Stanford Institute for Materials and Energy Sciences (SIMES)

Field Budget Request for FY2015

FWP Page

Time‐Resolved Soft X-ray Materials Science at the LCLS & ALS 2

Diamondoid Science and Applications 10

Electronic and Magnetic Structure of Quantum Materials 14

Correlated Materials – Synthesis and Physical Properties 28

Spin Physics 36

Clathrin Biotemplating 39

Magnetization & Dynamic 43

Atomic Engineering Oxide Heterostructures: Materials by Design 46

High Energy Density Science at the SLAC National Accelerator Laboratory 52

Nanostructured Design of Sulfur Cathodes for High Energy Lithium-Sulfur Batteries 62

Pre-Lithiation of Silicon Anode for High Energy Li Ion Batteries 63

MEC User Workshop on High-Power Lasers 64

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Time‐Resolved Soft X-ray Materials Science at the LCLS and ALS FWP#: 10017 Time‐Resolved Soft X-ray Materials Science at the LCLS & ALS

Principal Investigator(s): T. P. Devereaux, Z.-X. Shen, Z. Hussain, A. Lindenberg, D. Reis, and W. Mao

Staff Scientists: Wei-Sheng Lee, Yi-De Chuang, Mariano Trigo, Hongchen Jiang Postdoctoral Scholars and Graduate Students: Thomas Henighan, Te Hu, Shigeto Hirai, Mason Jiang, Sanghee Nah, Michael Sentef, Renee Sher, Michael Shu, Peter Zalden, Qiaoshi Zeng

Overview:

This program connects concepts of ultrafast time-domain science with those for momentum- and energy-domain x-ray spectroscopy. The FWP consists of the single-investigator small group research (SISGR) program (Devereaux, Lee, Shen, Moritz, Hussain, Chuang) on time-resolved soft x-ray materials science at the Linac Coherent Light Source (LCLS) and the Advanced Light Source (ALS), merged with the recent addition of high pressure studies (Mao) and ultrafast activities (Lindenberg, Reis) on non-equilibrium phonon dynamics and phase transitions, nanoscale dynamics and ferroelectric oxide ultrafast processes. The combined activities bring a synergy to explore how materials behave under extreme conditions, driving lattice and charge conformational changes by applying short pulses, high fields, or high pressures. The purpose of this research is to develop a world-class program on the dynamics of complex materials using the x-ray beamlines available at LCLS to address the grand challenge problems of “emergence”, non-equilibrium dynamics, and to probe model systems for deep insights on materials for energy conversion, transport and efficiency.

Theoretical calculations and simulations conducted in parallel with experimental progress will help to establish a formalism for describing non-equilibrium physics of strongly correlated materials and provide additional insight to the generated experimental data. This activity requires the development of novel theoretical and computational tools and as well as the deployment of standard techniques designed to uncover the nature of the many-body state both in and out of equilibrium.

We have made substantial progresses on several research fronts to advance our understanding of complex materials through advanced x-ray based techniques coupled with advanced numerical simulations. These include LCLS- and synchrotron based experiments to further the study novel quantum materials and extend knowledge of time-domain based x-ray spectroscopy. In the following, we outline our progress through lists of bullets.

Progress in FY2014  Used large-scale exact diagonalization to investigate the nature of resonant inelastic x-ray scattering (RIXS) at the L-edge in cuprates, in particular the ability of RIXS to measure spin excitation in heavily-doped systems (C. J. Jia et al., Nature Communications 5, 3314 (2014) and a submission to Nature Materials). o We showed that L-edge RIXS can indeed provide a good proxy for measuring the spin dynamical structure factor which complements inelastic neutron scattering. o Utilizing quantum Monte Carlo calculations, as well as exact diagonalization, we demonstrated that even in heavily hole-doped compounds, the experimental RIXS signal indeed corresponds to persistent spin excitations at high-energies along the anti-ferromagnetic zone boundary. Our results reconcile the RIXS experiments with previous investigations using inelastic neutron and Raman techniques. o We predicted a striking asymmetry between hole- and electron-doped materials, which was recently confirmed in two separate experiments, one by members of the present FWP (arXiv:1308.4740).

 We have developed a microscopic understanding of lattice effects and the manifestation of electron-phonon coupling in RIXS spectra with the prospect of utilizing this technique to precisely determine the mode coupling in condensed matter systems.

 We have demonstrated the ability of non-resonant and resonant inelastic x-ray scattering to provide both real-space and real-time information about the flow of energy and charge in condensed matter systems. This opens the avenue

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Time‐Resolved Soft X-ray Materials Science at the LCLS and ALS FWP#: 10017

for a more complete mapping of charge-transfer and chemical reaction pathways using x-ray scattering techniques (Y. Wang et al, Phys. Rev. Lett. 112, 156402 (2014)).

 We analyzed the data taken in an experiment at LCLS, in which we studied lattice-driven striped dynamics via mid- IR pump and resonant x-ray probe on the striped nickelates. By tuning the mid-IR pump pulse to resonantly excite the breathing phonon, we observed lattice-driven striped dynamics. Surprisingly, the spin order is suppressed more than the charge order; furthermore, the recovery dynamics is notably different form that driven by optical pulse. We are now preparing a manuscript to publish these results.

 We analyzed the data taken in an experiment at LCLS, where we studied photo-induced dynamics in un-doped iron- pnictide, BaAs2Fe2 via optical-pump and x-ray scattering probe measurement. We observed coherent excitation of a As-Fe-As bond angle mode, which is crucial in determining the electronic structure as well as the emergence of the underlying spin density wave order. Through modeling the scattering form factor, atomic displacements during this photo-excited coherent oscillatory state can be determined. This information crucially complements other time- resolved electronic probes on the same compounds. In addition, our results indicate an intriguing temperature dependence, which might be related to the coupling with the underlying electronic fluctuations. We will perform the second measurement at the LCLS in July 2014 to confirm these observations.

 Experimental investigations of collective excitations in high TC-cuprates via high resolution state-of-the-art RIXS instruments worldwide. These investigations serve preparation experiments for identifying scientific cases of the later time-resolved q-RIXS experiments at the LCLS (expected in FY2016).

o We have investigated the doping evolution of collective excitations in the electron-doped cuprates. Surprisingly we observed magnetic excitation hardens upon electron-doping. Furthermore, a new branch of collective modes emanating from the zone center was also observed. Our observations provide a new perspective on the issue of asymmetry in the cuprate phase diagram with respect to electron and hole- doping. We have summarize our first observation in a manuscript, which is now under review (arXiv:1308.4740). In addition, we have also performed the second measurements at the Swiss Light Source (Feb. 2014) to map out a detailed doping evolution in the phase diagram. The analysis of these new results is in progress.

o We have formed new collaborations with RIXS group in National Synchrotron Radiation Research Center (NSRRC, Taiwan), where a high resolution and high throughput RIXS spectrometer with a novel AGS- AGM design is recently constructed. Using this instrument, we have performed momentum-dependent RIXS measurements on the striped cuprates La1.875Ba0.125CuO4 in April 2014. The analysis of the data is currently in progress. Technologically, evaluating the performance of such RIXS instrument is strategically important on the planning of a RIXS instrument at LCLS-II.

 Progress on the q-RIXS:

o Two modular X-ray emission spectrographs have been fully assembled and fiducialized. They will be ready for commissioning with synchrotron beam at the ALS after the ALS shutdown is over in July 2014.

o The components of third X-ray emission spectrograph have been pre-assembled and clean assembly will be carried out in summer 2014.

o The components for q-RIXS endstation are arriving and the assembling will be started in summer 2014. The assembling is expected to be completed before the end of 2014.

 We investigated how electron-phonon coupling manifests itself in the orbital excitation profile of transition metal systems at the L-edge (J. J. Lee et al., Phys. Rev. B 89, 041104R (2014), chosen as an Editors' Suggestion). This led to a new perspective on the nature of these excitations and an explanation for the relatively large observed broadening in terms of “dressing” with lattice excitations.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Time‐Resolved Soft X-ray Materials Science at the LCLS and ALS FWP#: 10017

 We have utilized HPC resources both in-house at SLAC as well as those available at the National Energy Research Scientific Computing Center (NERSC). We were awarded an initial allocation of 5,000,000 CPU-hrs for FY2014 which subsequently has increased to 11,000,000 CPU-hrs.

 We have used x-ray scattering techniques at LCLS to resolve the first steps in the nanocrystal shock-induced and light-induced structural transformations. These measurements identify a theoretically-predicted but not previously observed transient intermediate structural phase. They further show a new means of tomographically imaging dynamic nanoscale shape changes. This work is published as Wittenberg et al., Nano Lett. 14, 1995 (2014) with an additional paper now submitted.

 We have carried out the first time-resolved experiments at the Stanford Synchrotron Radiation Laboratory using a unique low-alpha mode to carry out measurements with ~10 picosecond time-resolution. In this work we were able to resolve the time-scales and dynamics of interfacial thermal transport across oxide interfaces, and further elucidate the coupling between light and strain in ferroelectric oxides. This work is published as Kozina et al., Struct. Dyn., 1, 034301 (2014).

 We carried out experiments in March of 2014 at LCLS probing terahertz-driven structural dynamics in ferroelectric oxides. These experiments were successful and showed large-amplitude structural changes induced by an all-optical bias in BaTiO3 thin films. The analysis of this work is ongoing and this work will soon be submitted. In parallel with this we have been investigating terahertz-induced processes in oxide ferroelectrics using nonlinear optical probes as an alternative means of dynamically resolving changes in the unit cell structure. These measurements show very large modulations in the nonlinear optical susceptibility (600%) and open up new possibilities for controlling the functionality of materials with light. This work is now submitted.

 We carried out experiments in March of 2014 at LCLS probing light-induced processes in phase-change materials. These experiments were successful and provide new information about the nucleation processes that occur during amorphous-crystalline and crystalline-amorphous structural transformations.

 We have published the first results on Fourier transform x-ray inelastic scattering [Trigo et al., Nat. Phys. 9, 790, 2013]. The experiments made use of the hard x-ray beamline at LCLS to achieve sub-meV resolution of collective modes in photoexcited materials spanning the full Brillouin zone. Peter Abbamonte featured the work in a News and Views article.

 We have carried out time-resolved optical and x-ray experiments on phonon-phonon interactions in the incipient ferroelectric and high ZT thermoelectric PbTe which shows large interactions between the soft TO and LA phonons.

 In collaboration with Herman Dürr, we have investigated the role of phonons in the ultrafast demagnetization of iron films on MgO.

 We are investigating the effects of pressure, doping, and temperature on the behavior of high Tc cuprates and collaborating with theory to interpret IXS and XAS measurements.

Expected Progress in FY2015

 Planned theory developments:

o Continue to exploit Krylov-based methods to advance our understanding of x-ray probes for systems driven out of equilibrium. This includes developing small-cluster exact diagonalization codes for pump-probe x- ray absorption (XAS), as well as the static and dynamic structure factors measured with resonant and non- resonant probes, especially at the L-edges of transition metal compounds. o Continue investigating direct RIXS at the L-edge to better characterize the nature of the response functions measured, and how to properly interpret those spectra in terms of simpler two-particle spin and charge response functions accessible through inelastic neutron or non-resonant scattering techniques. o Continue developing theory for x-ray spectra, especially RIXS, in magnetic fields.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Time‐Resolved Soft X-ray Materials Science at the LCLS and ALS FWP#: 10017

o Refine the theory and computational infrastructure for lattice effects and electron-phonon coupling revealed by RIXS.

 Experimental developments:

o Continue to investigate collective excitations in high Tc cuprates with a focus on the proximity of putative quantum critical points that are hinted by other measurements. If a QCP indeed exists, emergence of new collective modes and its influence on the elementary excitations, such as magnons and phonons, could be identified via momentum-resolved RIXS measurement. o Plan to investigate momentum dependent electron-phonon coupling strength in high-Tc cuprates. Our previous experimental and theoretical investigations (Phys. Rev. Lett. 110, 265502 (2013)), phonon excitations in RIXS provide a unique handle to extract the electron-phonon coupling strength. We plan to expand this work to extract the momentum-dependence electron-phonon coupling strength. This work will closely collaborate with the theorists in our FWP. o Commission experiments of q-RIXS endstation will be conducted at ALS. Using its unique capability of high data acquisition efficiency and continuously variable spectrometer angle, we plan to perform energy- resolved resonant diffraction and momentum-resolved RIXS measurements on classical correlated materials. o Continue investigating photo-induced dynamics; particularly those induced by long wavelength photons in the spectral range of THz and mid-IR that can resonant excite the materials at their characteristic energy scales. Time-resolved optical spectroscopy and time-resolved x-ray scattering at the LCLS will probe the response. o Complete analysis of recent LCLS experiments probing THz-driven dynamics in ferroelectric oxides. o Continue studies of electric-field-driven processes in phase-change materials. The goal of these studies is to understand the first steps in field-driven switching processes associated with crystalline-amorphous structural transformations and associated changes in band structure. Preliminary studies show that we can follow the ultrafast electronic and structural processes that represent the first steps in the threshold switching process. This work is now submitted. o Continue studies on time-resolved XRD on phase change materials in diamond anvil cells. o Complete analysis of LCLS experiments on laser-shocked SiO2 and H2O. o Complete analysis of LCLS beamtimes on Fe demagnetization and PbTe anharmonic phonons. o Study high pressure phonon dynamics of PbTe using pump-probe experiments in a diamond anvil cell. o Investigate CDW dynamics of phase and amplitude modes in rare-earth tri-tellurides at SACLA FEL and compare with competing theoretical models for the CDW formation. o Perform optical and x-ray coherent control experiments to identify the general mechanisms that give rise to temporal correlations seen in the collective modes at high-wavevector and extend their applications to complex materials. Expected Progress in FY2016

 We will continue theoretical and computational activities utilizing in-house resources at SLAC and HPC allocations at NERSC for our simulations.

 We plan to perform the first time-resolved RIXS measurement using q-RIXS endstation at LCLS.

 Continue investigating the collective dynamics with high-resolution momentum RIXS measurement. In FY2016, RIXS instrument will energy resolution better than 50 meV will be operational in several synchrotron facilities in the world (e.g. ESRF, NSLS-II, and TPS). New discoveries enabled by these new instruments are expected. Thus, it is important to continue these efforts. These efforts are strategically important to the continuation of our FWP, as well as the development of a next generation time-resolved RIXS instrument at the LCLS-II that can fully utilize the self-seeded FEL and high-repetition rate.

 Continue experimental progress on time and energy-resolved x-ray scattering to address the grand challenge problems of “emergence”, non-equilibrium dynamics, and to probe model systems for deep insights on materials for energy conversion, transport and efficiency.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Time‐Resolved Soft X-ray Materials Science at the LCLS and ALS FWP#: 10017

Collaborations Ament, Luuk, Strategic Research at ASML, The Netherlands; Analytis, J G, UC Berkeley; Ando, Yoichi, Osaka University; Banerjee, Tamalika, University of Groningen; Baumberger, Felix, U Geneva; Bluhm, Hendrik, Lawrence Berkeley National Laboratory (LBNL); Cataudella, V., Universit`a di Napoli Federico II; Chen, Cheng-Chien, Argonne National Laboratory; Chen, Yulin, Oxford University, England; Cheng, Hai- Ping, University of Florida; Chuang, Yi-De, LBNL; Tanja, UC Berkeley; Degiorgi, Leonardo, ETH Zurich, Switzerland; Delaire, Olivier, Oak Ridge National Laboratory; Fahy, Stephen, University College Cork; Freericks, James K., Georgetown University;.; Fujimori, Atsushi, University of Tokyo, Japan, Greven, Martin, University of Minnesota; Hackl, Rudi, Walther Meissner Institut, Bayerische Akademie der Wissenschaften, Germany; Hancock, Jason, University of Connecticut;; He, Rui-Hua, Boston College, Massachusetts; Hemminger,John C., UC Irvine; Hill, John, Brookhaven National Laboratory; Hirschfeld, Peter, University of Florida; Hussain, Zahid, LBNL; Johnson, Steven, ETH Zurich; Johnston, Steven, University of British Columbia, Canada; Kaindl, Robert A., LBNL; Kampf, Arno P., University of Augsburg; Kemper, Alexander F., LBNL; Kim, Changyoung, Yonsei University, South Korea; Kim, Young-June, University of Toronto, Canada; Krishnamurthy, H. R., Indian Institute of Science, Bangalore, India; Lee, Dung-Hai, UC Berkeley; Lipp, Magnus J.,LLNL; Liu , Amy Y., Georgetown University; Martin, L., UC Berkeley; Mazin, Igor I., Naval Research Laboratory; Meevasana, Worawat, Suranaree University of Technology, Thailand; Merlin, Roberto, U. Michigan; Mishchenko, Andrey S, RIKEN Advanced Science Institute, Japan; Monney, Claude, Fritz-Haber-Institut, Berlin, Germany; Nagaosa, Naoto, University of Tokyo; RIKEN Advanced Science Institute, Japan; Orenstein, Joseph, LBNL; Patthey, Luc, Paul Scherrer Institut, Switzerland; Sawatzky, George A., University of British Columbia, Canada; Scalapino, Douglas J., UC Santa Barbara; Scalettar, Richard T., UC Davis; Schmitt, Thorsten, Paul Scherrer Institute, Switzerland; Schoenlein, Robert W., LBNL; Sokolowski-Tinten, Klaus, University of Duisburg-Essen, Germany; Shastry, B. Sriram, UC Santa Cruz; Shen, Kyle M., Cornell University; Singh, Rajiv R. P., UC Davis; Stephenson, G.B., Argonne National Laboratory; Stock, Chris, NIST Center for Neutron Research; Indiana University Cyclotron Facility; Strocov, Vladimir N., Paul Scherrer Institute, Switzerland; Thomale, Ronny, University of Wurzburg, Germany; Tohyama, Takami, Kyoto University; Uchida, Shin-Ichi, University of Tokyo, Japan; van den Brink, Jeroen, IFW Dresden, Germany; van der Marel, Dirk, Université de Genève, Switzerland; van Veenendaal, Michel, Northern Illinois University, Argonne National Laboratory; Vernay, Francois, Université de Perpignan, France; Vishik, Inna, MIT; Yang, WanLi, LBNL; Yang, Wenge, CIW; Yabashi, Makina, RIKEN, Japan; Zaanen, Jan, University of Leiden, The Netherlands, Zhu, Diling, SLAC LCLS.

Publications for FY13 & FY14 (Oct 1st 2012 to date) Peer-Reviewed Journal Articles

1. Bandgap Closure and Reopening in CsAuI3 at High Pressure, Shibing Wang, Maria Baldini, Max Shapiro, Scott Riggs, Alexander F. Kemper, Zhao Zhao, Zhenxian Liu, Thomas P. Devereaux, Ted Geballe, Ian R Fisher, and Wendy L. Mao, submitted to Phys. Rev. B. 2. Real Space Visualization of Remnant Mott Gap and Magnon Excitations, Yao Wang, Chunjing Jia, Brian Moritz, and Thomas Devereaux, Phys. Rev. Lett. 112, 156402 (2014). 3. Narrowing of Band Gaps in Thin Films and Linear Arrays of Ordered TiO2 Nanoparticles, Yu Liu, James Taing, Cheng-Chien Chen, Adam P. Sorini, Ming H. Cheng, Alexandria M. Margarella, Hendrik Bluhm, Thomas P. Devereaux, and John C. Hemminger, submitted to J. Phys. Chem. 4. Asymmetry in Collective Excitations of Electron and Hole Doped Cuprate Superconductors, W. S. Lee, J. J. Lee, E. A. Nowadnick, W. Tabis, S. W. Huang, V.N. Strocov, E. M. Motoyama, B. Moritz, M. Greven, T. Schmitt, Z. X. Shen, and T. P. Devereaux, arXiv:1308.4740, submitted to Nat. Phys. 5. Ultrafast Lattice Dynamical Response to the Electronic Excitation of the Charge Density Wave in TbTe3, R. G. Moore, W. S. Lee, P. S. Kirchmann, Y. D. Chuang, A. F. Kemper, M. Trigo, L. Patthey, D. H. Lu, O. Krupin, M. Yi, D. A. Reis, D. Doering, P. Denes, W. F. Schlotter, J. J. Turner, G. Hay, P.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Time‐Resolved Soft X-ray Materials Science at the LCLS and ALS FWP#: 10017

Hering, T. Benson, J. -H. Chu, T. P. Devereaux, I. R. Fisher, Z. Hussain, and Z. -X. Shen, submitted to Phys. Rev. Lett. 6. Persistent Spin Excitations in Doped Antiferromagnets Revealed by Resonant Inelastic Light Scattering, C. J. Jia, E. A. Nowadnick, K. Wohlfeld, C.-C. Chen, S. Johnston, T. Tohyama, B. Moritz, and T. P. Devereaux, Nat. Commun. 5, 3314 (2014). 7. Charge-Orbital-Lattice Coupling Effects in the dd-Excitation Profile of One Dimensional Cuprates, J. J. Lee, B. Moritz, W. S. Lee, M. Yi, C. J. Jia, A. P. Sorini, K. Kudo, Y. Koike, K. J. Zhou, C. Monney, V. Strocov, L. Patthey, T. Schmitt, T. P. Devereaux, and Z. X. Shen, Phys. Rev. B 89, 041104(R) (2014) [Editors' Suggestion]. 8. Existence of Orbital Order and its Fluctuation in Superconducting Ba(Fe1-xCox) 2As2 Single Crystals Revealed by X-ray Absorption Spectroscopy, Y. K. Kim, W. S. Jung, G. R. Han, K.-Y. Choi, K.-H. Kim, C.-C. Chen, T. P. Devereaux, A. Chainani, J. Miyawaki, Y. Takata, Y. Tanaka, M. Ouara, S. Shin, A. P. Singh, J.-Y. Kim, C. Kim, Phys. Rev. Lett. 111, 217001 (2013). 9. Time-Dependent Charge and Spin Order Recovery in Striped Systems, Y. F. Kung, C.-C. Chen, A. F. Kemper, W.-S. Lee, B. Moritz, A. P. Sorini, and T. P. Devereaux, Phys. Rev. B 88, 125114 (2013). 10. Mapping of the Unoccupied States and Relevant Bosonic Modes Via the Time Dependent Momentum Distribution, A. F. Kemper, M. Sentef, B. Moritz, C. C. Kao, Z. X. Shen, J. K. Freericks, and T. P. Devereaux, Phys. Rev. B 87, 235139 (2013). 11. The Role of Lattice Coupling in Establishing Electronic and Magnetic Properties in Quasi-1D Cuprates, W. S. Lee, S. Johnston, B. Moritz, J. Lee, M. Yi, K. J. Zhou, T. Schmitt, L. Patthey, V. Strocov, K. Kudo, Y. Koike, J. van den Brink, T. P. Devereaux, and Z. X. Shen, Phys. Rev. Lett. 110, 265502 (2013). 12. Doping Evolution of Oxygen K-edge X-ray Absorption Spectra of Cuprate Superconductors Using a Three-Orbital Hubbard Model, C.-C. Chen, M. Sentef, Y. F. Kung, C. J. Jia, R. Thomale, B. Moritz, A. P. Kampf, T. P. Devereaux, Phys. Rev. B 87, 165144 (2013). 13. Real-Time Manifestation of Strongly Coupled Spin and Charge Order Parameters in Stripe- Ordered La1.75Sr0.25NiO4 Nickelate Crystals Using Time-Resolved Resonant X-Ray Diffraction, Y.D. Chuang, W. S. Lee, Y.F. Kung, A.P. Sorini, B. Moritz, R. G. Moore, L. Patthey, M. Trigo, D. H. Lu, P. S. Kirchmann, M. Yi, O. Krupin, M. Langner, Y. Zhu, S. Y. Zhou, D. A. Reis, N. Huse, J. S. Robinson, R. A. Kaindl, R. W. Schoenlein, S.L. Johnson, M. Forst, D. Doering, P. Denes, W. F. Schlotter, J. J. Turner, T. Sasagawa, Z. Hussain, Z. X. Shen, and T. P. Devereaux, Phys. Rev. Lett. 110, 127404 (2013). 14. X-ray Emission Spectroscopy of Cerium Across the γ-α Volume Collapse Transition, M. J. Lipp, A. P. Sorini, J. Bradley, B. Maddox, K. T. Moore, H. Cynn, T. P. Devereaux, Y. Xiao, P. Chow, and W. J. Evans, Phys. Rev. Lett. 109,195705 (2012) 15. Uncovering selective excitations using the resonant profile of indirect inelastic x-ray scattering in correlated materials: observing two-magnon scattering and relation to the dynamical structure factor, C. J. Jia, C.-C. Chen, A. P. Sorini, B. Moritz, and T. P. Devereaux, New J. Phys. 14,113038 (2012) 16. Large-Amplitude Spin Dynamics Driven by a THz Pulse in Resonance with an Electromagnon, T. Kubacka, J.A. Johnson, M.C. Hoffmann, C. Vicario, S. de Jong, P. Beaud, S. Grübel, S-W. Huang, L. Huber, L. Patthey, Y-D. Chuang, J.J. Turner, G.L. Dakovski, W-S. Lee, W. Schlotter, R. G. Moore, C. Hauri, S.M. Koohpayeh, V. Scagnoli, G. Ingold, S.L. Johnson, U. Staub, Science 343, 1333 (2014).

