw-dresden.de [email protected] Brit Präßler-Wüstling Johanna Riedel -198 Administrative Director h. c./TU Dr. Hon.-Prof. Bratislava Rolf Pfrengle Ass.: Katja Backhaus-Nousch -160 Anja Hänig Secr.: -200 Confidential Representative (Ombudsperson) R. Schäfer Dr. Prof. -223 Institute for Complex Materials Dr. Prof. Eckert Jürgen -602 Secr.: Executive Board Publisher: Leibniz Institute for Solid State and Materials Research Dresden Executive Board Prof. Dr. Manfred Hennecke, Scientific Director Hon.-Prof. Dr. h. c. Rolf Pfrengle, Administrative Director Phone +49 351 46 59-0 Tel.: Fax: +49 351 46 59-540 Mail address PF 27 01 16 D-01171 Dresden Scientific Director Hennecke Manfred Dr. Prof. Langer Carola Ass.: Dr. -234 Katja ClausnitzerSecr.: -100

Visitors address Helmholtzstrasse 20 Institute for Metallic Materials Dr. Prof. Rudolf Schäfer (temp.) -223 Svea Fleischer Secr.: -102

D-01069 Dresden Equal Opportunity Commissioner work-life-balance: Head of task group -583Gelia Preuß Phone +49(0)351 4659 0 Mailing Address PF 27 01 16 D-01171 Dresden Leibniz Institute for Solid State and Materials Research Dresden Leibniz Institute for Fax +49(0)351 4659 540 Scientific Advisory Board Internet http://www.ifw-dresden.de e-mail [email protected] Manja Maluck -805 Scientific-Technical Council Scientific-Technical Head: Hagen Schmidt Dr. -278 Institute for Solid State Research Dr. Prof. Bernd Büchner -808 Kerstin Höllerer Secr.: -300 Contact Address Visitor’s Helmholtzstrasse 20 D-01069 Dresden Labour Council Head: Ulbrich Marek -306 Head: Prof. Dr. Maria-Roser Valenti, J.-W. Goethe-Univ. Frankfurt Goethe-Univ. J.-W. Maria-Roser Valenti, Dr. Head: Prof.