17. Melting of Charge Stripes in Vibrationally Driven La1.875Ba0.125CuO4: Assessing the Respective Roles of Electronic and Lattice Order in Frustrated Superconductors, M. Först, R. I. Tobey, H. Bromberger, S. B. Wilkins, V. Khanna, A. D. Caviglia, Y.-D. Chuang, W. S. Lee, W. F. Schlotter, J. J. Turner, M. P. Minitti, O. Krupin, Z. J. Xu, J. S. Wen, G. D. Gu, S. S. Dhesi, A. Cavalleri, and J. P. Hill, Phys. Rev. Lett. 112, 157002 (2014). 18. Photoinduced melting of magnetic order in the correlated electron insulator NdNiO3, A. D. Caviglia, M. Först, R. Scherwitzl, V. Khanna, H. Bromberger, R. Mankowsky, R. Singla, Y.-D. Chuang, W. S. Lee, O. Krupin, W. F. Schlotter, J. J. Turner, G. L. Dakovski, M. P. Minitti, J. Robinson, V. Scagnoli, S. B.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Time‐Resolved Soft X-ray Materials Science at the LCLS and ALS FWP#: 10017

Wilkins, S. A. Cavill,*, M. Gibert, S. Gariglio, P. Zubko, J.-M. Triscone, J. P. Hill, S. S. Dhesi, and A. Cavalleri, Phys. Rev. B, 88, 220401 (2013). 19. Ultrafast charge localization in a stripe-phase nickelate, G. Coslovich, B. Huber, W. S. Lee, Y.-D. Chuang, Y. Zhu, T. Sasagawa, Z. Hussain, H.A. Bechtel, M.C. Martin, Z.-X. Shen, R.W. Schoenlein and R.A. Kaindl, Nature Comm. 4, 2643 (2013). 20. Speed Limit of the insulator-metal transition in magnetite, S. de Jong, R. Kukreja, C. Trabant, N. Pontius, C. F. Chang, T. Kachel, M. Beye, F. Sorgenfrei, C. H. Back, B. Brauer, W. F. Schlotter, J. J. Turner, O. Krupin, M. Doehler, D. Zhu, M. A. Hossain, A. O. Scherz, D. Fausti, F. Novelli, M. Esposito, W. S. Lee, Y. D. Chuang, D. H. Lu, R. G. Moore, M. Yi, M. Trigo, P. Kirchmann, L. Pathey, M. S. Golden, M. Buchholz, P. Metcalf, F. Parmigiani, W. Wurth, A. Fohlisch, C. Schussler-Langegeine, and H. A. Durr, Nature Matt. 12, 882 (2013). 21. Real-time visualization of nanocrystal solid-solid transformation pathways, J.S. Wittenberg, T.A. Miller, E. Szilagyi, K. Lutker, F. Quirin, W. Lu, H. Lemke, D. Zhu, M. Chollet, J. Robinson, H. Wen, K. Sokolowski-Tinten, A.P. Alivisatos, A.M. Lindenberg, Nano Lett. 14, 1995 (2014). 22. Measurement of transient atomic displacements in thin films with picosecond and femtometer resolution, M. Kozina, T. Hu, J.S. Wittenberg, E. Szilagyi, M. Trigo, T.A. Miller, C. Uher, A. Damodaran, L. Martin, A. Mehta, J. Corbett, J. Safranek, D.A. Reis and A.M. Lindenberg, Struct. Dyn. 1, 034301 (2014). 23. Ultrafast sub-threshold photo-induced response in crystalline and amorphous GeSbTe thin films, M. J. Shu, I. Chatzakis, Y. Kuo, P. Zalden, A. M. Lindenberg, Appl. Phys. Lett. 102, 201903 (2013). 24. Intense THz pulses from SLAC electron beams using coherent transition radiation, Z. Wu, A.S. Fisher, J. Goodfellow, M. Fuchs, D. Daranciang, M. Hogan, H. Loos, A.M. Lindenberg, Rev. Sci. Instrum. 84, 022701 (2013). 25. The mechanism of ultrafast structural switching in superionic copper (I) sulfide nanocrystals, T.A. Miller, J.S. Wittenberg, H. Wen, S. Connor, Y. Cui, A.M. Lindenberg, Nat. Commun. 4, 1369 (2013). 26. Ultrafast electric-field-induced processes in GeSbTe phase-change materials, M. Shu, P. Zalden, F. Chen, B. Weems, I. Chatzakis, F. Xiong, R. Jeyasingh, M. Hoffmann, E. Pop, H.-S.P. Wong, M. Wuttig, A.M. Lindenberg (Submitted to Appl. Phys. Lett.).(2014). 27. Below gap optical absorption in GaAs driven by intense, single-cycle coherent transition radiation, J. Goodfellow, M. Fuchs, D. Daranciang, S. Ghimire, F. Chen, H. Loos, D. Reis, A.S. Fisher, A.M. Lindenberg. (Submitted to Optics Express). (2014) 28. Femtosecond x-ray tomography of nanocrystals at extreme strains, E. Szilagyi, J. Wittenberg, T.A. Miller, E. Szilagyi, K. Lutker, F. Quirin, H. Lemke, D. Zhu, M. Chollet, J. Robinson, H. Wen, K. Sokolowski-Tinten, A.P. Alivisatos, A.M. Lindenberg. (Submitted to Nature Nanotech.) (2014) 29. Evidence for photo-induced monoclinic metallic VO2 under high pressure, W.-P. Hsieh, M. Trigo, D. A.Reis, G. Andrea Artioli, L. Malavasi, and W. L. Mao, Applied Physics Letters 104, 021917 (2014). 30. Fourier-transform inelastic x-ray scattering from time- and momentum-dependent phonon-phonon correlations, M. Trigo, M. Fuchs, J. Chen, M. P. Jiang, M. Cammarata, S. Fahy, D. M. Fritz, K. Gaffney, S. Ghimire, A. Higginbotham, S. L. Johnson, M. E. Kozina, J. Larsson, H. Lemke, A. M. Lindenberg, G. Ndabashimiye, F. Quirin, K. Sokolowski-Tinten, C. Uher, G. Wang, J. S. Wark, D. Zhu, and D. A. Reis. Nat Phys. 9, 790 (2013). 31. Fractional Non-Cubic Power Law for Density of Metallic Glasses, Q. Zeng, Y. Kono, Y. Lin, Z. Zeng, J. Wang, S. V. Sinogeikin, C. Y. Park, Y. Meng, W. Yang, H.-k. Mao, and W. L. Mao, Phys. Rev. Lett., accepted. 32. Pressure induced novel triple layered and metallic phases of Ag2Se, Z. Zhao, S. Wang, A. Oganov, P. Chen, Z. Liu, W. L. Mao, Phys. Rev. B, accepted. 33. Pressure induced second-order structural and electronic transition in Sr3Ir2O7, Z. Zhao, S. Wang, T. F. Qi, Q. S. Zeng, S. Hirai, P. P. Kong, L. Li, C. Park, S. J. Yuan, C. Q. Jin, G. Cao, W. L. Mao, J. Phys.: Condens. Matter, accepted. 34. High pressure Raman and X-ray diffraction study of [121] Tetramantane, F. Yang, Y. Lin, J. E. P. Dahl, R. M. K. Carlson, W. L. Mao, J. Phys. Chem. C, doi:10.1021/jp500431, 2014.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Time‐Resolved Soft X-ray Materials Science at the LCLS and ALS FWP#: 10017

35. Strain derivatives of Tc in HgBa2CuO4: The CuO2 plane alone is not enough,S. Wang, J. Zhang, J. Yan, X-J Chen, V. V. Struzhkin, W. Tabis, N. Barisic, M. Chan, C. Dorow, X. Zhao, M. Greven, W. L. Mao, T. Geballe, Phys. Rev. B 89, 024515 (2014). 36. Densification process of GeO2 glass: High pressure transmission x-ray microscopy study, Y. Lin, Q. S. Zeng, W. Yang, and W. L. Mao, Appl. Phys. Lett. 103, 261909 (2013). 37. High-pressure Raman spectroscopy of phase change materials,W. P. Hsieh, P. Zalden, M. Wuttig, A. M. Lindenberg, and W. L. Mao, Appl. Phys. Lett. 103, 191908 (2013). 38. Pressure induced structural transitions and metallization in Ag2Te, Z. Zhao, S. Wang, H. Zhang, and W. L. Mao, Phys. Rev. B 88, 024120 (2013). 39. The effect of composition on pressure-induced devitrification in metallic glasses, Q.S. Zeng, W. L. Mao, H. Sheng, Z. Zeng, Q. Hu, Y. Meng, H. Lou, F. Peng, W. Yang, S. V. Sinogeikin and J. Z. Jiang, Appl. Phys. Lett. 102, 171905 (2013). 40. Pressure-induced tetragonal-orthorhombic phase transitions in CeRuPO,S. Hirai, Y. Kamihara, A. Wakatsuki, M. Matoba, and W. L. Mao, Appl. Phys. Lett. 102, 051917 (2013). 41. Novel pressure-induced transitions in Co3O4, S. Hirai and W. L. Mao, Appl. Phys. Lett. 102, 041912, (2013). 42. Giant displacement at a magnetic transition in metastable Mn3O4, S. Hirai, A. M. dos Santos, M. Shapiro, J. J. Molaison, N. Pradhan, M. Guthrie, C. A. Tulk, I. R. Fisher, W. L. Mao, Phys. Rev. B 87, 014417 (2013).

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Diamondoid Science and Applications FWP#: 10018 Diamondoid Science and Applications

PIs: Nicholas A. Melosh (FWP lead), Peter R. Schreiner, Z. X. Shen Staff Scientists: J. E. P. Dahl Postdocs and Students: Hitoshi Ishiwata, Fei Hua Li, Vijay Narasimhan, Daniel Riley, Kunal Sahasrabuddhe, Boryslav A. Tkachenko, and Karthik Thimmavajjula

Overview Diamondoids are unique new carbon-based nanomaterials consisting of 1–2 nanometer, fully hydrogen-terminated diamond particles. Unlike their conjugated counterparts, graphene or carbon nanotubes, the carbon atoms in diamondoids are sp3-hybridized, leading to unique electronic and mechanical properties. Diamondoids behave much like small molecules, with atomic-level uniformity, flexible chemical functionalization, and systematic series of sizes, shapes and chiralities. At the same time diamondoids offer more mechanical and chemical stability than small molecules, and vastly superior size and shape control compared to inorganic nanoparticles. This family of new carbon nanomaterials is thus an ideal platform for approaching the grand challenges of energy flow at the nanoscale and synthesis of atomically perfect new forms of matter with better precision than any other nanomaterials system. This program explores and develops diamondoids as a new class of functional nanomaterials based upon their unique electronic, mechanical, and structural properties. This includes all phases of investigation, from diamondoid isolation from petroleum, chemical functionalization, and molecular assembly, as well as electronic, optical and theoretical characterization. We have currently focused on three areas of research: synthesis, electronic properties, and thin film growth. This naturally requires the broad expertise and collaboration between a number of investigators to successfully approach tackle these problems. This approach has yielded fruit, enabling synthesis of a number of new compounds, and exploration of their structural and electronic properties. In particular the ability of these materials to control the flow of electrons and emitted electron energy at the molecular level is an exciting direction for mastering energy flow at the nanoscale. The team meets biweekly to review current progress and initiate new ideas.

Progress in FY2014 This year we focused on three major areas: new materials and novel diamondoid synthesis. In particular, we have been interested in synthesizing new low dimensional metal chalcogenides through diamondoid-mediated assembly, which have emerged with a diverse range of electronic, optical, mechanical, and catalytic properties. Recent discoveries have shown low-dimensional materials with exceptional properties such as high-mobility semiconductors, high-Tc superconductors, and topological insulators. Material control at the few-atom level is critical for new material designs, which has long been one of the main goals of metal-organic frameworks (MOFs) and supramolecular assemblies. However in these approaches it has been difficult to balance the competition between covalent bonding and non- covalent assembly to create structures that are neither single-atom polymeric backbones, nor three dimensional, interconnected crystals. Our approach has been to harness the remarkably strong intermolecular dispersion of diamondoid molecules to force metal chalcogenide network growth to occur within a confined reaction volume set by the self-assembly of the diamondoid cages. Unlike metal organic frameworks or block copolymer-directed synthesis, the products may form crystalline, multi-atom thick molecular rods that may retain band gaps in the visible region. The approach works for a variety of diamondoids and related cage molecules with various metal ions, with the ligand modulating the metal ions’ influence over the final covalent bonding and coordination number.1 The unique interplay between strong non-covalent interactions and covalent bonding leads to new metal organic chalcogenide materials with controlled bulk morphologies from nanowires to large single crystals. We have recently shown that dipole-dipole interactions between ligands can direct different chalcogen crystal structure in addition to steric and dispersion forces.1

For new diamondoid synthetic targets, we have prepared several of the initially proposed functional diamondoid derivatives such as the next member of diamondoid dimers with the longest alkane C–C bonds. The metal-induced coupling of tertiary diamondoid bromides gave highly sterically congested hydrocarbon (hetero)dimers with exceptionally long central C–C bonds of up to 1.71 Å in 2-(1-diamantyl)[121]tetramantane. These dimers are thermally very stable even at temperatures above 200 °C, which is not in line with common C–C bond length versus bond strengths correlations. The extraordinary stabilization arises from numerous intramolecular van-der-Waals attractions between the neighboring H-terminated diamond-like surfaces. The C–C bond rotational dynamics of 1-(1- adamantyl)diamantane, 1-(1-diamantyl)diamantane, 2-(1-adamantyl)triamantane, 2-(1-diamantyl)triamantane, and 2-

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Diamondoid Science and Applications FWP#: 10018

(1-diamantyl)[121]tetramantane were studied through variable-temperature 1H- and 13C-NMR spectroscopies. The shapes of the inward (endo) CH surfaces determine the dynamic behavior, changing the central C–C bond rotation barriers from 7 to 33 kcal mol–1. We probe the ability of popular density functional theory (DFT) approaches (including BLYP, B3LYP, B98, B3LYP-Dn, B97D, B3PW91, BHandHLYP, B3P86, PBE1PBE, wB97XD, and M06- 2X) with 6-31G(d,p) and cc-pVDZ basis sets to describe such an unusual bonding situation. Only functionals accounting for dispersion are able to reproduce the experimental geometries, while most DFT functionals are able to reproduce the experimental rotational barriers due to error cancellations. Computations on larger diamondoids reveal that the interplay between the shapes and the sizes of the CH surfaces may even allow the preparation of open-shell alkyl radical dimers (and possibly polymers) that are strongly held together exclusively by dispersion forces. This work challenges common views on the “chemical bond” and has triggered broad discussions on the role of London dispersion interactions in molecular chemistry.

Secondly, we described a convenient four-step preparation of 1-vinyladamantane, 1-vinyldiamantane, and 4,9-divinyl- diamantane from the respective diamondoid acetic acids in 50–80% isolated product yields involving esterification, reduction, and hydrobromination / dehydrobromination. These derivatives are valuable intermediates in the preparation of the corresponding alkynes, for polymerization, and for the preparation of larger diamondoid assemblies through, for instance, double bond metathesis.

Thirdly, we developed an effective three-step chromatography-free sequence for the preparation of apical monohydroxy derivatives of diamantane, triamantane, and [121]tetramantane from the corresponding bis-apical diols utilizing tert-butyldimethylsilyl chloride as the mono-silylating agent. The procedure was successfully applied to the monoprotection of several other aliphatic and aromatic diols. Additionally, 9-Aminodiamantan-4-carboxylic acid, which has significant potential in material sciences, was prepared through Ritter reaction of 4,9-dihydroxy diamantane in trifluoroacetic acid.4 Monoprotection of with TBDMSCl is effective due to the low solubility of the mono- substituted product that prevents further silylation. The monoprotection efficiency for triamantane and tetramantane diols is only slightly lower and provides access to apical monoalcohols with excellent yields. Product isolation through simple crystallization avoids chromatographic steps, making this method amenable to large scale. The monoacetamidation of the diols under Ritter reaction conditions in TFA is also effective and allows the reduction of the preparative steps towards 9-aminodiamantan-4-carboxylic acid from the readily available diol. Our new method provides many key diamondoid derivatives that have high potential in nanotechnology.3

Finally, we developed an effective sequence for the preparation of phosphonic acid derivatives of the diamondoids diamantane, triamantane, [121]tetramantane, and [1(2,3)4]pentamantane through the reactions of the corresponding 5 diamondoid hydroxy derivatives with PCl3 in sulfuric or trifluoroacetic acid. Diamondoid phosphonates can be used to create monolayers on oxide surfaces for the construction of new diamondoid-based electronic devices.

Expected Progress in FY2015 Given the success of diamondoid-directed assembly and that many of the most interesting chalcogenide systems have Selinium rather than sulfur, we plan to prepare Se-modified diamondoids or similarly rigid molecules. As outlined in the original proposal, we plan on preparing completely rigid, nm-sized hydrocarbon structures are accessible through the coupling of diamondoids through their secondary positions. Only one such olefin, adamantylideneadamantane, has been reported in the literature and it displays some remarkable properties. Such coupled structures are accessible through McMurry reactions of the respective (di)ketones that can be prepared by direct oxidation of the diamondoids; this methodology also has to be developed further as it is currently low-yielding. The vinyl diamondoids and longer unsaturated at the diamondoid terminus will also be used to attempt metathesis reactions to prepared end-caped diamondoid “wires” that should be very stable and represent electronically coupled diamondoids. As diamond itself has been suggested as an organic wire this will enable us to examine the properties of the various diamondoids within and as end caps of π-conjugated systems. Our studies also aim at elucidating graphitization and diamond surface defects. As many properties of diamond materials can be traced back to surface impurities, the preparation of unsaturated larger diamondoid particles with well-defined structures can help interpret these findings (e.g., EAs, IPs, fluorescence etc.), especially when probed with the most modern physical measurement techniques available at SIMES.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Diamondoid Science and Applications FWP#: 10018

Expected Progress in FY2016 Among developing further methods for the preparation of an even broader variety of functional diamondoid derivatives, we will also plan the preparation of a variety of diamondoid-CNT adducts, later also including substituents that would allow additional tuning of the emission characteristics (R = OMe, NR2). As the thermal stability of the diene adducts is low (retro Diels-Alder reaction occurs at about 120 °C) we will prepare these for comparison and as possibly as a means to separate CNTs through differences in reactivities and solubilities. We will then focus on the preparation of the corresponding azomethine-CNT adducts that should be considerably more stable; adding azomethine derivatives (prepared from the respective amines) to fullerenes/CNTs is known. The adducts will then be thoroughly characterized chemically and physically (especially I/V curves via STS) with a keen eye on single- molecule electronics and the dependence of on the size, shape, attachment geometry, and functionalization (R) of the diamondoids to CNTs.

Collaborations 1. Rodney Rouoff (UT Austin) 2. Philip Hemmer (Texas A&M) 3. Jean-Cyrille Hierso (Institut de Chimie Moléculaire de l'Université de Bourgogne, Dijon, France) 4. Andrey A. Fokin (Kiev Polytechnic Institute, Kiev, Ukraine) 5. Thomas Möller (TU Berlin, Germany)

Publications for FY13 & FY14 (Oct 1st 2013 to date) Peer-Reviewed Journal Articles 1. Supramolecular Control of Metal Chalcogenide Bonding and Band Gap. J. Nathan Hohman, Hao Yan,

Diego Solis-Ibarra, Bin Wu, Karthik T. Narasimha, Fei Hua Li, Yifan Kong, Jason K. Middleton, Ryan Swoboda, Arturas Vailionis, Jeremy E. P. Dahl, Robert M. K. Carlson, Boryslav A. Tkachenko, Andrey A. Fokin, Peter R. Schreiner, Zhi-Xun Shen, Nicholas A. Melosh, submitted 3.11.2014

2. Selective Preparation of Diamondoid Phosphonates. Functionalized Nanodiamonds, part 44. Andrey A. Fokin, Raisa I. Yurchenko, Boryslav A. Tkachenko, Natalie A. Fokina, Maria A. Gunawan, Didier Poinsot, Jeremy E. P. Dahl, Robert M. K. Carlson, Michael Serafin, Hélène Cattey, Jean-Cyrille Hierso, and Peter R. Schreiner submitted 09.04.2014.

3. Efficient preparation of apically substituted diamondoid derivatives. Functionalized Nanodiamonds, part 39. Paul Kahl, Boryslav A. Tkachenko, Anatoliy A. Novikovsky, Jonathan Becker, Jeremy E. P. Dahl, Robert M. K. Carlson, Andrey A. Fokin, and Peter R. Schreiner Synthesis 2014, 787–798. DOI: 10.1055/s-0033-1338583.

4. Diamondoids: Functionalization and subsequent applications of perfectly defined molecular cage hydrocarbons. Functionalized Nanodiamonds, part 41. Maria A. Gunawan, Jean-Cyrille Hierso, Didier Poinsot, Andrey A. Fokin, Natalie A. Fokina, Boryslav A. Tkachenko, and Peter R. Schreiner, New. J. Chem. 2014, 38, 28–41. DOI: 10.1039/c3nj00535f. Highlight: inside front cover of this issue.

5. Covalent Attachment of Diamondoid Phosphonic Dichlorides to Tungsten Oxide Surfaces. Functionalized Nanodiamonds, part 40. Fei Hua Li, Jason D. Fabbri, Raisa I. Yurchenko, Alexander N. Mileshkin, James N. Hohmann, Hao Yan, Honyuan Yuan, Ich C. Tran, Trevor Willey, Michael Bagge- Hansen, Jeremy E. P. Dahl, Robert M. K. Carlson, Andrey A. Fokin, Peter R. Schreiner, Zhi-Xun Shen, Nicholas A. Melosh Langmuir 2013, 29, 9790–9797. DOI: 10.1021/la401781e.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Diamondoid Science and Applications FWP#: 10018

6. Evidence of Diamond Nanowires Formed inside Carbon Nanotubes from Diamantane Dicarboxylic Acid. Jinying Zhang, Zhen Zhu, Yanquan Feng, Hitoshi Ishiwata, Yasumitsu Miyata, Ryo Kitaura, Jeremy E. P. Dahl, Robert M. K. Carlson, Natalie A. Fokina, Peter R. Schreiner, David Tomanek, Hisanori Shinohara Angew. Chem. Int. Ed. 2013, 52, 3717–3721. Angew. Chem. 2013, 125, 3805– 3809. DOI: 10.1002/anie.201209192. Designated as a “Hot paper”; Highlights: a) Inside cover of this issue; b) Phys.org, March 6, 2013. c) Chemie.de, March 2013. d) Innovations Report, March 6, 2013. d) TechniScience, March 2013. e) e! Science News, March 6, 2013. f) GIT Laboratory Journal, March 2013.

7. Preparative Synthesis of Vinyl Diamondoids. Functionalized Nanodiamonds, part 36. Andrey A. Fokin, Ekaterina D. Butova, Anastasiya V. Barabash, Nhan N. Huu, Boryslav A. Tkachenko, and Peter R. Schreiner Synth. Commun. 2013, 43, 1772–1777.

8. Electronic structure tuning of diamondoids through functionalization. Functionalized Nanodiamonds, Part 35. Torbjörn Rander, Matthias Staiger, Robert Richter, Tobias Zimmermann, Lasse Landt, David Wolter, Jeremy E. P. Dahl, Robert M. K. Carlson, Boryslav A. Tkachenko, Natalie A. Fokina, Peter R. Schreiner, Thomas Möller, and Christoph Bostedt J. Chem. Phys. 2013, 135, 024310 (1–7).

9. Wang, F., Melosh, N.A. Power-independent wavelength determination by hot carrier collection in metal-insulator-metal devices. Nature Communications 4, 1711 (2013).

10. Li, F.H. et al. Covalent Attachment of Diamondoid Phosphonic Acid Dichlorides to Tungsten Oxide Surfaces. Langmuir 29, 9790-9797 (2013).

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Electronic and Magnetic Structure of Quantum Materials FWP#: 10027 Electronic and Magnetic Structure of Quantum Materials Principal Investigator(s): Zhi-Xun Shen, Thomas Devereaux Staff Scientists: Makoto Hashimoto, Patrick Kirchmann, DongHui Lu, Robert Moore, Brian Moritz Postdoctoral Scholars and Graduate Students: Martin Claassen, Charles de Bourcy, Yu He, Edwin Huang, Chunjing Jia, Stuart Koppell, Yvonne Kung, James Lee, Dominic Leuenberger, Wei Li, Shenxiu Liu, Benjamin Nosarzewski, Nachum Plonka, Elliott Rosenberg, Jonathan Sobota, Krzysztof Wohlfeld, Ming Yi, Jin Min Yoon, Yan Zhang, Yi Zhang

Overview We have made substantial progress on several research fronts to advance our understanding of complex materials through advanced photoelectron spectroscopy techniques coupled with advanced numerical simulations. These include synchrotron-based experiments to study novel superconductors and related materials, to develop time resolved photoelectron spectroscopy, to develop in-situ materials synthesis capability. These experiments are complemented by closely integrated theoretical simulation and investigations that study model systems with strongly coupled degrees of freedom under equilibrium and non-equilibrium conditions. In the following, we outline our progress through lists of bullets.

Progress in FY2014  We have discovered a new class of topological quantum materials, in collaboration with Yulin Chen of Oxford Univ.. o Discovery of three-dimensional Dirac Semimetal Na3Bi (Z.K. Liu et al., Science, 343, 864 (2014)). Unlike previously discovered topological insulators where the non-trivial state resides in the surface, the topologically protected non-trivial state of these materials resides in the bulk. These bulk Dirac bands also have very high velocity as those of the surface state. o Discovery of stable three dimensional Dirac Semimetal Cd3As2 (Z.K. Liu et al., Nature Materials, accepted) o Discovery of a Single Topological Dirac Fermion in a Strong Inversion Asymmetric System (Nature Physics, 9, 704 (2013))  We have shown direct spectroscopic evidence for the competition between the pseudogap and superconductivity by studying the detailed temperature dependence of the ARPES spectra of Bi2212 family of cuprate superconductors (submitted to Nature Materials, under review, arXiv:1405.5199). This work adds one more dimension to microscopic origin for the rich physics exhibited in the cuprate phase diagram (Invited Review for Nature Physics, submitted, ) o Antagonistic spectral weight singularity at Tc, which is a profound signature for competition between the order parameters for the pseudogap and superconductivity. o Disappearance of the competition at p > 0.22 around Tc revealed by the doping dependence of the spectral weight singularity o The ground state pseudogap critical point at p~0.19, which is at lower doping than p~0.22, suggesting the reentrant behavior of the pseudogap phase boundary beneath the superconducting dome in the cuprate phase diagram. o Spectral weight and spectral lineshape reproduced by simulation where density wave based pseudogap, coupling of electron to collective modes and superconductivity all contribute.  The temperature and doping evolution of the electronic structure in the lightly doped LaSrCuO family has been investigated to reveal how the Mott insulator evolves into high-Tc superconductors, especially focusing on the gap opening at the d-wave node with unknown origin. o Existence of the nodal gap in underdoped superconducting LSCO, which monotonically becomes smaller with hole doping, but extends up to near optimal doping. o Non-trivial temperature dependence of the nodal gap suggests its interaction with d-wave superconductivity o Potential underlying quantum critical point, with distinct symmetry from d-wave superconductivity, suggested by comparing with theoretical proposals. Particularly, broken-time reversal symmetry is an interesting candidate for the origin of the nodal gap. o Correlation between the polaronic excitations and the gap at the nodal momentum (fully gapped Fermi surface) is suggested

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Electronic and Magnetic Structure of Quantum Materials FWP#: 10027

 Superconducting gap and electron-boson coupling possibly closely related to superconductivity mechanism was studied in the Hg-based cuprates superconductors for the first time with laser-ARPES. (arXiv:1402.2215) o The d-wave superconducting gap was identified and found to have a maximum of 39 meV o A kink feature that shows strong temperature evolution across Tc was observed o Material dependence of the energy gap, nodal dispersion, and kink gave us the insight into the relationship between the mode-coupling and Tc.  Investigation of superconducting properties without the influence of the pseudogap in extremely overdoped Bi2212 o Simple d-wave superconducting gap on the entire Fermi surface. o BCS-like temperature dependence of the gap with unexpected temperature scale. o Multiple kink features in the nodal dispersion with distinct temperature scales suggest specific bosonic excitations might be responsible for the long-sought pairing glue. o Confirmed that this is an ideal system to study d-wave superconductivity in cuprates and identify the bosonic mode directly related with superconductivity.  Supplied Bi2212 to a number of collaborative groups to study the property of exfoliated Bi2212, specific heat and liquid gating.  Comparison of the tomographic density of states (TDOS) obtained from ARPES measurements with a theoretical calculation to investigate the pairing glue (collaboration with Doug Scalapino, UCSB) o Temperature dependent high quality TDOS spectra at momenta where SC is the half size of the antinodal gap.  We have directly observed bulk charge modulations in optimally-doped Bi2212 using energy-resolved inelastic soft x-ray scattering (arXiv:1403.0061) o Direct evidence for bulk soft charge collective modes (CCMs) at momentum transfer q ~ 0.28 r.l.u. o The signal is stronger at T ~ Tc than lower T. o Suggesting that soft CCMs are intrinsic and ubiquitous properties of high-temperature cuprate superconductors, intertwined with superconductivity.  We have investigated the impurity and disorder effect on superconducting and pseudogap, and have shown that cation substitution is not necessary for the deviation of the gap function from simple d-wave form, suggesting that the deviation is an intrinsic property in the underdoped cuprates. (arXiv: 1405.4961) o Deviation from simple d-wave form in underdoped Bi2212 samples without cation substitution. o Strong photon energy dependence of the antinodal coherence peak in underdoped Bi2212, which could affect the evaluation of the gap size around the antinode. o Importance of the high-energy resolution measurements to correctly determine the gap size.  Experimental determination of superconductivity in graphitic derived electronic state in CaC6 (Nature comm. 5 3493 (2014)) o Distinctly resolve both its intercalant-derived interlayer band and its graphene-derived π* band. o The opening of a superconducting gap in the π* band and discovering a substantial contribution to the total electron–phonon-coupling strength from the π*-interlayer interband interaction within BCS treatment o Providing a complete account for the superconducting mechanism in graphite intercalation compounds o Lending support to the idea of realizing superconducting graphene by creating an adatom superlattice  Angle-resolved photoemission study of Ln:KRhO2 (Ln = Sm, Dy, Ho). o Mapping out the band structure. Identifies three Rh bands that are mostly responsible for low energy excitation. o Comparison with its isostructural counterpart NaCoO2 in search for the missing K pocket o Tuning K doping continuously to look for Lifshitz transition and charge order at ½ doping o Ruling out long-range magnetic order induced Fermi surface reconstruction for low temperature metal-insulator transition in Ln-doped system o Discovering a distinct bosonic mode that couples to low energy A1g band, which may have laid foundation for high energy polaronic excitations  Universal orbital-selective Mott physics in FeSe film, KFe2Se2, and Fe(Te,Se) chalcogenide systems. o The dxy orbital is observed to be selectively strongly renormalized compared to other orbitals in all these chalcogenide systems. o All iron chalcogenide systems exhibit temperature-induced crossover to the orbital-selective Mott phase. o Correlation between the degree of dxy band renormalization and temperature scale of orbital-selective Mott transition is observed, reflecting how close the system is proximity to the orbital-selective Mott phase.  Dynamical electronic phase competition in underdoped Ba1-xKxFe2As2 family of pnictide superconductors (M. Yi et al. Nature Comm., 5, 3711 (2014)).

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Electronic and Magnetic Structure of Quantum Materials FWP#: 10027

o Distinct spectroscopic signatures are observed in the same electronic structure for the structural, magnetic and superconducting transitions in underdoped Ba1-xKxFe2As2 , establishing microscopic coexistence of the spin- density wave and superconducting phases in these materials. o Furthermore, the spin-density wave gap is observed to be suppressed with the onset of superconductivity, signaling the dynamical competition between these electronic phases.  Elucidation of the electronic reconstruction across the nematic and magnetic transitions in the NaFeAs and multilayer FeSe systems. o High quality temperature-dependent Fermi surface mappings and band dispersions are studied in this system, providing unprecedented details of the distinct electronic reconstruction across each of the structural transition and the SDW transition. o NaFeAs and multilayer FeSe exhibit different behavior in forming the orbital anisotropy across the nematic and/or magnetic transitions, suggesting intricate interplay between the orbital, lattice and magnetic degree of freedom in iron-based superconductors.  In-situ ARPES study of MBE grown FeSe films. o Monolayer and multiple layer FeSe thin films have successfully been grown by MBE, and measured by ARPES in-situ. o Gap as large as 13meV has been observed in monolayer FeSe film, which closes at 55K or above, suggesting high temperature superconductivity. o Robust quantum “shake-off” band has been observed elucidating the strong electron-phonon interaction between the FeSe film and underlying STO substrate. o Multiple electron pockets about the M point have been resolved and combined with the observed e-p coupling allowed for the development of theory to explain the enhanced Tc (J. J. Lee et al., submitted to Nature; arXiv: 1312.2633). o Large orbital anisotropy indicating nematicity has been observed in two and more layers of FeSe film, with a transition temperature as high as 200K. o Large doping difference has been observed in the monolayer film compared to double layer film, suggesting strong doping effects by the substrate, and its importance for high temperature superconductivity in this family.  Performed inductive magnetic measurements on FeSe films in search for the Meissner effect, the diamagnetic signal linked to superconductivity (Y. Cui et al., submitted to Phys. Rev. Lett).  Used monolayer FeSe as a template to study the orbital influence on the electronic structural evolution in the Fe- pnictide family of superconductors.  Using Bi2Se3 MBE thin films for 2PPE ARPES measurements to study the Dirac cone electronic structure in the unoccupied band structure.  Formed a collaborative effort with Hussain group at LBNL to pursue monolayer films of MoSe2 grown on various substrates. Have successfully produced films grown on GaAs(111) and our collaborators have demonstrated the electronic structure of monolayer MoSe2 on graphene as observed in ARPES (Y. Zhang, et al., Nature Nano 9, 111 (2014)). Supplied MoSe2 thin films to a number of groups for collaborative research.  In a collaborative effort with NREL, studied electronic structure of doped nickel-oxide for electrochromic applications and their potential for Li-air cathode applications. (F. Lin et al., ACS Appl. Mater. Inter. 5, 301 (2013), F. Lin et al., ACS Appl. Mater. Inter. 5, 8820 (2013), R. G. Moore et al. submitted to Chem. Phys. Lett).  Installed and commissioned Veeco GEN 930 Oxide MBE system at SSRL. This system will ultimately be connected to the new SSRL ARPES beamline once it is completed. o Developed SrTiO3 and BaTiO3 thin films utilizing oxygen-18 for isotopic effects in the electron-phonon coupling between FeSe monolayer films and underlying substrate. o Developing Ferroelectric films to understand interplay between interface ferroelectric transition and electronic gap in FeSe films.  Installed and commissioned ozone distillation unit connected to oxide MBE system.  Develop transport probe for in situ characterization of thin films.  Developed FeTe/Bi2Te3 interfaces for in situ ARPES where hints of new states not observed in component materials are found.  Commission the upgrade of a lab based ARPES instrumentation to include a Scienta R8000 electron analyzer  Continue to develop a novel 11eV laser source, in collaboration with Luminux Inc.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Electronic and Magnetic Structure of Quantum Materials FWP#: 10027

 Time-resolved photoemission studies of topological insulator compounds. o Electron dynamics of newly discovered 2nd unoccupied Dirac Cone (J. A. Sobota et al., PRL 111, 136802 (2013)) o Discovery of bulk and surface phonon modes in the conduction band and occupied Dirac cone. Demonstrated sub-meV energy resolution to distinguish the mode energies.  Time-Resolved Photoemission studies of CeTe3 CDW compound o tuning the pump energy into the CDW gap decreases the coherent response of the CDW amplitude mode and evidences that excitation phase space for electron-hole pair creation across the CDW gap is crucial o k-dependent analysis of coherent amplitude modes response and coherent phonon modes highlights the coupling and symmetry of charge  Time-resolved photoemission studies of monolayer and multilayer FeSe/STO

o Similarity of Se A1g mode in monolayer and multilayer samples points to interfacial phonon matching of film and substrate phonons.  Time-resolved Photoemission studies of optimally doped Bi2212 o Energy-resolved hot electron relaxation rates in the nodal region show discontinuity near 50meV, which is identified as the energy scale of the boson most strongly coupled to electronic bands. o Resolved a strongly coupled 4THz coherent phonon mode in the nodal region, which will allow tracking the electron-phonon coupling in the time domain as function of electron momentum. o Transient shift of the Fermi wavevector points to a photo-doping effect.  ARPES and time-resolved photoemission studies of the metastable phase in the CDW material TaS2 o ARPES clearly shows how the Mott gap is opening and closing for the metastable and normal state, thereby microscopically explaining the drastic resistive changes observed by transport measurements. o Time-resolved photoemission suggests that the switching into a metastable phase is driven by a transient imbalance of electron-hole pairs above a threshold excitation density.  Time-resolved photoemission studies of the surface photo voltage in GaAs o the electrostatic nature of the surface photovoltage is shown to be a valuable tool for finding and optimizing spatial and temporal overlap of pump and probe pulses. (S.-L. Yang et al., Applied Physics A, in print)  Collaboration with Y.L Chen (University of Oxford, UK): 6eV circular dichroism evidence topological nature of electronic states in the polar material BiTeCl. (Y.L. Chen et al., Nature Physics, 9, 704 (2013))  Successfully obtained 14M CPU-hours in allocations for computational simulations at NERSC  Simulation of photon spectroscopies for correlated electron systems, NERSC DOE Production Grant, 11,000,000 CPU hrs (AY 2014).  Massively parallel simulation of pump-probe time-resolved photoemission, NERSC DOE Production Grant, 3,000,000 CPU hrs (AY 2014) in collaboration with J. K. Freericks (Georgetown).  Developed a phenomenological model for the interplay between superconductivity and the pseudogap based on fluctuating, short-range charge order.  We evaluate the angle-resolved photoemission response in the anti-nodal region as a function of temperature from the pseudogap phase through the superconducting transition to low temperature approximating the influence of short-range charge order as an extra term in the electronic self-energy.  Assuming competition between superconductivity and charge order, we use a Ginzburg-Landau-like description to determine the effective strength of both the superconducting and charge order parameters as a function of temperature, reproducing the antagonistic relationship between superconductivity and the pseudogap observed in the photoemission lineshapes and spectral weight.  In addition, the model highlights the importance of bosonic mode coupling in establishing the correct “peak- dip-hump” structure of the experimental lineshapes and their evolution with temperature.  We have performed weak-coupling, multi-orbital and multi-band studies of the influence of both superconductivity and spin density waves on the evolution of the angle-resolved photoemission spectra in iron-based superconductors (M. Yi et al., Nature Comm. 5, 3711 (2014)).

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Electronic and Magnetic Structure of Quantum Materials FWP#: 10027

 The numerical calculations are based on a realistic five-orbital, five-band tight-binding model of the iron pnictide bandstructure and a simple spin fluctuation description for the effective interactions which in principle produces both spin density waves and superconductivity in simulations.  Treating superconductivity as a “locked-in” order whose strength is allowed to vary as a function of temperature, mimicking the experimental evolution of the order parameter, we self-consistently determine its influence on the spin density wave order parameter and ultimately on the photoemission response.  In agreement with experiment, we find that superconductivity and the spin density wave compete, with a reduction of the spin density order parameter and its associated photoemission gap size with the onset of superconductivity. In addition, to faithfully recreate the response, one must include an additional orbital splitting term to shift the bands which also competes with superconductivity based on our analysis.  We performed a simulation of the angle-resolved photoemission spectrum in monolayer FeSe thin films to understand the experimental observation of a robust quantum “shake-off” band in collaboration with S. Johnston (Tennessee).  We derived an expression for the effective coupling of FeSe electrons to an out-of-plane optical phonon mode in the strontium titanate (STO) substrate which is strongly peaked in the forward scattering (q=0) direction.  The simulated photoemission response closely matches the experimentally observed “shake-off” due to the strong forward scattering which has the unique capacity also to enhance the pairing and to raise the superconducting transition temperature (an analysis conducted in collaboration with D.H. Lee (Berkeley)).  We utilized determinant quantum Monte Carlo to investigate the evolution of the single-particle spectral function for the Hubbard-Holstein model and to understand the interplay between strong electron-electron and electron-phonon interactions and its signatures in photoemission.  The results show signatures of both interactions in terms of large-scale band renormalizations and the appearance of characteristic “kinks” in the dispersion. We also have observed the emergence of a dispersion to the renormalized phonon energy and a dramatic softening approaching the charge density wave phase.  The results help to further characterize the interesting emergence of a metallic phase between the two insulating phases of spin density wave driven by electron-electron interactions and charge density wave driven by electron-phonon coupling.  We have developed a determinant quantum Monte Carlo code in collaboration with S. Johnston (Tennessee) to study the multi-orbital Hubbard-Holstein model.  This code will allow us to investigate the influence of real charge transfer correlations, multi-orbital hybridization, and, most importantly, a more realistic electron-phonon coupling on the single-particle spectral function through selective tuning of coupling to different oxygen vibrations.  We have used determinant quantum Monte Carlo and small cluster exact diagonalization to investigate the “orbital loop current” proposal for the cuprate pseudogap.  We have analyzed the evolution of the orbitally projected spin magnetization and the current-current correlation function in multi-orbital Hubbard models of the cuprates.  We find no strong evidence for either the appearance of significant local moments on oxygen or correlations in the current response corresponding to those of the proposed “orbital loop currents”. This result suggests that the pseudogap in the cuprates must have a very different origin, but leaves an open question about the origin of the corresponding experimental neutron scattering observations.  We have investigated whether or not an RPA description for the spin and charge response functions can be appropriate in the Hubbard model for the cuprates and the doping range over which one finds significant effects from correlations.  Over a wide doping range, we have compared an RPA form for the response functions to those derived from determinant quantum Monte Carlo and maximum entropy analytic continuation.  Up to a fairly high doping level there remain significant differences between the RPA and full response functions, indicating the continued importance of additional vertex corrections and correlating with observations in the single-particle spectral function from photoemission as well as multi-particle probes.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Electronic and Magnetic Structure of Quantum Materials FWP#: 10027

 We have performed a “fidelity analysis” of superconductivity and “d-density wave” order in a strongly renormalized Hubbard-like model for the cuprates in collaboration with B. Laughlin (Stanford).  In mean-field theory this model possesses a phase diagram remarkably similar to that of the cuprates including a d-density wave phase in proximity to the experimentally observed pseudogap phase.  In the fidelity study performed on small clusters we observe something similar with a strong antiferromagnetic phase at half-filling and significant superconducting and d-density wave correlations up to ~25% hole-doping.  We have studied spin-orbital entanglement and fractionalization in a one-dimensional spin-orbital system (C.-C. Chen et al., arXiv:1402.3255).  We investigated the excitation spectrum using a combination of analytical techniques and numerical simulations based on cluster perturbation theory.  We observed the cross-over between fractionalized excitations and strongly entangled spin and orbital degrees of freedom as a function of orbital splitting.  We have investigated theoretical constructions for fractional Chern insulators which possess many-body interacting topologically ordered states that have potential applications in topological quantum computation.  We first developed a simple flat-band droplet construction.  We have extended initial studies in collaboration with X.L. Qi to realize an ideal model for fractional Chern

insulators that may have a possible connection to Kondo insulators and the exotic physics of SmB6.  We developed a language for non-equilibrium processes that can replace commonly used phenomenology based on the quasi-equilibrium concepts of temperature and Fermi-Dirac distributions in collaboration with J. K. Freericks (Georgetown).  Demonstrated how decay rates can be related to microscopically-derived quantities.  In electron-phonon coupled systems we showed that quasiparticle decay can be used to extract the imaginary part of the electronic self-energy and pinpoint the bosonic mode character and coupling in a quantitatively different way than that performed in equilibrium or in the frequency domain (M. Sentef et al., Phys. Rev. X 3, 041033 (2013), A. F. Kemper submitted to Phys. Rev. Lett.).  We provided new insights on properly establishing gauge invariance in simulations of time-resolved photoemission spectroscopy (arXiv: 1403.7585, collaboration with J. K. Freericks (Georgetown)).  We derived sum rules for out-of-equilibrium processes in simple systems like the Holstein model for coupling between non-interacting electronic and lattice degrees of freedom (arXiv:1403.5604, collaboration with J. K. Freericks (Georgetown)).  We developed a description for non-trivial “quantum geometry” (Berry curvature/Chern number) in single-layer graphene driven by circularly polarized light pulses based on Keldysh techniques (arXiv:1401.5103)  Treated a realistic graphene band structure, not just the Dirac electrons, subjected to a time-varying, circularly polarized electric field which breaks time-reversal invariance.  This leads to non-trivial pseudospin texture and the possibility of an interesting “quantum geometry”, including light-induced edge-states.  A similar formalism has been developed using also Floquet techniques to address “quantum geometry” effects in analogs of graphene.  We have started investigating the possibility of using light to tune the valley degeneracy in monolayer dichalcogenides like MoS2 or MoSe2.  This could have potential applications in driving a “valley Hall” effect and forms a basis for simulating “valleytronics” in this class of materials.  We have continued development of state-of-the-art charge transfer full atomic multiplet code able to calculate various spectroscopies for clusters of transition metal oxides.  Demonstrated the ability to diagonalize Hilbert spaces in excess of 1010 x 1010 elements using advanced checkerboard decomposition of matrices and the PARMETIS package with continued improvements in algorithmic performance.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Electronic and Magnetic Structure of Quantum Materials FWP#: 10027

 Developed extensions of the code to calculate resonant and non-resonant x-ray inelastic scattering response using the bi-conjugate gradient stabilized method.  We combined state-of-the-art small cluster codes with Krylov subspace-based methods for efficient evaluation of wave-function time-evolution.  The development code has been used to study the interplay between strong electronic correlations and strong electron-phonon coupling in the Hubbard-Holstein Hamiltonian.  We simulated the “melting” of a charge density wave (CDW) system in close proximity to both a spin density wave (SDW) phase and intervening metallic regime which demonstrates either partial melting for a very strong CDW or entry into the intervening metallic phase for a weak CDW with little evidence for a direct cross-over to the SDW phase. Demonstrated code performance with strongly coupled electron-phonon systems in the small polaron regime driven out of equilibrium by strong applied electric fields. Expected Progress in FY2015  We will further study the critical point and re-entrant behavior of the pseudogap in the overdoped regime of the phase diagram. o We plan to perform more careful study around the critical point in Bi2212 to establish the re-entrant behavior, focusing on aspects such as temperature dependence of the gap function, Fermi velocity, doping dependence of Fermi surface volume, next nearest neighbor hopping and bosonic mode coupling. We will search for any anomaly around the critical point, including mass divergence and scattering rate. o Other cuprate superconductor families, such as Bi2201, will be studied to reveal the universality and importance of the critical point in the cuprates. o We will fully make use of the newly installed basement laser ARPES setup with the Scienta R8000 analyzer, the 7 eV laser, and the new 11 eV laser for this study. Ultra high-energy and momentum resolution are critical to proceeding with this project. o Also, we will continue to grow cuprate samples using the floating zone method, which allows us to access wide range of doping levels with high precision. Systematic fine doping dependence study is planned to pin down the pseudogap reentrant phase boundary.  Continue to study the pseudogap electronic structure, particularly looking for direct evidence for charge modulations in the pseudogap state. o Search for the wave vector related to the pseudogap order, by focusing on Bi2201. o Full momentum dependence study across the pseudogap temperature and across Tc. o Very detailed temperature dependence study to detect subtle changes across characteristic temperature scales.  Search for pairing glue, particularly focusing on the heavily overdoped Bi2212 where pure d-wave superconductivity is expected. o Identify the bosonic mode directly related with superconductivity by studying detailed temperature and momentum dependence of the near-nodal dispersion. o Expand to the extremely overdoped regime, possibly to Tc ~ 0 K Bi2212. o Develop more accurate and robust analysis method for the self-energy. The high precision data from the planned new experimental setup allows us to discuss more details about the fine electronic structure. o Unify picture for the nodal and antinodal spectral lineshape. o Directly compare spectral features between pure superconductivity regime and previously studied pseudogap regime. Disentangle interacting phase from superconductivity in less overdoped region.  With improving sample quality, we hope to improve upon spectra quality for detailed line-shape analysis that will enable us to study issues such as kink structure pertaining to electron-phonon coupling, scattering rate, etc.

 Study the superconducting gap structure of the Ba1-xKxFe2As2 system. o In particular, the gap structure in the underdoped region will be studied in detail for signs of competition with the SDW phase, as gap nodes have been predicted by theory and observed in transport measurements. Locating these nodes will provide input for constraints on theoretical work to elucidate the superconductivity mechanism.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Electronic and Magnetic Structure of Quantum Materials FWP#: 10027

o Detailed doping dependence will be studied to see how the gap structure evolves from the underdoped region where superconductivity coexists with nematicity and SDW to the optimal region where gap has been observed to be isotropic.  We would like to study the normal state properties of various iron-based superconductors. o In particular, we would like to perform quantitative analysis of the scattering rate of each of the dxz, dyz, and dxy-dominated bands in the normal state to qualify them for the notion of quasipaticles upon the evolution from weakly correlated metal to strongly correlated insulators, in connection to resistivity measurements.

o Doping dependence in systems such as P-BaFe2As2 will be performed to locate the system in marginal Fermi liquid or Fermi liquid regime, providing an important starting point for theoretical understanding of these systems in the pre-superconducting states.  A comprehensive study of the material dependence of various parameters will be put forth over the major iron-based superconductor families o Spectroscopic parameters such as orbital-dependent renormalization factor, bandwidth, Fermi velocity, effective mass, orbital anisotropy energy scale, SDW energy scale, superconducting gap structure, scattering rate, etc, will be analyzed and extracted from available data of the major iron-based pnictide families: BaFe2As2, NaFeAs, Fe(Te/Se), FeSe film, and related to important parameters such as pnictigen/chalcogen height, Fe-As-

Fe bond angle, Tc, for understanding of potential trends in the iron-based superconductors, in an effort to shed

light on the best recipe to raise TC in these materials.  Continue to pursue efforts in monolayer FeSe superconductors. Attempt to control the electronic structure by doping, via substrate preparation and dopant, and by strain via utilizing different substrates. Continue to characterize films to fully characterize the transport properties for fundamental understanding of underlying physics. Pursue O18 isotope exchange experiments to investigate the role of substrate phonons. Supply FeSe/STO films to collaborators with more systematic investigations.  Continue to pursue efforts in monolayer MoSe2 films grown on different substrates. Understand the direct band gap electronic structure and its interaction with the underlying substrate. Supply MoSe2 films to broader range of collaborations.  Continue to produce Bi2Se3 and Bi2Te3 thin films in support of fundamental understanding of material properties and for device fabrication.  Development of preliminary oxide films focusing on cuprates for investigations of high temperature superconductivity and doped nickel-oxides for investigations of Li-O surface chemistry and their potential for Li-air cathode applications.  Continue developing ferroelectric films for interfacial control of FeSe Tc enhancement  Explore novel quantum materials with ultra-high energy and momentum resolution with the newly commissioned system.  Expand the studies of cuprate compounds in the time domain o Momentum- and energy-dependent analysis of electron and hole lifetimes o Limit excitation densities to preserve the superconducting state o Search for collective excitations of the superconducting condensate o Tune pump-photon energy to illuminate the unoccupied band structure o Continued studies of the electron momentum dependence of strongly coupled low energy phonon modes

 Exploratory studies of BCS-CDW cross-over compounds (e.g. NbSe2) in the time domain o Selective excitation of electrons across CDW bandgap using MIR pump photon energies o Observing cross-over of CDW amplitude mode into superconducting stat

 Exploratory studies of BCS superconductors (e.g. MgB2) in the time domain  Microscopic understanding of electron-boson coupling in the time domain  Search for cooperative phenomena in multiband systems (Leggett modes)

 Time-resolved photoemission studies of FeS2  Search for predicted surface state, its electron dynamics and bulk coupling to solve the long-standing puzzle of

low photovoltage in FeS2 with implications for photovoltaic and catalytic applications

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Electronic and Magnetic Structure of Quantum Materials FWP#: 10027

 Exploratory studies of the electron dynamics in the Kondo system YbRh2Si2 to find key signatures of Kondo behavior in the time domain.

 Exploratory work on ZrTe5 to prove or disprove its topological insulator character or transiently induce a topological non-trivial phase  Continued refinement of state-of-the-art quantum Monte Carlo simulations. o Investigate photoemission and two-particle quantities including optical conductivity, dynamic spin- and charge- density correlation functions, and Raman response functions. o Extend the analysis that is currently underway to multi-orbital models for the cuprates and other correlated electron materials. o Continue investigating the interplay between electron-electron and electron-phonon interactions in the Hubbard- Holstein model by extending the current studies at half-filling to a wide range of doping. o Commissioning studies of the multi-orbital Hubbard-Holstein code to benchmark code performance. o Start simulations to analyze the single- and multi-particle spectra for coupling to various oxygen phonon modes, especially the buckling and breathing modes already identified in photoemission experiments.  Continue to investigate the possible origins for the pseudogap in cuprates and its potential link to the pairing glue. o Continue performing analysis to rule-in or rule-out more exotic phases such as “orbital loops” or “d-density waves” using small cluster, determinant quantum Monte Carlo, and phenomenological studies. o Characterize the potential for charge order in simple models for the cuprates, especially in the multi-orbital Hubbard-Holstein, away from half-filling and at a characteristic wave vector qualitatively similar to that in experiment. o Fold together information from the single-particle spectrum and complimentary studies in neutron or x-ray scattering for a comprehensive view within the framework of a single simulation capable of accessing different correlation functions such as small cluster exact diagonalization or quantum Monte Carlo.  Extend the modified Krylov-based exact diagonalization approach to study time evolution of driven systems having charge, spin, orbital and lattice degrees of freedom. o We will emphasize driving and relaxation between distinct states of matter such as charge-density-wave, spin- density-wave, and metallic states. o We will use this technique in conjunction with on-going investigations using quantum Monte Carlo to characterize the nature of the emergent metallic phase and better understand the evolution of elementary excitations and charge, spin, and potentially lattice dynamics across the various phase boundaries in the Hubbard-Holstein model. o We will continue to investigate the possibility of “photoinduced” phase transitions in these highly correlated systems either through charge driving (applied fields) of direct photoexcitation.  Further refinement of time-domain Keldysh techniques. o Investigate pump-probe photoemission in the superconducting state of s-wave, phonon mediated superconductors. o Continue to develop codes for multi-particle response functions appropriate for Keldysh methods and systems out of equilibrium such as pump-probe optical conductivity and reflectivity.  Continue development of non-equilibrium solvers for dynamical mean-field theory (DMFT) in collaboration with J. K. Freericks (Georgetown). o Design and test non-equilibrium numerical renormalization group approach to enable Keldysh time-domain studies of the Hubbard model on significantly longer time-scales than currently feasible with other techniques such as continuous time Monte Carlo.  Continue development of Floquet codes to investigate “quantum geometry” in analogs of graphene with potential applications in “valleytronics”. o Refine the tight-binding description used for the band structure in materials like MoS2, MoSe2, and other monolayer dichalcogenides. o Characterize changes in the “pseudospin” texture with changes in the insulating gap structure and applied field.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Electronic and Magnetic Structure of Quantum Materials FWP#: 10027

o Investigate the possible “valley Hall effect” and applications in “valleytronics” and tuning these effects with changes in site energy and applied field.  Continue development of charge-transfer full atomic multiplet codes. o Improved usability. o Complete integration with full ab-initio back-end support for parameter-free evaluation of effective cluster parameters.

Expected Progress in FY2016  We plan to have deeper understanding of the relationship between the pseudogap, mode-coupling, superconductivity, and the resulting phase diagram. o Identify the form of the pseudogap more in detail and study its universality by material dependent study. o Develop a sophisticated phenomenological model to explain the complex doping, temperature, momentum and material dependence of the spectral lineshape by at least including the effects of the pseudogap, electron-boson coupling and superconductivity. With deeply overdoped Bi2212 samples, we anticipate the inclusion of the Van Hove singularities and bilayer splitting into a complete description of the multi-energy scale high Tc problem. o Determine the energy scales for superconductivity, pseudogap and bosonic mode coupling more quantitatively.  Search for the “pairing glue” in the cuprates by studying the “kink” features in an expanded doping, momentum, and material window. o Layer dependence: Bi2201, Bi2212, and Bi2223; Tl-based cuprates o Single layer cuprates with different optimal Tc. Comparison between Bi, Hg, and Tl based cuprates. o Understand the pairing glue, and engineer samples accordingly to yield higher Tc utilizing our basement in-situ MBE-ARPES system and SSRL BL5-2 oxide MBE system.  Utilize the availability of the new PGM grating and EPU at SSRL BL5-2 o We will be able to optimize the experimental condition for the study of LSCO. Detailed doping and temperature dependence of the gap function with high-energy resolution, particularly on deeply underdoped regime, is planned. o Other cuprate systems, such as Tl and Hg based cuprates and electron doped cuprates will be tested to establish the optimized photon energy and polarization.  Fully implement oxide thin film growth and in-situ ARPES investigation at SSRL beamline 5.  Continue to explore quantum materials in low dimensions to understand the interplay between coupling degrees of freedom and how to control them.  Develop oxide-chalcogenide heterostructures for control of interfacial enhancements of superconductivity.  Develop chalcogenide films and heterostructures to explore thermoelectric enhancements by utilizing topological character.  Continue to pursue ultra-high resolution ARPES with the upgraded laser based ARPES system.  Explore new avenues for characterization of thin films, both in-situ and ex-situ, taking advantage of the SLAC SSRL capabilities and the capabilities within the SIMES community.  tr-ARPES can be used to study the interplay of nematic, SDW and SC phases in the underdoped region, using both laser-based tr-ARPES and scattering experiments at LCLS.  Start the commissioning of tr- and spin resolved ARPES system to study magnetic materials and spin-orbital physics.  Begin to plan a possible HHG based tr-ARPES study.  MBE in-situ ARPES would be implemented to study SC in the film and interface, and provides systematic control (lattice, doping, symmetry) to study SC.  Fine doping dependence studies will be performed in various well-characterized pnictide families for a better understanding of the complex phase diagram and issues such as the existence of quantum critical points.  Fully implement oxide thin film growth and in-situ ARPES investigation at SSRL beamline V.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Electronic and Magnetic Structure of Quantum Materials FWP#: 10027

 Continue to explore quantum materials in low dimensions to understand the interplay between coupling degrees of freedom and how to control them.  Continue to pursue ultra-high resolution ARPES with the upgraded laser based ARPES system.  Continue development of advanced numerical techniques to study non-equilibrium phenomena.  Continue development of advanced numerical techniques to calculate photon-based spectroscopies in a wide variety of correlated materials, coupling ab-initio based methods with correlated model approaches.  Develop and deploy more advanced numerical techniques designed to calculate photon-based spectroscopies in a wide variety of correlated materials  Provide more direct coupling between ab initio methods and the currently deployed correlated model approaches.  Start to deploy different algorithms for treating correlated, Hubbard-like models such as cluster perturbation theory, continuous time quantum Monte Carlo, dynamical density matrix renormalization group, or dynamical mean-field theory (DMFT) and its cluster extensions.  Continue development of techniques to treat systems out of equilibrium.  Continue development of methods to treat not only the influence of strong applied fields, but also direct photoexcitation and the influence of these excitonic effects on the return to equilibrium or any photoinduced properties.  Refine studies on pump-probe spectroscopy in superconductors and other ordered states.  Continue to develop and deploy new impurity solvers for non-equilibrium dynamical mean-field theory and related Keldysh techniques.  Further refine the Floquet analysis and continue to investigate photoinduced “quantum geometry” and exotic ordered states.

Collaborations Ament, Luuk, Strategic Research at ASML, The Netherlands; Analytis, J G, UC Berkeley; Ando, Yoichi, Osaka University; Banerjee, Tamalika, University of Groningen; Baumberger, Felix, U Geneva; Bluhm, Hendrik, Lawrence Berkeley National Laboratory (LBNL); Cataudella, V., Universit`a di Napoli Federico II; Chen, Cheng-Chien, Argonne National Laboratory; Chen, Yulin, Oxford University, England; Cheng, Hai- Ping, University of Florida; Chuang, Yi-De, LBNL; Cuk, Tanja, UC Berkeley; Degiorgi, Leonardo, ETH Zurich, Switzerland; Freericks, James K., Georgetown University; Fujimori, Atsushi, University of Tokyo, Japan; Greven, Martin, University of Minnesota; Hackl, Rudi, Walther Meissner Institut, Bayerische Akademie der Wissenschaften, Germany; Hancock, Jason, University of Connecticut; He, Rui-Hua, Boston College, Massachusetts; Hemminger,John C., UC Irvine; Hill, John, Brookhaven National Laboratory; Hirschfeld, Peter, University of Florida; Hussain, Zahid, LBNL; Johnston, Steven, University of British Columbia, Canada; Kaindl, Robert A., LBNL; Kampf, Arno P., University of Augsburg; Kemper, Alexander F., LBNL; Kim, Changyoung, Yonsei University, South Korea; Kim, Young-June, University of Toronto, Canada; Krishnamurthy, H. R., Indian Institute of Science, Bangalore, India; Lee, Dung-Hai, UC Berkeley; Lipp, Magnus J.,LLNL; Liu , Amy Y., Georgetown University; Mazin, Igor I., Naval Research Laboratory; Meevasana, Worawat, Suranaree University of Technology, Thailand; Mishchenko, Andrey S, RIKEN Advanced Science Institute, Japan; Monney, Claude, Fritz-Haber-Institut, Berlin, Germany; Nagaosa, Naoto, University of Tokyo, RIKEN Advanced Science Institute, Japan; Orenstein, Joseph, LBNL; Patthey, Luc, Paul Scherrer Institut, Switzerland; Sawatzky, George A., University of British Columbia, Canada; Scalapino, Douglas J., UC Santa Barbara; Scalettar, Richard T., UC Davis; Schmitt, Thorsten, Paul Scherrer Institute, Switzerland; Schoenlein, Robert W., LBNL; Shastry, B. Sriram, UC Santa Cruz; Shen, Kyle M., Cornell University; Singh, Rajiv R. P., UC Davis; Stock, Chris, NIST Center for Neutron Research, Indiana University Cyclotron Facility; Strocov, Vladimir N., Paul Scherrer Institute, Switzerland; Thomale, Ronny, University of Wurzburg, Germany; Tohyama, Takami, Kyoto University; Uchida, Shin-Ichi, University of

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Electronic and Magnetic Structure of Quantum Materials FWP#: 10027

Tokyo, Japan; van den Brink, Jeroen, IFW Dresden, Germany; van der Marel, Dirk, Université de Genève, Switzerland; van Veenendaal, Michel, Northern Illinois University, Argonne National Laboratory; Vernay, Francois, Université de Perpignan, France; Vishik, Inna, MIT; Yang, WanLi, LBNL; Zaanen, Jan, University of Leiden, The Netherlands .

Publications for FY13 & FY14 (Oct 1st 2012 to date) Peer-Reviewed Journal Articles 1. Competition Between Antiferromagnetic and Charge-Density-Wave Order in the Half-Filled Hubbard-Holstein Model, E. A. Nowadnick, S. Johnston, B. Moritz, R. T. Scalettar, and T. P. Devereaux, Phys. Rev. Lett. 109,246404 (2012). 2. Phase competition in trisected superconducting dome, I. M. Vishik, M. Hashimoto, R.-H. He, W.-S. Lee, F. Schmitt, D. Lu, R. G. Moore, C. Zhang, W. Meevasana, T. Sasagawa, S. Uchida, K. Fujita, S. Ishida, M. Ishikado, Y. Yoshida, H. Eisaki, Z. Hussain, T. P. Devereaux, and Z.-X. Shen, Proc. Nat. Acad. Sciences 109,18332 (2012). 3. Pulsed high harmonic generation of light due to pumped Bloch oscillations in noninteracting metals, J. K. Freericks, A. Y. Liu, A. F. Kemper, and T. P. Devereaux, Physica Scripta T 151, 014062 (2012) 4. Quantum Dynamics of the Hubbard-Holstein Model in Equilibrium and Nonequilibrium: Application to Pump-Probe Phenomena, G. De Filippis, V. Cataudella, E. A. Nowadnick, T. P. Devereaux, A. S. Mishchenko, and N. Nagaosa, Phys. Rev. Lett. 109,176402 (2012). 5. Quasiparticle interference and the interplay between superconductivity and density wave order in the cuprates, E. A. Nowadnick, B. Moritz, and T. P. Devereaux, Phys. Rev. B 86,134509 (2012). 6. Examining Electron-Boson Coupling Using Time-Resolved Spectroscopy, M. Sentef, A. F. Kemper, B. Moritz, J. K. Freericks, Z.-X. Shen, and T. P. Devereaux, Phys. Rev. X 3, 041033 (2013). 7. Tunneling Spectroscopy for Probing Orbital Anisotropy in Iron Pnictides, N. Plonka, A. F. Kemper, S. Graser, A. P. Kampf, and T. P. Devereaux, Phys. Rev. B 88, 174518 (2013). 8. Direct Optical Coupling to an Unoccupied Dirac Surface State in the Topological Insulator Bi2Se3, J. A. Sobota, S. Yang, A. F. Kemper, J. J. Lee, F. T. Schmitt, W. Li, R. G. Moore, J. G. Analytis, I. R. Fisher, P. S. Kirchmann, T. P. Devereaux, and Z.-X. Shen, Phys. Rev. Lett. 111, 136802 (2013). 9. Electron-Mediated Relaxation Following Ultrafast Optical Pumping of Strongly Correlated Materials: Model Evidence of a Correlation-Tuned Crossover Between Thermal and Nonthermal States, B. Moritz, A. F. Kemper, M. Sentef, T. P. Devereaux, and J. K. Freericks, Phys. Rev. Lett. 111, 077401 (2013). 10. Determinant Quantum Monte Carlo Study of the Two-Dimensional Single-Band Hubbard-Holstein Model, S. Johnston, E. A. Nowadnick, Y. F. Kung, B. Moritz, R. T. Scalettar, and T. P. Devereaux, Phys. Rev. B 87, 235133 (2013). [Editors Suggestion]. 11. Hot Electron Transport in a Strongly Correlated Transition Metal Oxide, Kumari Gaurav Rana, Takeaki Yajima, Subir Parui, Alexander F. Kemper, Thomas P. Devereaux, Yasuyuki Hikita, Harold Y. Hwang, and Tamalika Banerjee, Scientific Reports 3, 1274 (2013). 12. Theoretical Description of High-Order Harmonic Generation in Solids, A. F. Kemper, B. Moritz, J.K. Freericks, and T. P. Devereaux, New J. Phys. 15, 023003 (2013). 13. Measurement of Coherent Polarons in the Strongly Coupled Antiferromagnetically Ordered Iron- Chalcogenide Fe1.02Te using Angle-Resolved Photoemission Spectroscopy, Z. K. Liu, R.-H. He, D. H. Lu, M. Yi, Y. L. Chen, M. Hashimoto, R. G. Moore, S.-K. Mo, J. Hu, T. J. Liu, Z. Q. Mao, T. P. Devereaux, Z. Hussain, and Z.-X. Shen, Phys. Rev. Lett. 110, 037003 (2013). 14. Alternative Route to Charge Density Wave Formation in Multiband Systems, H.-M. Eiter, M. Lavagnini, R. Hackl, E.A. Nowadnick, A.F. Kemper, T.P. Devereaux, J.-H. Chu, J. G. Analytis, I. R. Fisher, and L. Degiorgi, Proc. Nat. Acad. Sciences 110, 64 (2013). 15. Measurement of Coherent Polarons in the Strongly Coupled Antiferromagnetically Ordered Iron- Chalcogenide Fe1.02Te using Angle-Resolved Photoemission Spectroscopy. Z. K. Liu, R.-H. He, D.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Electronic and Magnetic Structure of Quantum Materials FWP#: 10027

H. Lu, M. Yi, Y. L. Chen, M. Hashimoto, R. G. Moore, S.-K. Mo, E. A. Nowadnick, J. Hu, T. J. Liu, Z. Q. Mao, T. P. Devereaux, Z. Hussain, and Z.-X. Shen. Physical Review Letters, 110/3, 037003 (Jan. 18, 2013). 16. Observation of Temperature-Induced Crossover to an Orbital-Selective Mott Phase in AxFe2-ySe2 (A=K, Rb) Superconductors. M. Yi, D. H. Lu, R. Yu, S. C. Riggs, J.-H. Chu, B. Lv, Z. K. Liu, M. Lu, Y.-T. Cui, M. Hashimoto, S.-K. Mo, Z. Hussain, C. W. Chu, I. R. Fisher, Q. Si, Z.-X. Shen. Physical Review Letters, 110/6, 067003 (Feb. 5, 2013). 17. Formation of Heavy d-electron quasiparticles in Sr3Ru2O7. M.P. Allan, A. Tamai, E. Rozbicki, M.H. Fischer, J. Voss, P.D.C. King, W. Meevasana, S. Thirupathaiah, E. Rienks, J. Fink, D.A. Tennant, R.S. Perry, J.F. Mercure, M.A. Wang, Jinho Lee, C.J. Fennie, E-A. Kim, M.J. Lawler, K.M. Shen, A.P. Mackenzie, Z-X Shen, F. Baumberger. New Journal of Physics, 15, 063029 (June 20, 2013). 18. Electronic structure of the metallic antiferromagnet PdCrO2 measured by angle-resolved photoemission spectroscopy. J.A. Sobota; K. Kim; H. Takatsu; M. Hashimoto; S.K. Mo; Z. Hussain; T. Oguchi; T. Shishidou; Y. Maeno; B.I. Min; Z.X. Shen. Physical Review B, V88/12, 125109 (Sept. 5, 2013). 19. Direct Optical Coupling to an Unoccupied Dirac Surface State in the Topological Insulator Bi2Se3. J.A. Sobota, S.-L. Yang, A.F. Kemper, J.J. Lee, F.T. Schmitt, W. Li, R.G. Moore, J.G. Analytis, I.R. Fisher, P.S. Kirchmann, T.P. Devereaux, and Z.X. Shen. Physical Review Letters, V111/13, 136802 (Sept. 24, 2013). 20. Discovery of a Single Topological Dirac Fermion in the Strong Inversion Asymmetric Compound BiTeCl. Y.L. Chen, M. Kanou, Z.K. Liu, H.J. Zhang, J.A. Sobota, D. Leuenberger, S.K. Mo, B. Zhou, S.-L. Yang, P.S. Kirchmann, D.H. Lu, R.G. Moore, Z. Hussain, Z.X. Shen, X.L. Qi, and T. Sasagawa. Nature Physics, 9, 704 (2013). 21. Direct observation of the transition from indirect to direct bandgap in atomically tin epitaxial MoSe2. Y. Zhang, T.R. Chang, B. Zhou, Y.T. Cui, H. Yan, Z.K. Liu, F. Schmitt, J.J. Lee, R.G. Moore, Y.L. Chen, H. Lin, H.T. Jeng, S-K Mo, Z. Hussain, A. Bansil, and Z.X. Shen. Nature NanoTechnology, 9, 111 (2014). 22. Discovery of a Three-Dimensional Topological Dirac Semimetal, Na3Bi. Z.K. Liu, B. Zhou, Y. Zhang, Z.J. Wang, H.M. Weng, D. Prabhakaran, S.K. Mo. Z.X. Shen, Z. Fang, X. Dai, Z. Hussain, Y.L. Chen. Science 343, 864 (2014). 23. Charge-orbital-lattice coupling effects in the dd excitation profile of one-dimensional cuprates. J.J. Lee, B. Moritz, W.S. Lee, M. Yi, CJ Jia, A.P. Sorini, K. Kudo, Y. Koike, K.Z. Zhou, C. Monney, V. Strocov, L. Patthey, T. Schmitt, T.P. Devereaux, Z.X. Shen. Phys. Rev. B 89, 041101(2014). 24. Superconducting graphene sheets enabled by phonon-mediated interband interactions. S.-L.Yang, J.A. Sobota, C.A. Howard, C.J. Pickard, M. Hashimoto, D.H. Lu, S.-K. Mo, P.S. Kirchmann, and Z.X. Shen. Nature Communications, 5, 3493 (2014). 25. Dynamic competition between spin-density wave order and superconductivity in underdoped Ba1- xKxFe2As2. M. Yi, Y. Zhang, Z.K. Liu, X. Ding, J-H Chu, A.F. Kemper, N. Plonka, B. Moritz, M. Hashimoto, S-K Mo, Z. Hussain, T.P. Devereaux, I.R. Fisher, H.H. Wen, Z.X. Shen, D.H Lu. Nature Communications, V5 (April 25, 2014). 26. A Stable Three-dimensional Topological Dirac Semimetal Cd3As2. Z.K. Liu, J. Jiang, B. Zhou, Z.J. Wang, Y. Zhang, H.M. Weng, D. Prabhakaran, S.-K. Mo, H. Peng, P. Dudin, T. Kim, M. Hoesch, Z. Fang, X. Dai, Z.X. Shen, D.L. Feng, Z. Hussain, and Y.L. Chen. Accepted for publication by Nature Materials. 27. Nonequilibrium “Melting” of a Charge Density Wave Insulator Via an Ultrafast Laser Pulse, Wen Shen, Yizhi Ge, A. Y. Liu, H. R. Krishnamurthy, T. P. Devereaux, and J. K. Freericks, Phys. Rev. Lett. 112, 176404 (2014). 28. Gauge invariance in the theoretical description of time-resolved angle-resolved pump/probe photoemission spectroscopy, J. K. Freericks, H. R. Krishnamurthy, M. Sentef, and T.P. Devereaux, arXiv: 1403.7585. 29. Nonequilibrium sum rules for the Holstein model, J. K. Freericks, Khadijeh Naja, A. F. Kemper, and T. P. Devereaux, arXiv:1403.5604.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Electronic and Magnetic Structure of Quantum Materials FWP#: 10027

30. Local Spectral Inversion and Bosonic Extraction of the Archetypal Elemental Superconductor with S-Vacuum-S Tunneling Spectroscopy, F.C. Niestemski, S. Johnston, A.W. Contryman, C.D. Camp, T.P. Devereaux, and H.C. Manoharan, arXiv:1211.2244, submitted to Phys. Rev. Lett. 31. Energy Gaps in High-Transition Temperature Cuprate Superconductors, M. Hashimoto, I. M. Vishik, R.-H. He, T. P. Devereaux, and Z.-X. Shen, submitted to Nature Physics. 32. Effect of Dynamical Spectral Weight Redistribution on Effective Interactions in Time-resolved Spectroscopy, A.F. Kemper, M.A. Sentef, B. Moritz, J.K. Freericks, T.P. Devereaux, arXiv:1403.5245, submitted to Phys. Rev. Lett. 33. Direct Observation of Bulk Charge Modulations in Optimally-Doped Bi1.5Pb0.6Sr1.54CaCu2O8+δ, M. Hashimoto, G. Ghiringhelli, W.-S. Lee, G. Dellea, A. Amorese, C. Mazzoli, K. Kummer, N. B. Brookes, B. Moritz, Y. Yoshida, H. Eisaki, Z. Hussain, T. P. Devereaux, Z.-X. Shen, L. Braicovich, arXiv:1403.0061, submitted to Nature Materials. 34. Ubiquitous Antinodal Quasiparticles in Bi-2212, I. M. Vishik, Makoto Hashimoto, W. S. Lee, K. Tanaka, T. Sasagawa, S. Uchida, K. Fujita, S. Ishida, Z. Hussain, T. P. Devereaux, and Z. X. Shen, submitted to Phys. Rev. Lett.. 35. Ultrafast Electron Dynamics in the Topological Insulator Bi2Se3 Studied by Time-Resolved Photoemission Spectroscopy, Jonathan A. Sobota, Shuolong Yang, Dominik Leuenberger, Alexander F. Kemper, James G. Analytis, Ian R. Fisher, Patrick S. Kirchmann, Thomas P. Devereaux, Zhi-Xun Shen, arXiv:1401.3078, to appear in Journal of Electron Spectroscopy & Related Phenomena. 36. Fractionalization, Entanglement, and Separation: Understanding the Collective Excitations in a Spin-Orbital Chain, Cheng-Chien Chen, Michel van Veenendaal, Thomas P. Devereaux, Krzysztof Wohlfeld, arXiv:1402.3255, submitted to Phys. Rev. Lett. 37. Theory of Pump-Probe Photoemission in Graphene and the Generation of Light-Induced Haldane Multilayers, M. Sentef, M. Claassen, A. F. Kemper, B. Moritz, T. Oka, J. K. Freericks, and T. P. Devereaux, arXiv:1401.5103, under review at Nature Communications. 38. Angle Resolved Photoemission Spectroscopy Study of HgBa2CuO4+ , I. M. Vishik, Neven Barišić, Yuan Li, Guichuan Yu, Xudong Zhao, W. S. Lee, W. Meevasana, T. P. Devereaux, Martin Greven, and Z. X. Shen, arXiv:1402.2215, to appear in Phys. Rev. B. 39. Exact Solution for High Harmonic Generation and the Response to an AC Driving Field for a Charge Density Wave Insulator, W. Shen, T. P. Devereaux, and J. K. Freericks, arXiv:1309.3574, submitted to Phys. Rev. B 40. Exact Solution for Bloch oscillations of a Simple Charge-Density-Wave Insulator, W. Shen, T. P. Devereaux, and J. K. Freericks, arXiv:1308.6060, submitted to Phys. Rev. B. 41. Interface Induced Ferroelectric Transition near the Gap Opening Temperature in Monolayer FeSe Film Grown on Nb-doped SrTiO3 Substrate, Y.-T. Cui, J. J. Lee, F. T. Schmitt, R. G. Moore, W. Li, M. Yi, Z. Liu, M. Hashimoto, Y. Zhang, D. Lu, T. P. Devereaux, D.-H. Lee, and Z.-X. Shen, submitted to Phys. Rev. Lett. 42. Evidence for Strong Cross-Interface Electron-Phonon Coupling in Monolayer FeSe on SrTiO3, J. J. Lee, F. T. Schmitt, R. G. Moore, Y. T. Cui, W. Li, M. Yi, Z. K. Liu, M. Hashimoto, Y. Zhang, D. H. Lu, T. P. Devereaux, D. -H. Lee, and Z.-X. Shen, submitted to Nature. 43. Direct Spectroscopic Evidence for Phase Competition Between the Pseudogap and Superconductivity in Bi2Sr2CaCu2O8+δ, M. Hashimoto, E. A. Nowadnick, R.-H. He, I. M. Vishik, B. Moritz, Y. He, K. Tanaka, R. G. Moore, D. H. Lu, Y. Yoshida, M. Ishikado, K. Fujita, S. Ishida, S. Uchida, H. Eisaki, Z. Hussain, T. P. Devereaux, and Z.-X. Shen, submitted to Nature Materials. 44. Beyond Planck-Einstein Quanta: Amplitude driven Quantum Excitation, Wen Shen, T. P. Devereaux, and J. K. Freericks, arXiv:1309.2723, submitted to Nature Communications.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Correlated Materials - Synthesis and Physical Properties FWP#: 10028

Correlated Materials – Synthesis and Physical Properties Principal Investigator(s): Ian Fisher, Theodore Geballe, Aharon Kapitulnik, Steven Kivelson & Kathryn Moler Postdoctoral Scholars and Graduate Students:, Nicholas Breznay, Sudi Chen, Weejee Cho, Jiun-Haw Chu, Merav Dolev, Alan Fang, Paula Giraldo-Gallo, Alex Hristov, George Karakonstantakis, Hsueh-Hui Kuo, Tom Lippman, Ming Lu, Laimei Nie, Hilary Noad, Katja Nowack, Scott Riggs, Aaron Rosenberg, Elizabeth Schemm, M. Shapiro, Eric Spanton, Yihua Wang and Qi Yang

Overview The overarching goal of our research is to understand, and ultimately control, emergent behavior in strongly correlated quantum materials. This broad class of materials holds promise for future applications directly relevant to energy security, affecting technologies from energy distribution, to improved power electronics, to more efficient computing. There are, however, many deep intellectual questions that need to be addressed in order to realize this potential. There are also many opportunities for the development of novel materials with improved properties. The intellectual focus of this FWP sits at the intersection of these challenges and opportunities. Our research combines synthesis, measurement and theory to coherently address questions at the heart of these issues. We use cutting edge, often unique, experimental probes to uncover novel forms of electronic order in a variety of complex materials. Our theoretical work provides a framework to understand the rich variety of possible ordered states, and guides our ongoing measurements and synthesis efforts. Big questions that we collectively address include; what are the rules and organizing principles governing emergent behavior in quantum materials? What is the nature of the coexisting and competing phases in high temperature superconductors, and how do they determine/limit the maximum critical temperature? What ordered states arise in oxide systems with strong spin-orbit coupling, both in bulk materials and at interfaces? And finally, how does quenched disorder affect quantum criticality and inhomogeneous electronic states in strongly correlated materials? Our research addresses these challenging questions in the context of a range of complex quantum materials.

Progress in FY2014  Divergent nematic susceptibility of an iron arsenide superconductor revealed via differential elastoresistance measurements, (Phys. Rev. B 88, 085113 (2013); Editors Suggestion). We have developed a novel technique that reveals the nematic susceptibility of materials via differential elastoresistance measurements. In this paper we provide the formal framework to describe and understand the elastoresistance of metals, and describe the connection between differential elastoresistance and the nematic susceptibility. Results are presented for a representative underdoped iron arsenide superconductor, revealing that the nematic susceptibility diverges towards the structural phase transition following a Curie-weiss temperature dependence. This behavior directly reveals that the structural phase transition is driven by electronic nematic order. This work was highlighted in the Journal Club for Condensed Matter Physics (“Settling the Chicken and Egg question in iron based superconductors”;http://www.condmatjournalclub.org/?p=2247.).

 Quantum criticality in BaFe2(As1-xPx)2, (Nature Physics 10, 194–197 (2014)). Quantum critical behavior was observed near optimal doping in the representative Fe-based superconductor BaFe2(As1-xPx)2 via measurement of the power law behavior of the electrical resistivity. In collaboration with scientists from the National High Magnetic Field Laboratory, pulsed magnetic fields up to 65 T, and DC fields up to 45T, were used to suppress the superconducting ground state, revealing the normal state transport properties. Close to optimal doping, at high temperatures non Fermi-liquid power laws were observed. For the overdoped compositions, the resistivity recovers a T2 Fermi liquid behavior at low T. The cross over temperature extrapolates to zero close to optimal doping, while the T2 coefficient diverges similar to the effective mass, both consistent with a standard Hertz-Millis description of quantum criticality. These measurements establish that the physics of quantum criticality is likely important in determining the physical properties of the Fe pnictides close to optimal doping, possibly including the occurrence of high-temperature superconductivity.  Effect of disorder on the resistivity anisotropy near the electronic nematic phase transition in pure and electron-doped BaFe2As2, (arXiv:1311.0933) We show that the strain-induced resistivity anisotropy in the tetragonal state of the representative underdoped Fe-arsenides BaFe2As2, Ba(Fe1−xCox)2As2 and Ba(Fe1−xNix)2As2 is independent of disorder over a wide range of defect and impurity concentrations. This result demonstrates that the anisotropy in the in-plane resistivity in the paramagnetic orthorhombic state of this material is not due to elastic scattering from anisotropic defects, and is most easily understood in terms of an intrinsic anisotropy in the electronic structure.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Correlated Materials - Synthesis and Physical Properties FWP#: 10028

 Evidence of Chiral Order in the Charge-Ordered Phase of Superconducting La1.875Ba0.125CuO4 Single Crystals Using Polar Kerr-Effect Measurements, (Phys. Rev. Lett 112, 047003 (2014)) High resolution polar Kerr effect (PKE) measurements were performed on La1.875Ba0.125CuO4 single crystals revealing that a finite Kerr signal is measured below an onset temperature-T_K that coincides with charge ordering transition temperature TCO. We further show that the sign of the Kerr signal cannot be trained with magnetic field, is found to be the same of opposite sides of the same crystal, and is odd with respect to strain in the diagonal direction of the unit cell. These observations are consistent with a chiral order above Tc for La1.875Ba0.125CuO4; similarities to other cuprates suggest that it is a universal property in the pseudogap regime.

 Observation of Broken Time-Reversal Symmetry in the B Phase of the Heavy Fermion Superconductor UPt3, (Accepted for publication in Science, (2014)). The symmetry properties of the order parameter are the principal means by which different phases in unconventional superconductors are characterized. In the case of the heavy-fermion superconductor UPt3, a key step toward determining the order parameter involves resolving the question of whether its superconducting phases preserve or break time-reversal symmetry (TRS). We tested for an asymmetry between the indices of refraction of left and right circularly polarized light reflected from a single crystal of UPt3 at normal incidence. This so-called polar Kerr effect is direct evidence for broken TRS, and in our experiments appears only below the transition to the lower temperature superconducting phase. The temperature dependence of the observed Kerr effect is consistent with proportionality to the product of the two components of the order parameter.  Pulsed Laser Deposition of High-Quality Thin Films of the Insulating Ferromagnet EuS, (Appl. Phys. Lett. 104, 082402 (2014)) High-quality thin films of the ferromagnetic-insulator europium(II) sulfide (EuS) were fabricated by pulsed laser deposition on Al2O3 (0001) and Si (100) substrates. A single orientation was obtained with the [100] planes parallel to the substrates, with atomic-scale smoothness indicates a near-ideal surface topography. The films exhibit uniform ferromagnetism below 15.9 K, with a substantial component of the magnetization perpendicular to the plane of the films. Optimization of the growth condition also yielded truly insulating films with immeasurably large resistance. This combination of magnetic and electric properties open the gate for novel devices that require a true ferromagnetic insulator.  Quenched disorder and vestigial nematicity in the pseudo-gap regime of the cuprates (arrXiv:1311.5580) We have carried out a theoretical analysis of the Landau-Ginzburg-Wilson effective field theory of a classical incommensurate CDW in the presence of weak quenched disorder. While the possibility a sharp phase transition and long-range CDW order are precluded in such systems, we show that any discrete symmetry breaking aspect of the charge order -- nematicity in the case of the unidirectional (stripe) CDW we consider explicitly -- generically survives up to a non-zero critical disorder strength. Such "vestigial order", which is subject to unambiguous macroscopic detection, can serve as an avatar of what would be CDW order in the ideal, zero disorder limit. Various recent experiments in the pseudo-gap regime of the hole-doped cuprate high-temperature superconductors are readily interpreted in light of these results.

 Evidence from tunneling spectroscopy for a quasi-one dimensional origin of superconductivity in Sr2RuO4

(Phys. Rev. B 88, 134521 (2013).) To establish the mechanism of unconventional superconductivity in Sr2RuO4, a

prerequisite is direct information concerning the momentum-space structure of the energy gaps Δi(k), and in particular whether the pairing strength is stronger ("dominant") on the quasi-1D (α and β) or on the quasi-2D (γ) Fermi surfaces. We present scanning tunneling microscopy (STM) measurements of the density-of-states spectra in the superconducting

state of Sr2RuO4 for 0.1Tc

2Δ≈5Tc along with a spectral shape indicative of line nodes is consistent, within a weak-coupling model, with magnetically mediated odd-parity superconductivity generated by dominant, near-nodal Cooper pairing on the α and β bands.

 Band structure effects on superconductivity in Hubbard models, (Phys. Rev. B 88, 64505 (2013).) We study the influence of the band structure on the symmetry and superconducting transition temperature in the (solvable) weak- coupling limit of the repulsive Hubbard model. Among other results we find: 1) As a function of increasing nematicity, starting from the square lattice (zero nematicity) limit where nodal d-wave state is strongly preferred, there is a smooth evolution to the quasi-1D limit, where a striking near-degeneracy is found between a p-wave- and a d-wave-type paired states with accidental nodes on the quasi-one-dimensional Fermi surfaces---a situation which may be relevant to the Bechgaard salts. 2) In a bilayer system, we find a phase transition as a function of increasing bilayer coupling from a d-

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Correlated Materials - Synthesis and Physical Properties FWP#: 10028

wave to an s± -wave state reminiscent of the iron-based superconductors. 3) When an antinodal gap is produced by charge-density-wave order, not only is the pairing scale reduced, but the symmetry of the pairs switches from d_(x2-y2) to d_{xy}; in the context of the cuprates, this suggests that were the pseudo-gap entirely due to a competing order, this would likely cause a corresponding symmetry change of the superconducting order (which is not seen in experiment).

 Locally enhanced conductivity due to the tetragonal domain structure in LaAlO3/SrTiO3 heterointerfaces revealed via scanning SQUID microscopy, (Nature Materials 12, 1091 (2013)). The ability to control materials properties through interface engineering is demonstrated by the appearance of conductivity at the interface of certain insulators, most famously the {001} interface of the band insulators LaAlO3 (LAO) and TiO2-terminated SrTiO3. Transport and other measurements in this system show a plethora of diverse physical phenomena. To better understand the interface conductivity, we used scanning superconducting quantum interference device microscopy to image the magnetic field locally generated by current in an interface. At low temperature, we found that the current flowed in conductive narrow paths oriented along the crystallographic axes, embedded in a less conductive background. The configuration of these paths changed on thermal cycling above the STO cubic-to-tetragonal structural transition temperature, implying that the local conductivity is strongly modified by the STO tetragonal domain structure. The interplay between substrate domains and the interface provides an additional mechanism for understanding and controlling the behaviour of heterostructures. (Nature Materials highlighted this article with an accompanying News and Views article, “Oxide interfaces: Streaks of conduction” by A. Brinkman.)  Images of edge current in InAs/GaSb quantum wells (arXiv:1401.1531) Quantum spin Hall devices with edges much longer than several microns do not display ballistic transport: that is, their measured conductances are much less than the expected value of $e^2/h$ per edge. The question of what causes the observed dissipation is important both for fundamental understanding and for the possibility of future spintronics applications. By imaging 2D current flow in InAs/GaSb quantum wells with long edges, we observed edge currents, and, importantly, were able to determine an effective edge resistance, which is not possible from transport measurements alone in the presence of bulk conductance. Surprisingly, although the measured resistance is not in a ballistic regime, the effective edge resistance is independent of temperature up to 30 K within experimental resolution. These results are inconsistent with known candidate scattering mechanisms.

Expected Progress in FY2015

 Nematic component to the Hidden Order phase of URu2Si2.

The nature of the Hidden Order phase in URu2Si2 has been a mystery for over 30 years. We are using measurements of the differential elastoresistance to probe the nematic susceptibility, revealing that the fluctuations associated with the 17K phase transition have a nematic component. Approaching the phase transition from above, the nematic susceptibility abruptly changes sign, indicating that while the Hidden Order phase has a nematic component, it breaks additional symmetries. Taken together these data demonstrate that the Hidden Order phase has a multi-component order parameter coupling quadratically to strain. These results put tight constraints on proposed theories of the Hidden Order phase. These initial results are currently being written up. Ongoing experiments will examine the physical origin of the induced resistivity anisotropy via similar measurements of dilute alloys Th1-xUxRu2Si2.  Elastoresistance measurements of HTSC cuprates and Fe-pnictides We have just begun a series of elastoresistance measurements of single crystals of YBCO with the aim of addressing the presence and nature of subtle electronic phase transitions in the underdoped regime. In addition, we have also begun a program to grow single crystals of LSCO and LBCO with similar aims. Finally, we will extend our original measurements of Fe pnictides to explore the behavior of the nematic susceptibility near optimal doping for a variety of related compounds and compositions, with the general aim of establishing whether the divergent nematic susceptibility observed for electron-doped compounds is a ubiquitous feature of the material.  Enhancement of superconducting pairing near a nematic quantum critical point. We are finishing a new study in which we consider a low Tc metallic superconductor weakly coupled to the soft fluctuations associated with proximity to a nematic quantum critical point (NQCP). We show that: 1) a BCS-Eliashberg

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Correlated Materials - Synthesis and Physical Properties FWP#: 10028

treatment remains valid outside of a parametrically narrow interval about the NQCP; 2) the symmetry of the superconducting state (d-wave, s-wave, p-wave) is typically determined by the non-critical interactions, but Tc is strongly enhanced upon approach to the NQCP both from the nematic and the isotropic sides; 3) in the “weakly enhanced” regime not too close to the NQCP (where the critical contribution to the dimensionless coupling parameter, λ, is subdominant) the form of the gap function (its dependence on position along the Fermi surface) is determined by the non-critical interactions, but in the “strongly enhanced” regime closer to criticality, the gap shape is determined by the critical interactions, and can be highly anomalous. For example, for d-wave pairing on a cuprate-like Fermi surface, the gap becomes increasingly sharply peaked at the antinodal extremum of the Fermi surface the closer one approaches to the NQCP.

 Quantum Oscillaitons in the presence of CDW order with short correlation lengths There has been intense interested generated by the observation of quantum oscillations in the cuprates with a period corresponding to a small Fermi pocket – much smaller than that obtained from band-structure caclculations or to be consistent with Luttinger’s theorem. This is generally accepted as evidence that some sort of Fermi surface reconstruction has occurred associated with a state of spontaneously broken translational symmetry – i.e. with density wave order. However, while evidence of short-range charge density wave order has emerged from diffraction studies, the correlation lengths never exceed 100A in-plane and one lattice constant in the interplane direction. These correlation lengths are shorter than (although not much shorter than) the inferred radius of the electron orbits in the fields at which sharp quantum oscillations are observed. In this context, it is important to address the conceptual question – how long must the correlation length of CDW order be to produce well defined quantum oscillations , and what experimentally accessible features of the quantum oscillations depend on that correlation length?  Search for Broken Time-Reversal Symmetry in Heavy Fermion Superconductors The symmetry properties of the order parameter are the principal means by which different phases in unconventional superconductors are characterized. Following our work on UPt3, we want to search for a pattern of time-reversal symmetry breaking within heavy Fermion systems. The method we plan to use is high resolution Kerr effect, measured using a home-invented Sagnac interferometer. An important method that we plan to implement at that time is the measurement of Kerr effect in the presence of uniaxial strain. This will be done in collaboration with the group of Ian Fisher.  Scanning Tunneling Microscopy and Spectroscopy of Topological Superconductors We plan to use our recently acquired STM system for the study of the superconducting state of several topological superconductors. First is the (p+ip)-Sr2RuO4 system. Then, we plan to study half-Heusler alloys such as YPtBi, LuPtBi, and LaPtBi, all with Tc in the range of 1K. These materials should posses interesting properties near edges, defects, and vortex cores when magnetic field is applied. The addition of two K-cells to our STM’s preparation chamber will allow us to introduce impurities, as well as deposit epitaxially a small number of layers to observe the effect of this overlayers on superconductivity.  The effect of strain and structure on conductivity in complex oxide interfaces. In FY14 we showed that tetragonal domain structure affects the conductivity in LAO/STO. In FY15 we will seek to understand the microscopic and structural origins of this phenomenon by making similar measurements with tunable strain, combined with x-ray-based structural analysis.  Persistent currents in Quantum Spin Hall (QSH) systems. The quantum spin Hall (QSH) state is characterized by conducting edge channels, which are topologically protected from backscattering in ideal materials. Experimentalists demonstrated that QSH is realized in HgTe quantum wells and in InAs/GaSb quantum wells, but the ideal quantized conductance only occurs in sufficiently small samples. It is not known what breaks the topological protection, or what effect these scatterers might have on other topological phenomena. In FY14 we found that the phenomenology of the conductivity disagrees with known models of the scattering. In FY15 we will measure the thermodynamic circulating current in dots and antidots, called “persistent currents”, as a contactless method to probe edge states. The dot configuration will enable us to confirm whether the persistent current truly flows only on the edge of the material – if so, it will behave like a persistent current in a ring; i.e., its magnitude will be periodic in the magnetic flux, with a periodicity equal to one flux quantum. Detailed measurements will help identify the scattering mechanisms, and will lay the ground for studies of QSH/superconductor hybrid structures, the leading candidate for heterostructure engineering of exotic topological superconductors.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Correlated Materials - Synthesis and Physical Properties FWP#: 10028

Expected Progress in FY2016  Elastoresistance measurements of strongly correlated materials We will continue our investigation of the elastoresistance of several families of strongly correlated materials. In particular, we will explore ways that the elastotransport properties can probe other subtle forms of electronic order, including gyrotropic order. We will also seek new materials that reveal electronic nematic phases, the study of which might shed light on the significance of nematic fluctuations and nematic quantum criticality in the Fe pnictides and cuprate HTSCs.  Scanning Tunneling Microscopy and Spectroscopy in the presence of external perturbations. In our future plans we devote high priority to develop a sample holder to our Low-T/high-field UHV STM system in which strain can be applied in-situ. We also plan to implement a light source into the STM system to be able to do Photo-induced spectroscopy.  Vestigial Order in Strongly Correlated Electron Systems When there is a sequence of transitions separating an ordered (broken symmetry) state from a disordered (symmetric) state, intermediate phases that restore some but not all of the symmetries broken in the fully ordered state can be said to have ``vestigial order.'' The most familiar example from classical physics is the hexatic phase in the theory of 2D melting. We discuss general aspects of the theory of vestigial order and as an explicit example, we analyze a solvable O(N) quantum rotor model of the formation of an electron-nematic phase through the partial melting of a unidirectional (striped) antiferromagnet by thermal or quantum fluctuations, or as a function of increasing quenched disorder. We comment on the relevance of these considerations to the formation of nematic phases in the cuprates, Fe-pnictides, Sr3Ru2O7, and quantum Hall systems, as well as for possible electron cholesteric phases in the cuprates.  The role of spin-orbit-coupling in superconductivity in two dimensions. By FY16, our work in earlier years on conductivity in two-dimensional systems with engineerable spin-orbit effects, including complex oxide heterostructres and topological insulator/superconductor hybrid systems, will have laid the ground for a systematic study of the dependence of the superconducting state on spin-orbit coupling.

Collaborations A. Andreev (U. of Washington); E. Bauer (LANL); L. Balicas (NHMFL); K. Behnia (ESPCI, Paris); Christopher Bell (University of Bristol, England); E. Berg (Weizmann); G. S. Boebinger (NHMFL); V. Brouet (Universite Paris Sud, France); S. Brown (UCLA); Christoph Brüne (Wuerzburg); S.L. Budko (Ames Laboaratory); Hartmut Buhmann (Wuerzburg); A. Carrington (Bristol, UK); A. Caldea (Oxford, UK); P. Canfield (Ames); R. Cava (Princeton University); S. Chandan (Purdue); A. V. Chubukov (U. of Wisconsin); S-B. Chung (UCLA); J. R. Cooper (Cambridge, UK); Y. Cui (Stanford University); N. Curro (UC Davis); L. DeGiorgi (ETH Zurich, Switzerland); T. P. Devereaux (Stanford); Rui Rui Du (Rice); S. Dugdale (Bristol, UK); H. Durr (Stanford University); C. B. Eom (Wisconsin); A. Finkelstein (Texas A&M); E. M. Forgan (Birmingham, UK); E. Fradkin (UIUC); M. Gabay(LPS, Orsay, France); D. Goldhaber-Gordon (Stanford); S. A. Grigera (St. Andrews); R. Hackl (WMI, Germany); W. P. Halperin (Northwestern); R-H. He (BC); J-P. Hu (Purdue); J. Hulliger (University of Berne, Switzerland); Z. Hussain (LBL); N. Hussey (Bristol, UK); Harold Y. Hwang (Stanford University); Z. Islam (APS, ANL); M. Jaime (NHMFL); B. Kalisky (Bar-Ilan University, Israel); A. Kaminsky (Ames Lab); E-A. Kim (Cornell); Y-J Kim (Toronto), R. Knight (Stanford); M. Kramer (Ames Lab); T. Lemberger (Ohio State University); D-H. Lee (UCB); A. P. M. Mackenzie (St Andrews, UK); Jochen Mannhart (Max-Planck Stuttgart, Germany); M. B. Maple (UCSD); C. Marcus (University of Copenhagen, Denmark); Nadya Mason (Urbana); R. McDonald (NHMFL); J. Mesot (PSI); D. Mihailovic (Lubljana, Slovenia); F. Milleto-Fabrizio (University of Naples, Italy); L Molenkamp (Wuerzburg); J. Moodera (MIT); R. G. Moore (Stanford); J. Orenstein (LBNL); A. Palevski (Tel Aviv University, Israel); S. Parameswaran (UCB); R. Prozorov (Ames); A. Reid (Stanford University); A. W. Rost (St. Andrews); M. Rudner (Harvard); R. Shankar (Yale); Z-X. Shen (Stanford); K. Shih (University of Texas, Austin); B.Z. Spivak (U of Washington); S. Stemmer (U.C.S.B.); M. Stone (Oak Ridge); M. Tanatar (Ames Laboratory); M. F. Toney (SSRL); S. Tozer (NHMFL); J. Tranquada (BNL); K. Wang (UCLA); S.R. White (UCI); M. Wolf (Berlin, Germany); M. Wuttig (RWTH, Aachen, Germany); Q. Xue (Tsinghua University, China); Hong Yao (Tsinghua).

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Correlated Materials - Synthesis and Physical Properties FWP#: 10028

Publications for FY13 & FY14 (Oct 1st 2012 to date) (Oct 1st 2012 – Dec 31st 2012) 1) Magneto-elastically coupled structural, magnetic and superconducting order parameters in BaFe2(As1-xPx)2, H-.H. Kuo, J. G. Analytis, J.-H. Chu, R.M. Fernandes, J. Schmalian and I. R. Fisher, Phys. Rev. B 86, 134507 (2012) [7 pages] – Published 4 October 2012

2) Alternative route to charge density wave formation in multiband systems, Hans-Martin Eiter, Michela Lavagnini, Rudi Hackl, Elizabeth A. Nowadnick, Alexander F. Kemper, Thomas P. Devereaux, Jiun-Haw Chu, James G. Analytis, Ian R. Fisher, and Leonardo Degiorgi, PNAS early edition doi/10.1073/pnas.1214745110 Published online Decemeber 2012

3) High-Temperature Superconductivity – Ineluctable Complexity, E. Fradkin and S. A. Kivelson, Nature Phys. 8, 864-66 (2012). [Published Dec. 2012]

4) Microscopic Model of Quasiparticle Wave Packets in Superfluids, Superconductors, and Paired Hall States, S. A. Parameswaran, S. A. Kivelson, R. Shankar, S. L. Sondhi, and B. Z. Spivak, Phys. Rev. Lett. 109, 237004 (2012). [Published Dec. 5, 2012]

5) Charge and spin collective modes in a quasi-one-dimensional model of Sr2RuO4, Suk Bum Chung, Srinivas Raghu, Aharon Kapitulnik, Steven A. Kivelson, Phys. Rev. B 86, 064525 (2012).

6) Magneto-optical measurements of a cascade of transitions in superconducting La1.875Ba0.125CuO4 single crystals, Hovnatan Karapetyan, M. Hucker, G. D. Gu, J. M. Tranquada, M. M. Fejer, Jing Xia, A. Kapitulnik, Phys. Rev. Lett. 109, 147001 (2012).

7) Agreement between local and global measurements of the London penetration depth, Thomas M. Lippman, Beena Kalisky, Hyunsoo Kim, Makariy A. Tanatar, Sergey L. Bud'ko, Paul C. Canfield, Ruslan Prozorov, Kathryn A. Moler Physica C Volume 483 (2012), Pages 91–93 93 (Published 14 December 2012).

(2013) 8) Giant atomic displacement at a magnetic phase transition in metastable Mn3O4, S. Hirai, A. M. dos Santos, M. C. Shapiro, J. J. Molaison, N. Pradhan, M. Guthrie, C. A. Tulk, I. R. Fisher, and W. L. Mao, Phys. Rev. B 87, 014417 (2013) [6 pages] – Published 14 January 2013

9) Observation of Temperature-Induced Crossover to an Orbital-Selective Mott Phase in AxFe2-ySe2 (A=K, Rb) Superconductors, M. Yi, D. H. Lu, R. Yu, S. C. Riggs, J.-H. Chu, B. Lv, Z. K. Liu, M. Lu, Y.-T. Cui, M. Hashimoto, S.-K. Mo, Z. Hussain, C. W. Chu, I. R. Fisher, Q. Si, and Z.-X. Shen, Phys. Rev. Lett. 110, 067003 (2013) [5 pages] – Published 5 February 2013

10) Dynamics of Photoexcited Carriers in Ba(Fe1-xCo x)2As2 Single Crystals with Spin-Density-Wave Ordering, L. Stojchevska, T. Mertelj, Juin-Haw Chu, Ian R. Fisher, D. Mihailovic, J. Supercond. Nov. Magn. DOI 10.1007/s10948-013-2141-4 (2013) [4 pages] – Published online18th March 2013

11) Incoherent Topological Defect Recombination Dynamics in TbTe3, T. Mertelj, P. Kusar, V.V. Kabanov, P. Giraldo-Gallo, I. R. Fisher, and D. Mihailovic, Phys. Rev. Lett. 110, 156401 (2013) [4 pages] – Published 9 April 2013

12) Charge transfer and multiple density waves in the rare earth tellurides, A. Banerjee, Yejun Feng, D. M. Silevitch, Jiyang Wang, J. C. Lang, H.-H. Kuo, I. R. Fisher, and T. F. Rosenbaum, Phys. Rev. B 87, 155131 (2013) [6 pages] – Published 16 April 2013

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Correlated Materials - Synthesis and Physical Properties FWP#: 10028

13) Kerr effect as evidence of gyrotropic order in the cuprates, Pavan Hosur, A. Kapitulnik, S.A. Kivelson, J. Orenstein, S. Raghu, Phys. Rev. B 87, 115116 (2013).

14) Imaging currents in HgTe quantum wells in the quantum spin Hall regime, Katja C. Nowack, Eric M. Spanton, Matthias Baenninger, Markus König, John R. Kirtley, Beena Kalisky, C. Ames, Philipp Leubner, Christoph Brüne, Hartmut Buhmann, Laurens W. Molenkamp, David Goldhaber-Gordon, Kathryn A. Moler Nature Materials 12, pp 787–791 (Published 01 September 2013).

15) Locally enhanced conductivity due to tetragonal domain structure in LaAlO3/SrTiO3 heterointerfaces, Beena Kalisky , Eric Spanton, Hilary Noad , John Kirtley, Katja Nowack , Christopher Bell , Hiroki Sato , Masayuki Hosoda , Yanwu Xie , Yasuyuki Hikita , Carsten Woltmann , Georg Pfanzelt , Rainer Jany , Christoph Richter , Harold Hwang , Jochen Mannhart, Kathryn Moler Nature Materials 12, pp 1091-1095 (Published 01 December 2013).

16) Infrared study of the electronic structure of the metallic pyrochlore iridate Bi2Ir2O7, Y. S. Lee, S. J. Moon, Scott C. Riggs, M. C. Shapiro, I. R. Fisher, Bradford W. Fulfer, Julia Y. Chan, A. F. Kemper, and D. N. Basov, Phys. Rev. B 87, 195143 (2013) [7 pages] – Published 30 May 2013

17) Direct Measurement of Current-Phase Relations in Superconductor/Topological Insulator/Superconductor Junctions, Ilya Sochnikov, Andrew J. Bestwick, James R. Williams, Thomas M. Lippman, Ian R. Fisher, David Goldhaber- Gordon, John R. Kirtley, and Kathryn A. Moler, Nano Letters, 13 (7), pp 3086–3092 (June 2013).

18) Measurement of the elastoresistivity coefficients of the underdoped iron arsenide Ba(Fe0.975Co0.025)2As2, Hsueh-Hui Kuo, Maxwell C. Shapiro, Scott C. Riggs, and Ian R. Fisher, Phys. Rev. B 88, 085113 (2013) [9 pages] – Published 12 August 2013

19) Imaging currents in HgTe quantum wells in the quantum spin Hall regime Katja C. Nowack, Eric M. Spanton, Matthias Baenninger, Markus König, John R. Kirtley, Beena Kalisky, C. Ames, Philipp Leubner, Christoph Brüne, Hartmut Buhmann, Laurens W. Molenkamp, David Goldhaber-Gordon, Kathryn A. Moler, Nature Materials 12, pp 787–791 (Published 01 September 2013).

20) Direct Optical Coupling to an Unoccupied Dirac Surface State in the Topological Insulator Bi2Se3 J. A. Sobota, S.-L. Yang, A. F. Kemper, J. J. Lee, F. T. Schmitt, W. Li, R. G. Moore, J. G. Analytis, I. R. Fisher, P. S. Kirchmann, T. P. Devereaux, and Z.-X. Shen Phys. Rev. Lett. 111, 136802 (2013) – Published 23 September 2013

21) Emerging Weak Localization Effects on Topological Insulator-Insulating Ferromagnet (Bi2Se3-EuS) Interface Qi I. Yang, Merav Dolev, Li Zhang, Jinfeng Zhao, Alexander D. Fried, Elizabeth Schemm, Min Liu, Alexander Palevski, Ann F. Marshall, Subhash H. Risbud, Aharon Kapitulnik, Phys. Rev. B 88, 081407(R) (2013)

22) Field theory of a quantum Hall nematic transition, J. Maciejko, B. Hsu, S. A. Kivelson, Y. Park, and S. L. Sondhi, Phys. Rev. B 88, 125137 (2013).

23) Band structure effects on superconductivity in Hubbard models, W-J. Cho, R. Thomale, S. Raghu, and S. A. Kivelson, Phys. Rev. B 88, 64505 (2013).

24) Correlations and renormalization of the electron-phonon coupling in the honeycomb Hubbard ladder and superconductivity in polyacene, G. Karakonstantakis, L. Liu, R. Thomale, and S. A. Kivelson, Phys. Rev. B 88, 224512 (2013).

25) Evidence from tunneling spectroscopy for a quasi-one dimensional origin of superconductivity in Sr2RuO4, I. A. Firmo, S. Lederer, C. Lupien, A. P. Mackenzie, J. C. Davis and S. A. Kivelson, Phys. Rev. B 88, 134521 (2013).

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Correlated Materials - Synthesis and Physical Properties FWP#: 10028

(2014 to date) 26) Transport near a quantum critical point in BaFe2(As1-xPx)2, James G. Analytis, H-H. Kuo, Ross D. McDonald, MarkWartenbe, P. M. C. Rourke, N. E. Hussey and I. R. Fisher, Nature Physics 10, 194–197 (2014) [4 pages] – Published online 19 January 2014

27) Hysteretic behavior in the optical response of the underdoped Fe-arsenide Ba(Fe1-xCox)2As2 in the electronic nematic phase C. Mirri, A. Dusza, S. Bastelberger, J.-H. Chu, H.-H. Kuo, I. R. Fisher, and L. Degiorgi, Phys. Rev. B 89, 060501(R) (2014) [5 pages] – Published 7 February 2014

28) Spectrally resolved femtosecond reflectivity relaxation dynamics in undoped spin-density wave 122-structure iron-based pnictides A. Pogrebna, N.Vujicic, T. Mertelj, T. Borzda, G. Cao, Z. A. Xu, J.-H. Chu, I. R. Fisher, and D. Mihailovic, Phys. Rev. B 89, 165131 (2014) [9 pages] – Published 24 April 2014

29) Dynamic competition between spin-density wave order and superconductivity in underdoped Ba1-xKxFe2As2 M. Yi, Y. Zhang, Z.-K. Liu, X. Ding, J.-H. Chu, A.F. Kemper, N. Plonka, B. Moritz, M. Hashimoto, S.-K. Mo, Z. Hussain, T.P. Devereaux, I.R. Fisher, H.H. Wen, Z.-X. Shen & D.H. Lu, Nature Communications DOI: 10.1038/ncomms4711 [7 pages] – Published 25 April 2014

30) Evidence of Chiral Order in the Charge-Ordered Phase of Superconducting La1.875Ba0.125CuO4 Single Crystals Using Polar Kerr-Effect Measurements, Hovnatan Karapetyan, Jing Xia, M. Hucker, G. D. Gu, J. M. Tranquada, M.M. Fejer, A. Kapitulnik, Phys. Rev. Lett 112, 047003 (2014)

31) Pulsed Laser Deposition of High-Quality Thin Films of the Insulating Ferromagnet EuS Qi I. Yang, Jinfeng Zhao, Li Zhang, Merav Dolev, Alexander D. Fried, Ann F. Marshall, Subhash H. Risbud, Aharon Kapitulnik, Appl. Phys. Lett. 104, 082402 (2014)

32) Observation of Broken Time-Reversal Symmetry in the B Phase of the Heavy Fermion Superconductor UPt3 E. R. Schemm, W. J. Gannon, C. Wishne, W. P. Halperin, A. Kapitulnik, Accepted for publication in Science (2014)

33) Quenched disorder and vestigial nematicity in the pseudo-gap regime of the cuprates, L Nie, G. Tarjus, and S. A. Kivelson, PNAS in press.

34) Images of edge current in InAs/GaSb quantum wells Eric M. Spanton, Katja C. Nowack, Lingjie Du, Gerald Sullivan, Rui-Rui Du, Kathryn A. Moler arXiv:1401.1531

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Spin Physics FWP#: 10029

Spin Physics Principal Investigator(s): David Goldhaber-Gordon, Hari Manoharan, Joeseph Orenstein, Shoucheng Zhang Postdoctoral Scholars and Graduate Students: Reyes Calvo, Eric Chatterjee, Alex Contryman, John Hughs, F. C. Niestemski, Shreyas Patankar, Matt Pelliccione, Dominik Rastawicki, Jing Wang, and Gang Xu

Overview The Spin Physics program investigates novel phenomena arising from spin-orbit coupling in solids. In conventional semiconductors, spin-orbit coupling gives the possibility of electric manipulation of the spin degrees of freedom, which can be used for data storage and information processing. More recently, it is realized that spin-orbit coupling can lead to a fundamentally new state of matter, the topological insulator. These materials have an energy gap in the bulk, and a conducting topological state on the surface. The spin program develops theoretical concepts and experimental tools to investigate these novel effects.

Progress in FY2014 Zhang group has theoretically predicted the quantum anomalous Hall (QAH) effect in magnetic topological insulators. Recently, this theoretical prediction has been confirmed experimentally in Cr doped topological insulator (Sb,Bi)2Te3. Zhang group published five papers on QAH effect. In the first paper, we present a general theory for QAH effect with higher Chern numbers, and show by first-principles calculations that thin film magnetic TI of Cr-doped Bi2(Se,Te)3 is a candidate for the c=2 QAH insulator. In the second paper, we predict by first-principles calculations that thin films of a Cr-doped (Bi,Sb)2Te3 magnetic topological insulator have gapless nonchiral edge states coexisting with the chiral edge state, which would explain dissipative transport in the quantum anomalous Hall (QAH) state experimentally observed in this system. In the third paper, we propose that in the ferromagnetic EuO/CdO quantum well, the QAH effect can be realized with high Curie temperature and larger band gap. In the fourth paper, we study the critical properties of the quantum anomalous Hall (QAH) plateau transition in magnetic topological insulators. We predict that an intermediate plateau with zero Hall conductance could occur at the coercive field. σxx would have double peaks at the coercivity while ρxx only has single peak. In the fifth paper, we propose the QAH effect could be realized in heavily doped junction quantum wells due to inverted band structure induced by internal electric field, such as InSb and HgTe.

Zhang group has theoretically predicted the quantum spin Hall (QSH) effect in HgTe quantum well as well as topological insulators Bi2Se3. In a recent paper, we predict by the first principles calculations, that QSH insulators could be realized in two-dimensional tin film called stanene. This materials have band gap as large as 0.3 eV, sufficiently large for practical applications at room temperature. This remarkable result generated much interest in the community, and is broadly covered in scientific press, including the NY Times.

Zhang group has theoretically proposed the concept of time-reversal invariant topological superconductivity. Recently, we propose that topological superconductivity in a doped quantum spin Hall insulator. A wealth of QSH insulating materials could lead to the discovery of the TRI topological superconductor. Specifically, we propose that two- dimensional doped tin film as a potential candidate.

Orenstein, Goldhaber-Gordon, Manoharan and Zhang are actively working together on the ferromagnetism of Cr doped topological insulator (Sb,Bi)2Te3. We performed measurements of magneto-optic Kerr effect in this material, which provides an alternative and accurate quantification of magnetization. Kerr rotation was measured as a function of applied magnetic field and of temperature, as well as gate voltage. We have also achieved nearly-quantized anomalous Hall effect in transport, as we prepare to build on last year’s discovery of quantized anomalous Hall effect in Tsinghua and determine what are the sources of parallel conduction (and thus deviation from perfect quantization).

Manoharan and Zhang are actively working together on the half-metallic surface state of NaCoO2 as a platform for topological superconductivity and Majorana fermions though the mechanism of s-wave superconductivity proximity effect. Manoharan performed STM measurements on the surface states of NaCoO2, and distinguished the p-type doping surface region. The observed local density of states (LDOS) by STM experiments quantitatively agree with Zhang group's ab initio calculations, indicating the single Fermi surface on NaCoO2. The single surface state was confirmed by ARPES experiments done by Yulin Chen. The magnetization of the surface states was confirmed by measurements of the magneto-optical Kerr effect by Orenstein group revealing a remnant magnetization of the state with a critical temperature T ~ 15 K, in agreement with T-dependent scanning tunneling spectroscopy performed by Manoharan group.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Spin Physics FWP#: 10029

Expected Progress in FY2015 Manoharan and Zhang plan to investigate the vortex state of the proximity coupled system of superconductor with NaCoO2, and measure the tunneling spectrum of the core states, to observe possible signatures of the Majorana bound state at zero energy. Together with Manoharan and Harold Hwang of MSD/SLAC, Orenstein will perform optical measurements on systems with strong spin-orbit coupling, such as BiTeI and the interface of superconductors grown on small gap semiconductors. Goldhaber-Gordon will perform transport measurements on these systems, particularly the semiconducting ones. Orenstein and Zhang plan to investigate the magnetic order in Cr-doped topological insulators, and study the mechanism for ferromagnetism in the insulating regime. Together with Manoharan and Goldhaber-Gordon, Orenstein will perform systematic magneto-optic Kerr measurements on this system. Zhang plans to perform detailed theoretical calculations on the ferromagnetic order and Kerr rotation angle at different chemical potential and compare with the experimental data.

Expected Progress in FY2016 Manoharan and Zhang plan to investigate the proximity coupling between superconductors and the quantum anomalous Hall state, and confirm the coupling by measuring the tunneling spectrum. Moreover, Manoharan and Zhang plan to investigate the vortex state of this proximity coupled superconductor, and measure the tunneling spectrum of the core states, to observe possible signatures of the Majorana bound state at zero energy. Goldhaber-Gordon will perform transport measurements on these systems, in order to confirm the chiral topological superconductivity in this system.

Collaborations L. Molenkamp (Wuerzburg Germany), Zhong Fang, Xi Dai, Yayu Wang and Qikun Xue (Beijing China), Chao-Xing Liu (Penn State), Rui-Rui Du (Rice), Yulin Chen (Cambridge)

Publications for FY13 & FY14 (Oct 1st 2012 to date) Peer-Reviewed Journal Articles 1. Jing Wang, Biao Lian, Haijun Zhang, Yong Xu and Shou-Cheng Zhang, “Quantum Anomalous Hall Effect with Higher Plateaus,” Physical Review Letters 111, 136801 (2013). 2. Jing Wang, Biao Lian, Haijun Zhang, and Shou-Cheng Zhang, “Anomalous Edge Transport in the Quantum Anomalous Hall State,” Physical Review Letters 111, 086803 (2013). 3. Yong Xu, Binghai Yan, Haijun Zhang, Jing Wang, Gang Xu, Peize Tang, Wenhui Duan, Shou-Cheng Zhang, “Large-gap Quantum Spin Hall Insulators in Tin Films,” Physical Review Letters 111, 136804 (2013). 4. Haijun Zhang, Chao-Xing Liu, and Shou-Cheng Zhang, “Spin-Orbital Texture in Topological Insulators,” Physical Review Letters 111, 066801 (2013). 5. Jing Wang, Hideo Mabuchi, and Xiao-Liang Qi, “Calculation of divergent photon absorption in ultrathin films of a topological insulator,” Physical Review B 88, 195127 (2013). 6. Katja C. Nowack, Eric M. Spanton, Matthias Baenninger, Markus König, John R. Kirtley, Beena Kalisky, C. Ames, Philipp Leubner, Christoph Brüne, Hartmut Buhmann, Laurens W. Molenkamp, David Goldhaber-Gordon and Kathryn A. Moler, “Imaging currents in HgTe quantum wells in the quantum spin Hall regime,” Nature Materials 12, 787 (2013). 7. Marco Polini, Francisco Guinea, Maciej Lewenstein, Hari C. Manoharan, and Vittorio Pellegrini, “Artificial graphene as a tunable Dirac material,” Nature Nanotechnology 8, 625 (2013). 8. Markus König, Matthias Baenninger, Andrei G. F. Garcia, Nahid Harjee, Beth L. Pruitt, C. Ames, Philipp Leubner, Christoph Brüne, Hartmut Buhmann, Laurens W. Molenkamp, David Goldhaber-Gordon,"Spatially Resolved Study of Backscattering in the Quantum Spin Hall State" Physical Review X 3, 021003 (2013). 9. Jing Wang, Biao Lian, and Shou-Cheng Zhang, “Universal scaling of the quantum anomalous Hall plateau transition,” Physical Review B 89, 085106 (2014). 10. Haijun Zhang, Jing Wang, Gang Xu, Yong Xu, and Shou-Cheng Zhang, “Topological States in Ferromagnetic EuO/CdO Superlattices and Quantum Wells,” Physical Review Letters 112, 096804 (2014).

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Spin Physics FWP#: 10029

11. Jason C. Randel, Francis C. Niestemski, Andrés R. Botello-Mendez, Warren Mar, Georges Ndabashimiye, Sorin Melinte, Jeremy E. P. Dahl, Robert M. K. Carlson, Ekaterina D. Butova, Andrey A. Fokin, Peter R. Schreiner, Jean- Christophe Charlier, and Hari C. Manoharan, “Unconventional Molecule-Resolved Current Rectification in Diamondoid-Fullerene Hybrids,” Nature Communications, in press (2014). 12. Haijun Zhang, Yong Xu, Jing Wang, and Shou-Cheng Zhang, “Quantum Spin Hall and Quantum Anomalous Hall States Realized in Junction Quantum Wells,” arXiv: 1402.5167 (accepted by Physical Review Letters) 13. Jing Wang, Biao Lian, and Shou-Cheng Zhang, “Two-Dimensional Time-Reversal-Invariant Topological Superconductivity in Tin Films,” submitted to Physical Review Letters (arXiv: 1402.4433, 2014/02/18). 14. Carolina Parra, Francis C. Niestemski, Alex W. Contryman, Paula Giraldo-Gallo, Theodore H. Geballe, Ian R. Fisher and Hari C. Manoharan, “Emergent electronic granularity within a three-dimensional material in the proximity of a superconductor-insulator transition,” submitted to Nature Physics (2014).

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted:: 6/23/2014 SIMES: Clathrin Biotemplating FWP#: 10031

Clathrin Biotemplating Principal Investigators: Sarah Heilshorn, Sebastian Doniach, Nickolas MeMelosh, Andrew Spakowitz Postdoctoral Scholars and Graduate Students: Nick Cordella, Kelly Huggins, Yifan Kong, Christopher Madl, Shifan Mao, and Derek Mendez

Overview The focus of this multi-disciplinary research program is to characterize and exploit the tailored molecular interactions inherent in biological systems. Such understanding will enable deterministic formation of complex organic/inorganic constructs and engineering of responsive, biomimetic materials that exhibit self- healing and self-regulating transformations. These materials will lead to fundamentally new designs in biomimetic organic/inorganic devices for energy storage, catalysis, solar cells, and fuel cells. The team integrates a wide range of experimental and theoretical approaches to assemble, characterize, and model dynamic assembly. Our recent collaborative effort has focused on experimmental and theoretical insights into the fundamentals of biomimetic self-assembly in two and three dimensions, investigating the effects of multivalency on hierarchical assembly processes, extending our strategy for non-covalent, site-specific functionalization of clathrin protein assemblies to template multiple inorganic species simultaneously on the same protein particle, and developing advanced x-ray characterization techniques for atomic scale resolution of biomaterials with local order but disorder at large length scales.

Progrress in FY2014 A breakthrough in X-ray science: Correlated X-ray Scattering of soft materials (Doniach, Spakowitz) Tools to study disordered systems with local structural order, such as proteins in solution, remain limited. Such understanding is essential for determining molecular structure of biopolymer materials that are locally ordered but disordered at large length scales. Use of Correlated X-ray Scattering (CXS) to study molecular structure was proposeed theoretically by Kam in 1977 [Macromolecules 10, 927–934]. The advent of improved X-ray sources and detectors since that time has led to the experimental feasibility of this structural technique. Correlated X-ray scattering (CXS) has recently attracted new interest as a way to leverage next-generation light sources to study such disordered matter. The CXS experiment measures angular correlations of the intensity caused by the scattering of X-rays from an ensemble of identical, internally structured particles with disordered orientation and position. The Doniach lab has recently achieved a breakthrough in X-ray science by demonstrating for the first time the Figure 1. (a) From top to bottom, measured correlation functions D(q111, q200, D), D(q111, q111, feasibility of CXS to obtain structural information at atomic D) and D(q200, q200, D) from 20 nm silver NPs. resolution for disordered systems of ordered objects, Fig. 1 The angular range is truncated to highlight the [6]. In our publication, we report on experimental work in correlation peaks. Regions not shown contain similar which CXS signals were obtained for an ensemble of 20 nm artifacts, with nothing greater in magnitude than the CXS peaks. (b) Corresponding simulations of the silver nanoparticles in three dimensions. We averaged over correlations plotted in (a). Vertical lines mark 15,496 snapshot X-ray images obtained by exposing a series of analytical predictions. (c) Simulation (dashed line) and samples of silver nanoparticles in solution to a micro-focuseed measurement (diamond marker) of a correlation peak synchrotron radiation beam. Of order 109 particles were width. Peak width scales inversely with particle size, exposed to the X-ray beam in each shot. Angular correlationns hence we expect the measured CXS resulted from particles larger than 20 nm. Shading represents 95% were measured at wide angles corresponding to atomic confidence intervals. resolution and were shown to match theoretical predictions.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Clathrin Biotemplating FWP#: 10031

Theoretical modeling of clathrin structure and responsive tranformations (Spakowitz, Melosh, Heilshorn) We developed a theoretical model of a clathrin protein lattice on a flexible membrane. The clathrin subunit is modeled as a three-legged pinwheel with elastic deformation modes and inter-subunit binding interactions, Fig. 2. The pinwheels are constrained to lie on the surface of an elastic sheet that opposes bending deformation and is subjected to tension. Through Monte Carlo simulations, we predict the equilibrium phase behavior of clathrin lattices at various levels of tension, predicting the conditions where the lattice exhibits solid and fluid phases [1]. These results provide an approach for collective changes in assembly behavior from subtle environmental cues. We then address the impact of local nanoscale indentations in modulating the local phase behavior of the clathrin lattices. Our work provides a basis for utilizing local deformations in triggering 3-dimensional vesicle budding from reorganization of 2-dimensional clathrin lattices. Ongoing work involves direct comparison of the theoretical predictions with experimental measurements.

Figure 2. Left, our model of clathrin on a fluctuating membrane that is subjected to a nanoscale indentation. Right, Monte Carlo simulations of our model reveal a physical mechanism where local curvature induces a phase transition to a fluid phase, resulting in a responsive lattice that is able to form local 3D budding indentations on the membrane.

A biomimetic system for 2-dimensional assembly of multi-functional subunits (Melosh, Heilshorn) In order to extend the lessons learned about the self-assembly of clathrin, we’ve begun to design new systems that can be produced in larger quantities and tailored to our specific needs. To this end we are employing lithography based nanofabrication techniques to create self-assembling particles across the 100 nm – 10 μm scale with several of the characteristics of clathrin (3-legged structure, localized binding sites, propensity to attach to 2D interfaces) in order to analyze their self-assembly dyynnamics. By selective functionalization of the particle faces, we can order them onto fluid 2D air-water inteerfaces and manipulate their self-assembly structurally and chemically. These particles have been fabricated as micron-sized structural analogues of clathrin to enable direct visualization of their self-assembling behavior by optical microscopy. While these micron-sized particles are interesting self-assembling systems, their energetics are different than clathrin due to their size and high surface tension on the 2D interface. Using e-beam lithography we have developed a strategy to build 100 nm particles, similar in size and functionality to clathrin. To avoid the domination of surface tension effects, we devised a scheme to embed the particles within a lipid bilayer, thus confining them to a 2D system with very little lateral surface tension. The architecture is a particle three layers thick with a gold bandd in the middle that can be functionalized hydrophobically. If the bands are on the same scale as the inner hydrophobic portion of the self-assembled lipid membrane, then the particles are able to interface stably. Changing the geometry of the particles and the surface functionalization enables direct exploration of 2D self-assembly, allowing fine-tuning of the interaction strength between particles and an ideal system for studying self-asseembly dynamics.

Clathrin templates to direct nanoparticle clustering and bimetallic composites (Heilshorn, Melosh) We previously reported the functionalization of self-assembled clathrin protein cages to enable synthesis of nanoparticles from a range of inorganic materials. Recently, we investigated the ability of this engineered biomolecular complex to act as a tunable nanoreactor for the formation of different arrangements of gold nanoparticles in 3D [2]. We found that self-assembled clathrin cages functionalized with engineered bi- functional peptides induced formation of gold nanoparticles to generate solutions of either dispersed or clustered gold nanoparticles on demand. The 3D arrangement of nanoparticles is dependent on the

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted:: 6/23/2014 SIMES: Clathrin Biotemplating FWP#: 10031 concentration of the engineered peptide, which fulfills multiple roles in the synthesis process including stabilization of the nanoparticle surface and localization of the nanoparticles within the self-assembled clathrin cage. We proposed and experimentally verified a mechanism that allows us to predict the peptide concentration at which the nanoreactor behavior switches, Fig. 3. This work provides insight into peptide-based surfactants and the potential for incorporating them into strategies for tuning biological templating processes in mild solution conditionns to generate complex structures.

Expected Progress in FY2015 Results taken on beam line 12-2 at SSRL (Doniach) indicate that CXS experiments on disordered ensembles of locally orrdered soft matter, such as proteins or DNA in solution, will be feasible in the future. In order to be able to see CXS on soft materialss, the intense X-ray pulses from XFEL are necessary. CXS involves measuring the contributions to the total scattering in which pairs of scattering events come from the same particle. To have a statistically significant fraction of the observed scattering contributed by such correlated pairs of events requires a high X- ray fluence, which would not be sustainable by a protein or DNA Figure 3. a) Schematic of potential paarticle growth molecule at a continuous X-ray source such as the one we used for mechanism in the case of high TP-Au peptide the metallic nanoparticles. The big advantage of XFEL sources is concentration (top) or low peptide concentration that they allow for “diffract then destroy” measurements in which (bottom). (b, c) TEM micrographs of gold nanoparticle synthesis reactions containing clathrin a single XFEL pulse gives sufficient signal that the probabillity of cages and 67.6 M (b) or 33.8 M (c) TP-Au doubly scattering events constitutes a useable fraction of the total peptide. (d, e) Radial distribution function analysis scattering before the radiation destroys the particle [Spence JCH, of TEM data, indicating the degree of clustering Weierstall U, Chapman HN. Rep. Prog. Phys. 2012, 75:102601]. present in panels (b) and (c), respectively. In the current fiscal year we were able to take measurements both at the LCLS and the Japanese XFEL, SACLA. Analysis of this data is still ongoing. We plan to extend our previous studies of metallic nanoparticles to examine the atomic structure of iron oxide nanoparticles and ferritin protein nanoparticles at atomic resolution. Furthermore, short segments of double-stranded DNA possess considerable rigidity and in many ways acts as a nanocrystal. We plan to apply CXS to study such DNA samples with exploratory beamtime at the LCLS. Future plans in the Spakowitz lab aim to address how topological changes in DNA can trigger large- scale conformational changes in single DNA strands and in DNA materials. Building on our recent work in modeling chromosomal DNA in Caulobacter [6], we have eestablished a multi-scale model for supercoiled DNA that is able to capture physical behavior from basepairs to genomic lengths. We will leverage this model to capture the response of circular and network DNA to topological changes, establishing a novel material platform that utilizes polymer topology as a mechanism for structural rearrangements. Experimental design, synthesis, and characterization of these self-assembling, dynamic DNA-baased materials will be performed by the Heilshorn lab using a combination of synthetic polymer and enzyme biiochemistry approaches. Goals in the Melosh lab for the next year are to insert the nanofabricated, biomimetic particles into lipid liposomes and planar bilayers and to observe the changes in their self-assembly as a function of geometry and functionalization. By changing the shape and functionaliization of the particles we aim to mechanically control the underlying lipid support in a similar way to clathrin. We also aim to use the surface properties of these particles to localize secondary, non-membrane-interacting structures to the particles. These hierarchical self-assembled structures would enable additional functionality to be designed into the clathrin mimetic system in a manner similar to the TEThER peptide strategy developed by Heilshorn.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Clathrin Biotemplating FWP#: 10031

Expected Progress in FY2016 Inspired by work on chromosomal DNA packaging, the Spakowitz lab will develop a field theoretic model of random copolymers to predict the microphase segregation in these structured materials. Using both Monte Carlo simulation and analytical field theory, we will develop the phase diagram for random copolymers and predict the structure factor for the microphase segregation. These results will be used to understand both DNA organization as well as the microstructure of polymer membranes for fuel cell applications. In collaboration with Lucy Shapiro and Harley McAdams, Spakowitz and Doniach recently published results from Brownian dynamics simulations of the packing of supercoiled DNA polymers in the elongated cell-like confinement of the bacterial environment and were able to show that this packing is consistent with a branched DNA structure [5]. We plan to extend the application of CXS to examine DNA samples in assembled bacterial chromosomes. Understanding the physical basis for the observed DNA packing is critical for interpreting the role of structural complexity in a multitude of chromosomal processes including gene regulation, recombination, and chromosome segregation and serves as a basis for understanding DNA organization in structured materials. These CXS structural measurements of supercoiled DNA will be interpreted using theoretical models developed by the Spakowitz lab described above. Heilshorn and Melosh will utilize these insights to design DNA-based nanomaterials that exploit supercoiling transitions to achieve a range of dynamic behaviors.

Collaborations 1. Gordon E. Brown, Stanford, Geology; 2. Mirjam Leunissen, Foundation for Fundamental Research on Matter (FOM) Institute AMOLF, Amsterdam, The Netherlands; 3. Harley McAdams, Stanford, Biochemistry; 4. Vijay Pande, Stanford, Chemistry; 5. Daniel Ratner, staff scientist, LCLS/SLAC; 6. Lucy Shapiro, Stanford, Biochemistry; 7. Jim Spudich, Stanford, Biochemistry.

Publications for FY13 & FY14 (Oct 1st 2012 to date) Peer-Reviewed Journal Articles - Full DOE Support 1. Cordella N, Lampo TJ, Mehraeen S, Spakowitz AJ. Membrane fluctuations destabilize clathrin protein lattice order. Biophysical Journal, 2014, 106(7):1476-1488. 2. Schoen AP, Huggins KNL, Heilshorn SC. Engineered clathrin nanoreactors provide tunable control over gold nanoparticle synthesis and clustering. Journal of Materials Chemistry B, 2013, 1:6662-6669. 3. Schoen AP, Cordella N, Mehraeen S, Arunagirinathan MA, Spakowitz AJ, Heilshorn SC. Dynamic remodeling of disordered protein aggregates is an alternative pathway to achieve robust self-assembly of nanostructures. Soft Matter, 2013, 9(38): 9137-9145. 4. Schoen AP, Hommersom B, Heilshorn SC, Leunissen ME. Tuning colloidal association with specific peptide interactions. Soft Matter, 2013, 9(29): 6781-6785.

Peer-Reviewed Journal Articles - Partial DOE Support 5. Hong SH, Toro E, Mortensen KI, Díaz de la Rosa MA, Doniach S, Shapiro L, Spakowitz AJ, McAdams HH. Caulobacter chromosome in vivo configuration matches model predictions for a supercoiled polymer in a cell-like confinement. Proceedings of the National Academy of Sciences USA, 2013, 110(5):1674- 1679. 6. Mendez D, Lane TJ, Sung J, Sellberg J, Levard C, Watkins H, Cohen AE, Soltis M, Sutton S, Spudich J, Pande V, Ratner D, Doniach S. Observation of correlated X-ray scattering at atomic resolution. Philosophical Transactions of the Royal Society B, 2014, 20130315, accepted and to appear in print June 9, 2014.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Magnetization & Dynamics FWP#: 10067

Magnetization & Dynamics Principal Investigator(s): Hermann Dürr, Matthias Hoffmann, Katheryn Moler, Joachim Stöhr Staff Scientists: John Kirtley, Alexander Reid Postdoctoral Scholars and Graduate Students: Stefano Bonetti, Tyler Chase, Zhao Chen, Patrick Granitzka, Catherine Graves Alexander Gray, Daniel Higley, Roopali Kukreja, TianMin Liu, Tianhan Wang, and Yihua Wang Visiting Scientist: Patrick Granitzka

Overview The FWP aims at developing a world leading program to understand and control the nanoscale dynamics of complex magnetic materials using soft x-rays at the Linac Coherent Light Source (LCLS) and the Stanford Synchrotron Radiation Laboratory (SSRL). These activities are complemented by laser and electron beam based studies using intense THz pulses to control spin and charge motion in materials. The program addresses the grand challenge problems of emergence of mesoscale spin & charge order far (or even very far) from equilibrium with the specific goal of impacting information technology, a key area underlying US competitiveness and scientific and technological advances in our modern data centric world. The research thrusts in the FWP focus at developing a microscopic understanding of (1) all- optical magnetic switching in metallic alloys, and (2) electric field driven metal-insulator transitions in strongly correlated materials. (3) It also aims at developing a new generation of non-linear x-ray techniques such as stimulated inelastic x-ray scattering to uniquely probe the electronic and spin interactions in emergent mesoscopic phases.

Progress in FY2014 Significant progress has been achieved in all three research thrusts through successful experiments at SSRL, LCLS and other FEL sources. In the following, we outline our progress:

 Using the LCLS SXR beamline, we have continued to investigate all-optical magnetic switching in FeCoGd alloys using elastic resonant magnetic scattering o We discovered that strong laser-induced spin currents far from equilibrium can transport angular momentum over ~10 nm distances causing magnetization reversal at a distance. We used circularly polarized laser pulses to control these phenomena and achive all-optical switching of the sample magnetization. The data analysis of this LCLS experiment (March 2014) is currently underway) o We have studied the spin transport in FeCoGd at LCLS on picosecond timescales and observed evidence for ultrafst magnon propagation (publication in preparation).

 Using SSRL beamline 13, we have investigated the magnetic domain sizes for the latest generation of magnetic hard disc drives with elastic resonant magnetic scattering. These investigations performed in close collaboration with Hitach (HGST) provide valuable input for tailoring future device generations [2].

 We used VUV radiation form the Flash free electron laser to study the ultrafast demagnetization of Fe films following fs laser excitation. The results represent the first direct measurement of the sample magnetization in the tie domain as the photoemitted electron spin polarization was detected [3.4].

 We have investigated the magnetic domain sizes written by fs laser illumination of FeCoTb alloys. Such materials display all-optical magnetization reversal. The goal of these studies is to use high-anisotropy for writing nanoscale magnetic domains (‘bits’). The experiments demonstrate that ‘bit’ magnetization can be deterministically reversed by single optical laser pusles (publication in preparation).

 Using synchrotron radiation we have investigated the insulator-metal transition in VO2 in thermal equilibrium. o X-ray absorption measurements at the V-L edges at the ALS showed a novel control mechanism, the orbital occupancy, for the insulator-metal transition [1]. o X-ray absorption measurements at the V-L edges at the ALS showed that two phase transition occur sequentially: A weakening of electronic correlations preceedts the proper insulator-metal transitions and provides the first insight into the underlying mechanism [6].

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Magnetization & Dynamics FWP#: 10067

o Using Resonant Inelastic X-ray Scattering (RIXS) at the Swiss Light Source (SLS) we probed the evolution of the electronic excitations across the metal-insulator transition. In collaboration with theory groups data analysis is currently in progress.

 Using LCLS we have continued to investigate THz driven insulator-metal transition using x-ray scattering techniques: o Experiments at the XPP beamline in 2013 showed that the insulator-metal transition in VO2 can be driven by intense THz electic field pulses (publication in preparation). o In a second LCLS XPP experiment we systematically studied the THz driven insulator-metal transition in high-quality epitaxial VO2 films. The influence of the electric field orientation on the transition has been studied and the data analysis is currently ongoing. o We used THz radiation to drive spin dynamics in a prototypical ferrimagnet DyFeO to prepare for future LCLS beamtime applications [7].

 Following our first experiments at the LCLS SXR beamline aimed at demonstrating stimulated inelastic x-ray scattering in solid state samples we have performed a follow up experiment at the AMO beamline. The data analysis is currently in progress.

 We have used the LCLS SXR instrument to study the laser-induced non-equilibrium phase transition in FeRd films. Epitaxially grown FeRd films were found to display a spin tranition form an antiferromagnetic phase with spin oriented along the sample normal to an in-plane orientation characterized by ferromagnetic ordering. The LCLS results indicate that via resonant x-ray scattering we are able to observe the strongest force in magnetism, the exchange interaction, at work at shortest time and lengthscales. The data analysis is currently in progress.

 In collaboration with external groups we studied the orbital and spin moments of 5 to 11 nm Fe3O4 nanoparticles measured via x-ray magnetic circular dichroism [5].

Expected Progress in FY2015  Publications of Previous Experimental Results: One of the main focuses in the first half of FY15 is to publish results obtained by successful LCLS experiments performed in FY2014. This includes two most recent experiments at the SXR instrument on FeCoGd and FeRd, the XPP instruments on VO2 and the AMO instrument on developing stimulated x-ray scattering. Data analysis and theoretical analysis are in progress for preparing scientific manuscripts. In the meantime, we plan to present some of our results in several conferences and workshops.  We will continue to develop electric field induced switching of insulator-metal transitions using laboratory sources. Additionally the use of relativistic electron bunches at FACET will be studied. Beamtime at FACET has been granted and is ongoing.  Planned x-ray experiments: o SSRL: We will continue developing instrumentation for using the SSRL low-alpha mode where x-ray pulse durations can be reduced down to several ps. Commission experiments aiming at efficient detection schemes for the reduced low-alpha x-ray flux are planned. They will be used to study ultrafast spin transport phenomena in magnetic materials and laser induced insulator-metal transitions in correlated oxide materials. o We will use SSRL to investigate the propagation of spin currents in non-magnetic materials. Spin exchange promoted by the proximity of ferromagnetic and non-magnetic layers is currently a very active topic in spintronics. Out-of-equilibrium spin current promise a significant increase in transport efficiency. o LCLS: LCLS beamtimes at SXR for developing stimulated scattering and studying all optical switching have been granted. In addition beamtime at XPP is approved to develop our understanding about angular momentum transfer in magnetic materials following ultrafast laser excitation. The novel aspect that needs to be developed here is if angular momentum buildup in te lattice can be detected.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Magnetization & Dynamics FWP#: 10067

Expected Progress in FY2016 Activities at LCLS and SSRL will continue. We will extend activities to novel artificial layered materials that have recently been found to display all-optical magnetic switching behavior. Synchrotron and laser based cahraterization is underway and will continue hopefully culminating in further high-profile applications for LCLS beamtime.

Collaborations Bert Hecht (Wuerzburg Germany), Theo Rasing (Radboud University Nijmegen, NL), Mark Golden (University of Amsterdam, NL), Andy Kent (Columbia University), Stuart Parkin (IBM Almaden), Olav Hellwig (HGST), Keith Nelson (MIT), Rick Averitt (Boston Univiersity), Heidan Wen, John Freeland (APS, Argonne Nat. Lab.), Christian Schüssler-Langeheine (HZ Berlin, Germany, A. Scherz (XFEL, Germany), C. Back (U. Regensburg, Germany), E. Fullerton (UCSD).

st Publications for FY13 & FY14 (Oct 1 2012 to date) 1. Towards Wide Temperature Range Control of the Metal-Insulator Transition in Vanadium Dioxide by Modifying Orbital Occupancy, Nagaphani B. Aetukuri, Alexander X. Gray, Marc Drouard, Matteo Cossale, Li Gao, Alexander H. Reid, Roopali Kukreja, Hendrik Ohldag, Catherine A. Jenkins, Elke Arenholz, Kevin P. Roche, Hermann A. Dürr, Mahesh Samant, Stuart S.P. Parkin, Nature Physics 9, 661 (J2013). 2. Magnetic design evolution in perpendicular magnetic recording media as revealed by resonant small angle x-ray

scattering, Tianhan Wang, Virat Mehta, Yoshihiro Ikeda, Hoa Do, Kentaro Takano, Sylvia Florez, Bruce D. Terris, Benny Wu, Catherine Graves, Michael Shu, Ramon Rick, Andreas Scherz, Joachim Stöhr, Olav Hellwig, Appl. Phys. Let. 103, 112403 (2013). 3. The role of space charge in spin-resolved photoemission experiments, A Fognini, G Salvatella, T U Michlmayr, C Wetli, U Ramsperger, T Bähler, F Sorgenfrei, M Beye, A Eschenlohr, N Pontius, C Stamm, F Hieke, M DellʼAngela, S de Jong, R Kukreja, N Gerasimova, V Rybnikov, H Redlin, J Raabe, A Foehlisch, H A Dürr, W Wurth, D Pescia, A Vaterlaus, Y Acremann, New J. Phys. 16, 043031 (2014). 4. Ultrafast reduction of the total magnetization in iron, A. Fognini, T.U. Michlmayr, G. Salvatella, C. Wetli, U. Ramsperger, T. Baehler, F. Sorgenfrei, M. Beye, A. Eschenlohr, N. Pontius, C. Stamm, F. Hieke, M. Dell’Angela, S. de Jong, R. Kukreja, N. Gerasimova, V. Rybnikov, A. Al-Shemmary, H. (Redlin, J. Raabe, A. Foehlisch, H.A. Dürr, W. Wurth, D. Pescia, A. Vaterlaus, Y. Acremann, Appl. Phys. Lett. 104, 032402 (2014).

5. Orbital and spin moments of 5 to 11 nm Fe3O4 nanoparticles measured via x-ray magnetic circular dichroism, Y. P. Cai, K. Chesnel, M. Trevino, A. Westover, R. G. Harrison, J. M. Hancock, S. Turley, A. Scherz, A. Reid, B. Wu, C. Graves, T. Wang, T. Liu, H. Dürr, J. Appl. Phys. 115, 17B537 (2014) 6. Correlation-driven insulator-metal transition in near-ideal vanadium dioxide films, A. X. Gray, J. Jeong, N. P. Aetukuri, P. Granitzka, Z. Chen, R. Kukreja, D. Higley, T. Chase, A. H. Reid, H. Ohldag, M. Marcus, A. Scholl, A. T. Young, A. Doran, C. A. Jenkins, P. Shafer, E. Arenholz, M. G. Samant, S. S. P. Parkin, H. A. Dürr, Nature Materials, under external review (2014).

7. Terahertz-driven magnetism dynamics in DyFeO3, A. H. M. Reid, A. V. Kimel, Th. Rasing, R. V. Pisarev, H. A. Dürr, M. C. Hoffmann, submitted (2014).

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Atomic Engineering Oxide Heterostructures: Materials by Design FWP#: 10069 Atomic Engineering Oxide Heterostructures:

Materials by Design Principal Investigator(s): Harold Y. Hwang (FWP lead), Srinivas Raghu, Yasuyuki Hikita, Christopher Bell (until Oct. 2013) Staff Scientists: Jun-Sik Lee, Yanwu Xie, Hongtao Yuan Postdoctoral Scholars and Graduate Students: Zhuoyu Chen, Pavan Hosur, Hisashi Inoue, Bongju Kim, Di Lu, Akash Maharaj, Tyler Merz, and Hyeok Yoon Visiting Physicists: Satoshi Harashima (until April 2014), Hiroki Sato (until April 2014), Takashi Tachikawa

Overview The overarching scientific goals of this FWP are to use techniques we have developed for atomic-scale synthesis of complex oxide heterostructures to address the grand challenges for basic energy sciences. The issues we investigate are central to the challenge of “how do we atomically design and perfect revolutionary new forms of matter with tailored properties”, and which are also important to the challenges of controlling processes at the electron level, understanding and creating emergent phenomena, and mastering energy and information on the nanoscale. Keywords for this FWP are emergence, design, and engineering:  Emergence – how can we harness the strongly interacting charge, spin, orbital, and lattice degrees of freedom of transition metal oxides to create new states at their surfaces and interfaces, which exhibit properties beyond their bulk constituents?  Design – how can we use theory to transcend intuition and serendipity, and move towards the rational construction of materials at the atomic scale?  Engineering – how can we use the flexibility and reduced symmetry of oxide interfaces and surfaces to enhance their properties and band lineups for optimal use in energy technologies? X-ray scattering, spectroscopy, and microscopy are used to examine the surface and interface electronic structure, their nanoscale coupling, and their lateral nanoscale static and dynamic order. Magnetotransport and scanning probes are used to study artificial two-dimensional (2D) superconducting and magnetic oxide heterostructures, towards the development of the mesoscopic physics of d-electron systems. Advanced analytical and computational theory techniques are applied to develop a quantitative foundation for analysis and predictive design. In addition to the core mission of DoE BES, these aims are well aligned to the Materials Genome Initiative, and the Mesoscale Materials and Chemistry Initiative currently being developed.

Progress in FY2014

 Bilayer superconducting heterostructures based on delta-doped SrTiO3 have been systematically investigated both experimentally and theoretically. In terms of the angular variation of the upper critical field, systematic coupling between the superconductors has been observed, from the decoupled limit at wide separations, to increasing coupling on the length scale of the superconducting coherence length [Ref. 13 in publication list; DoE highlight submitted]. We investigated the role of multiple subband degrees of freedom and interlayer pair tunneling on the transition temperature. Furthermore, by moving to lower density higher mobility samples, we can observe well defined quantum oscillations in the magnetoresistance, by which we can extract the coupling of the normal state and directly compare to the superconducting state. This suggests a novel approach to designing multicomponent superconductivity using subband structure in quantum wells.  We developed new scaling theories of non-Fermi liquid metals [8, 12 (Editor’s Suggestion), 18, 19]. These theories are based on a proper renormalization group theory of interacting fermions near a quantum phase transition. Our theory predicts new pattern of universal properties such as the heat capacity behaving logarithmically as a function of temperature in 3 dimensions. Our theory also suggests that near a nematic quantum critical point, there is a significant tendency towards high temperature superconductivity.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Atomic Engineering Oxide Heterostructures: Materials by Design FWP#: 10069

 Several investigations of the unconventional state at the LaAlO3/SrTiO3 interface have been performed. By using top-gating [15], or surface charge/adsorbate control [14, 26], a new regime of low-density high-mobility electrons can be achieved. Most notably, we see the development of Hall plateau features in a regime of occupying a single light and single heavy subband [27]. We also measured the gate-bias dependent band alignment, especially the confining potential profile, at the conducting LaAlO3/SrTiO3 heterointerface using soft and hard x-ray photoemission spectroscopy [24]. Depth-profiling analysis reveals that a significant potential drop on the SrTiO3 side of the interface occurs within ~2 nm of the interface under negative gate bias voltage. These results demonstrate gate control of the collapse of permittivity at the interface, and explain the dramatic loss of electron mobility with back-gate depletion.  We investigated the effects of competing orders on unconventional superconductivity [10; Editor’s Suggestion]. Working in the weak-coupling limit where calculations can be reliably controlled, we showed the effect of several competing order phases – ranging from charge and spin density waves, to various types of nematic order – on both the superconducting pairing strength as well as on the pairing symmetry itself.  We have greatly extended our ability to engineer band alignments in oxide hetereostructures by designing interface dipoles which are inserted at the interface. Two forms have been investigated: the insertion of positive or negative charge layers where the dipole is completed by the induced screening charge [25], and the insertion of complete dipoles using polar inserts. These techniques have enabled the ability to experimentally tune band alignments by several eV.  We suggested that the partial ordered phase of MnSi exhibits anomalous properties due to the fact that fermionic quasiparticles scatter off of columnar spin textures [21], which may have been observed in the material. We made the suggestion that what was previously thought to be a “non-Fermi liquid phase” may instead be an “anomalous Fermi liquid” where well-defined quasiparticles exhibit a different scattering rate due to Berry phase effects associated with the magnetic textures present in the material.

 We put forward a new explanation for the substantially reduced edge currents in Sr2RuO4, a material that likely exhibts spin triplet chiral p-wave pairing [20]. We suggested that the boundaries of the material may be metallic in character in the presence of weak disorder, since the system is not an s-wave superconductor (there is significant evidence supporting this notion from STM measurements). We showed that the resulting superconducting-normal interface, if present in the material, would lead to electrical current response that is at least an order of magnitude smaller than naïve expectations based on a chiral p+ip superconductor terminating at a vacuum.  We have probed the evolution from interfacial charge compensation to metallic screening across the manganite (La,Sr)MnO3 metal-to-insulator transition at an interface polar discontinuity with n-type semiconducting SrTiO3 [17]. For this rectifying junction, we have measured the electrical properties (I-V, C-V) and spectroscopically (internal/core-level photoemission, electron energy-loss). A clear crossover is observed, corresponding to reconstructions of the polar discontinuity evolving to metallic screening and interface dipole formation. The total charge observed for the insulating manganite films quantitatively agrees with that needed to cancel the polar catastrophe. As the manganite becomes metallic with increased hole-doping, the total charge build-up and its spatial range drop substantially. Accompanying this transition is a systematic shift in the band alignment, which suggests the role of correlations as this Mott transition is traversed.  We suggested that hexagonal systems tuned close to van-Hove fillings can exhibit a tendency towards spin-orbital current phases [9]. We investigated models of fermions on triangular, honeycomb and Kagome lattices with short range repulsive interactions. We showed that in addition to the usual tendency towards ferromagnetism, there are additional instabilities where the spin and orbital degrees of freedom get coupled even in the absence of atomic spin- orbit coupling. Such phases are referred to as particle-hole condensates with higher angular momentum and spin.

Expected Progress in FY2015

Further theoretical study of unconventional superconductivity – examples include UGe2, URhGe, where ferromagnetism coexists with superconductivity, and Purple Bronze, which is likely to be a candidate spin triplet superconductor. Further theoretical study of the anomalous properties and spin textures of MnSi and related materials including FeSe. We will extend our work on bilayer superconductors to probe novel drag effects using nonlocal transport measurements, to examine the superconducting and vortex contributions to drag, in addition to Coulomb coupling. The use of both top and back gating SrTiO3 structures will be used to probe the complete 2D superconductor-insulator phase diagram for all

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Atomic Engineering Oxide Heterostructures: Materials by Design FWP#: 10069 regimes of disorder. Motivated by prior theoretical studies in this FWP, we will initiate attempts to refine the growth of (111)-oriented perovskite heterostructures, bilayers of which create a honeycomb lattice.

Expected Progress in FY2016 Further theoretical study of strongly enhanced superconducting instabilities near quantum critical points, the goal being to identify limits where higher Tc superconductivity can emerge from a non-Fermi liquid regime, the parametric enhancement of Tc and the effect of quantum critical fluctuations on the superfluid density. We will also study the pairing of composite fermions in a half-filled Landau level and describe the circumstances under which the pairing can have p+ip symmetry, as is thought to be the case in the 5/2 quantum Hall state. X-ray probes of magnetic reconstructions in ultrathin magnetic oxide films are planned, first to examine static properties, and eventually dynamical response. Increasing efforts to study magnetotransport in oxides on mesoscopic length scales are planned.

Collaborations T.H. Geballe, S. Kachru, A. Kapitulnik, S. Kivelson, K. A. Moler, Y. Cui, T. P. Devereaux, Z. X. Shen, H. Durr, J. Stohr, J. K. Norskov, A. Nilsson, M. Brongersma, C.-C. Kao, X. Qi (Stanford/SLAC); R. Thomale (ETF Lausanne); H. Akiyama, A. Fujimori, Y. Iwasa, M. Kawasaki, K. Miyano, N. Nagaosa, M. Oshima, S. Shin, H. Takagi, Y. Tokura (Tokyo); T. Kimura, Y. Wakabayashi (Osaka); H. Ohta (Nagoya); T. Egami, H. N. Lee (ORNL); J. Levy (Pittsburgh); Y. Taguchi (RIKEN); D. A. Muller, L. F. Kourkoutis, D. G. Schlom (Cornell); B. G. Kim (Pusan); B. Keimer, J. Mannhart (MPI Stuttgart); T. W. Noh (Seoul); C. Bernard (Fribourg); D. H. A. Blank, G. Rijnders (Twente); R. Ramesh (Berkeley); J. H. Song (Chungnam); A. F. Hebard (Florida); G. A. Sawatzky (UBC); T. Banerjee (Groningen); A. J. Millis (Columbia); F. Baumberger, J. M. Triscone (Geneva); S. J. Allen, D. D. Awschalom, C. Nayak, S. Stemmer, C. Van de Walle (UCSB); S. Rajan (Ohio State); D. Jena (Notre Dame); C. H. Ahn, T. P. Ma (Yale); Y. Dagan (Tel Aviv); J. Aarts, Y. M. Huber (Leiden); C. Attanasio (CNR-INFM); M. G. Blamire (Cambridge); B. Kalisky (Bar-Ilan); H. Kumigashira (KEK, Japan); M. Yu. Kupriyanov (Moscow State); V. N. Kushnir (Belarus State); W. Meevasana (Thailand Center of Excellence in Physics); R. J. Wijngaarden (Vrije).

Publications for FY13 & FY14 (Oct 1st 2012 to date)

Publications that were primarily supported by this FWP

1. S. Raghu, R. Thomale, and T.H. Geballe, "Optimal Tc of Cuprates: Role of Screening and Reservoir Layers," Phys. Rev. B 86, 094506 (2012). 2. T. Higuchi and H. Y. Hwang, “General Considerations of the Electrostatic Boundary Conditions in Oxide Heterostructures,” in Multifunctional Oxide Heterostructures, edited by E. Tsymbal, C. B. Eom, R. Ramesh, and E. Dagotto, pp. 183-213, Oxford University Press (2012). 3. S. Raghu, Suk Bum Chung, and Samuel Lederer, "Theory of 'Hidden' Quasi-One Dimensional Superconductivity in

Sr2RuO4", Proceedings of M2S 2012, Journal of Physics: Conference Series 449, 1 (2013). 4. P. Hosur, A. Kapitulnik, S.A. Kivelson, J. Orenstein, and S. Raghu, "Kerr Effect as Evidence of Gyrotropic Order in the Cuprates," Phys. Rev. B 87, 115116 (2013). 5. M. Hosoda, C. Bell, Y. Hikita, and H. Y. Hwang, “Composition and Gate Tuned Interfacial Conductivity in

LaAlO3/LaTiO3/SrTiO3 Heterostructures,” Appl. Phys. Lett. 102, 091601 (2013).

6. J.-S. Lee, Y. W. Xie, H. K. Sato, C. Bell, Y. Hikita, H. Y. Hwang, and C.-C. Kao, “Titanium dxy Ferromagnetism at

the LaAlO3/SrTiO3 Interface,” Nature Mater. 12, 703 (2013). 7. S. Harashima, C. Bell, M. Kim, T. Yajima, Y. Hikita, and H. Y. Hwang, “Coexistence of Two- and Three- + Dimensional Shubnikov-de Haas Oscillations in Ar -Irradiated KTaO3,” Phys. Rev. B 88, 085102 (2013). 8. R. Mahajan, D. Ramirez, S. Kachru, and S. Raghu, "Quantum Critical Metals in d=3+1," Phys. Rev. B 88, 115116 (2013). 9. A. Maharaj, R. Thomale, and S. Raghu, "Particle-Hole Condensates of Higher Angular Momentum in Hexagonal Systems," Phys. Rev. B 88, 205121 (2013). 10. W. Cho, R. Thomale, S. Raghu, and S. Kivelson, “Band-Structure Effects on Superconductivity in Hubbard Models,” Phys. Rev. B 88, 064505 (2013) [Editor’s Selection].

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Atomic Engineering Oxide Heterostructures: Materials by Design FWP#: 10069

11. S.-B. Chung, I. Mandal, S. Raghu, and S. Chakravarty, “Higher Angular Momentum Pairing from Transverse Gauge Interactions,” Phys. Rev. B 88, 045127 (2013). 12. A. L. Fitzpatrick, S. Kachru, J. Kaplan, and S. Raghu, “Non-Fermi Liquid Fixed Point in a Wilsonian Theory of Quantum Critical Metals,” Phys. Rev. B 88, 125116 (2013) [Editor’s Selection]. 13. H. Inoue, M. Kim, C. Bell, Y. Hikita, S. Raghu, and H. Y. Hwang, “Tunable Coupling of Two-Dimensional

Superconductors in Bilayer SrTiO3 Heterostructures,” Phys. Rev. B 88, 241104(R) (2013).

14. Y. W. Xie, C. Bell, Y. Hikita, S. Harashima, and H. Y. Hwang, “Enhancing Electron Mobility at the LaAlO3/SrTiO3 Interface by Surface Control,” Adv. Mater. 25, 4735 (2013). 15. M. Hosoda, Y. Hikita, H. Y. Hwang, and C. Bell, “Transistor Operation and Mobility Enhancement in Top-Gated

LaAlO3/SrTiO3 Heterostructures,” Appl. Phys. Lett. 103, 103507 (2013).

16. Y. W. Xie and H. Y. Hwang, “Tuning the Electrons at the LaAlO3/SrTiO3 Interface: From Growth to Beyond Growth,” Chinese Physics B 22, 127301 (2013). 17. J. A. Mundy, Y. Hikita, T. Hidaka, T. Yajima, T. Higuchi, H. Y. Hwang, D. A. Muller, and L. F. Kourkoutis, “Visualizing the Evolution from Interfacial Charge Compensation to Metallic Screening across the Manganite Metal-to-Insulator Transition,” Nature Commun. 5, 3464 (2014). 18. A. L. Fitzpatrick, S. Kachru, J. Kaplan, and S. Raghu, “Non-Fermi Liquid Behavior of Large N_B Quantum Critical Metals,” Phys. Rev. B 89, 165114 (2014). 19. A. L. Fitzpatrick, S. Kachru, S. Kivelson, J. Kaplan, and S. Raghu, “Slow Fermions in Quantum Critical Metals,” arxiv:1402.5413, Phys. Rev. Lett., submitted.

20. S. Lederer, W. Huang, E. Taylor, S. Raghu, and C. Kallin, “Suppression of Spontaneous Currents in Sr2RuO4 by Surface Disorder,” arXiv:1404.4637, Phys. Rev. B, submitted. 21. H. Watanabe, S. Parameswaran, S. Raghu, and A. Vishwanath, “Anomalous Fermi Liquid Phase in Metallic Skyrmion Crystals,” arXiv:1309.7047, Phys. Rev. B, submitted. 22. M. Kim, C. Bell, Y. Hikita, Y. Kozuka, B. G. Kim, and H. Y. Hwang, “Photoconductivity and Non-Exponential

Relaxation at Insulating LaAlO3/SrTiO3 Interfaces,” Sol. State Commun., in review. 23. M. Minohara, T. Tachikawa, Y. Nakanishi, Y. Hikita, L. Fitting Kourkoutis, M. Yoshita, H. Akiyama, C. Bell, and

H. Y. Hwang, “Atomically Engineered Metal-Insulator Transition at the TiO2/LaAlO3 Heterointerface,” Science, in review. 24. M. Minohara, Y. Hikita, C. Bell, H. Inoue, M. Hosoda, H. K. Sato, H. Kumigashira, M. Oshima, E. Ikenaga, and H.

Y. Hwang, “The Potential Profile at the LaAlO3/SrTiO3 (001) Heterointerface in operando Conditions,” Phys. Rev. Lett., in review. 25. T. Yajima, Y. Hikita, M. Minohara, C. Bell, H. Kumigashira, M. Oshima, and H. Y. Hwang, “Controlling Band Alignments by Artificial Interface Dipoles at Oxide Heterointerfaces,” Nature, submitted. 26. Y. W. Xie, Y. Hikita, C. Bell, and H. Y. Hwang, “Adsorbate-Induced Insulator-Metal Transition in Oxide Heterostructures,” Appl. Phys. Lett., in review. 27. Y. W. Xie, C. Bell, M. Kim, H. Inoue, Y. Hikita, and H. Y. Hwang, “Quantum Longitudinal and Hall Transport at

the LaAlO3/SrTiO3 Interface,” Phys. Rev. B (R), in review (arXiv: 1403.4343).

Collaborative publications supported by this FWP

1. E. Flekser, M. Ben Shalom, M. Kim, C. Bell, Y. Hikita, H. Y. Hwang, and Y. Dagan, “Magnetotransport Effects in

Polar versus Non-polar SrTiO3 Based Heterostructures,” Phys. Rev. B 86, 121104(R) (2012). 2. P. Munkhbaatar, N. Nakagawa, H. Y. Hwang, J. S. Kim, and K. Myung-Whun, “Effect of Anisotropic Strain on the

Charge Dynamics of Nd0.5Sr0.5MnO3 Thin Films,” Sol. State Commun. 152, 1541 (2012). 3. C. Bell, M. S. Bahramy, H. Murakawa, J. G. Checkelsky, R. Arita, Y. Kaneko, Y. Onose, M. Tokunaga, Y. Kohama, N. Nagaosa, Y. Tokura, and H. Y. Hwang, “Shubnikov-de Haas Oscillations in the Bulk Rashba Semiconductor BiTeI,” Phys. Rev. B 87, 081109(R) (2013). 4. K. G. Rana, T. Yajima, S. Parui, A. F. Kemper, T. P. Devereaux, Y. Hikita, H. Y. Hwang, and T. Banerjee, “Hot Electron Transport in a Strongly Correlated Transition Metal Oxide,” Scientific Reports 3, 1274 (2013).

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Atomic Engineering Oxide Heterostructures: Materials by Design FWP#: 10069

5. M. Sakano, M. S. Bahramy, A. Katayama, T. Shimojima, H. Murakawa, Y. Kaneko, W. Malaeb, S. Shin, K. Ono, H. Kumigashira, R. Arita, N. Nagaosa, H. Y. Hwang, Y. Tokura, and K. Ishizaka, “Strongly Spin-Orbit Coupled Two- Dimensional Electron Gas Emerging near the Surface of Polar Semiconductors,” Phys. Rev. Lett. 110, 107204 (2013). 6. S. Chakraverty, X. Yu, M. Kawasaki, Y. Tokura, and H. Y. Hwang, “Spontaneous B-Site Order and Metallic

Ferrimagnetism in LaSrVMoO6 Grown by Pulsed Laser Deposition,” Appl. Phys. Lett. 102, 222406 (2013). 7. Y. Yamada, H. K. Sato, Y. Hikita, H. Y. Hwang, and Y. Kanemitsu, “Extremely Slow Energy Relaxation of

Electrons at the LaAlO3/SrTiO3 Heterointerface,” Phys. Rev. Lett. 111, 047403 (2013). 8. H. Murakawa, M. S. Bahramy, M. Tokunaga, Y. Kohama, C. Bell, Y. Kaneko, N. Nagaosa, H. Y. Hwang, and Y. Tokura, “Detection of Berry’s Phase in a Bulk Rashba Semiconductor,” Science 342, 1490 (2013). 9. B. Kalisky, E. M. Spanton, H. Noad, J. R. Kirtley, K. C. Nowack, C. Bell, H. K. Sato, Y. W. Xie, Y. Hikita, C. Woltmann, G. Pfanzelt, R. Jany, H. Y. Hwang, J. Mannhart, and K. A. Moler, “Locally Enhanced Conductivity Due

to Tetragonal Domain Structure in LaAlO3/SrTiO3 Heterointerfaces,” Nature Mater. 12, 1091 (2013). 10. S. Chakraverty, T. Matsuda, N. Ogawa, H. Wadati, E. Ikenaga, M. Kawasaki, Y. Tokura, and H. Y. Hwang,

“BaFeO3 Cubic Single Crystalline Thin Film: A Ferromagnetic Insulator,” Appl. Phys. Lett. 103, 142416 (2013). 11. S. Bordacs, J. G. Checkelsky, H. Murakawa, H. Y. Hwang, and Y. Tokura, “Landau Level Spectroscopy of Dirac Electrons in a Polar Semiconductor with Giant Rashba Spin Splitting,” Phys. Rev. Lett. 111, 166403 (2013). 12. Y. Zhang, Y. F. Zhang, Q. Q. Ji, J. Ju, H. T. Yuan, J. P. Shi, T. Gao, D. L. Ma, M. X. Liu, Y. B. Chen, X. J. Song,

H. Y. Hwang, Y. Chui, and Z. F. Liu, “Controlled Growth of High-Quality Monolayer WS2 Layers on Sapphire and Imaging its Grain Boundary,” ACS Nano 7, 8963 (2013). 13. S. Chakraverty, T. Matsuda, H. Wadati, J. Okamoto, Y. Yamasaki, H. Nakao, Y. Murakami, S. Ishiwata, M. Kawasaki, Y. Taguchi, Y. Tokura, and H. Y. Hwang, “Multiple Helimagnetic Phases and Topological Hall Effect in

Epitaxial Thin Films of Pristine and Co-Doped SrFeO3,” Phys. Rev. B 88, 220405(R) (2013). 14. Y. Yamada, H. K. Sato, Y. Hikita, H. Y. Hwang, and Y. Kanemitsu, “Photocarrier Relaxation Dynamics in

LaAlO3/SrTiO3 Heterostructures,” Proc. SPIE 8987, 898710 (2014). 15. Y. Takahashi, S. Chakraverty, M. Kawasaki, H. Y. Hwang, and Y. Tokura, “In-plane Terahertz Response of Thin

Film Sr2RuO4,” Phys. Rev. B 89, 165116 (2014). 16. Y. Yamada, H. K. Sato, Y. Hikita, H. Y. Hwang, and Y. Kanemitsu, “Spatial Density Profile of Electrons near the

LaAlO3/SrTiO3 Heterointerface Revealed by Time-Resolved Photoluminescence Spectroscopy,” Appl. Phys. Lett. 104, 151907 (2014). 17. H. T. Yuan, Y. Ishida, H. Shimotani, X. Liu, K. Koizumi, K. Akaike, K. Kanai, Y. Kubozono, M. Brongersma, Y. Cui, H. Y. Hwang, M. Kawasaki, S. Shin, and Y. Iwasa, “Rational Design of Interfacial Energy Alignment in Functionalized Liquid/Solid Heterostructures,” Nature Mater., in review. 18. Y. Lei, Y. Z. Chen, Y. W. Xie, S. H. Wang, Y. Li, J. Wang, B. G. Shen, N. Pryds, H. Y. Hwang, and J. R. Sun,

“Visible Light Enhanced Field Effect at the LaAlO3/SrTiO3 Interface,” Nature Mater., in review. 19. T. Tsuyama, T. Matsuda, H. Wadati, S. Chakraverty, J. Okamoto, E. Ikenaga, A. Tanaka, T. Mizokawa, H. Y. 4+ Hwang, and Y. Tokura, “X-Ray Spectroscopic Study of BaFeO3 Thin Films; a Fe Ferromagnetic Insulator,” Phys. Rev. B (R), submitted. 20. Z. Erlich, Y. Frenkel, J. Drori, Y. Shperber, C. Bell, H. K. Sato, M. Hosoda, Y. W. Xie, Y. Hikita, H. Y. Hwang,

and B. Kalisky, “Optical Study of Tetragonal Domains in LaAlO3/SrTiO3,” J. Supercond. and Novel Magnetism, in review. 21. H. T. Yuan, B. Zhou, G. Xu, Z. K. Liu, S. F. Wu, D. Dumcenco, K. Yan, Y. Zhang, S.-K. Mo, P. Dudin, V. Kandyba, M. Yablonskikh, A. Barinov, Z. X. Shen, S. C. Zhang, Y. S. Huang, X. D. Xu, Z. Hussain, H. Y. Hwang, Y. Cui, and Y. L. Chen, “Electronic Structure Evolution between Different Transition-Metal Chalcogenides from Bulk to the Monolayer Limit,” Nature Mater., in review. 22. H. T. Yuan, X. Q. Wang, B. Lian, H. Zhang, X. Fang, B. Shen, G. Xu, Y. Xu, S. C. Zhang, H. Y. Hwang, and Y.

Cui, “Generation and Electric Control of Spin-Coupled Valley Current in WSe2,” Nature Nanotech., in review (arXiv: 1403.2696).

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Atomic Engineering Oxide Heterostructures: Materials by Design FWP#: 10069

23. B. Zhou, Z. K. Liu, S. H. Yao, H. T. Yuan, Y. Zhang, M. H. Lu, Y. F. Chen, X. Dai, Z. Fang, Y. Cui, H. Y. Hwang, Z. Hussain, Z. -X. Shen, S.-K. Mo, and Y. L. Chen, “Unusual In-Gap and Hybridized States of a Topological Kondo

Insulator Candidate, SmB6,” Scientific Reports, in review.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 High Energy Density Science at the SLAC National Accelerator Laboratory FWP#: 100182 High Energy Density Science at the SLAC National Accelerator Laboratory

Principal Investigator(s): Siegfried Glenzer

Staff Scientists: Luke Fletcher and Sebastian Goede Postdoctoral Scholars: Eliseo Gamboa, Maxence Gauthier, Rohini Mishra, and William Schumaker Fellows: Philipp Sperling and Christian Rödel Visiting Physicists: Alessandra Ravasio, Gianluca Gregori, Wojtek Rozmus, and Ying Tsui Visiting Graduate Students: Michael MacDonald and Daniel Cuballa

Overview:

This FWP requests support for the recently established High Energy Density (HED) science group at the SLAC National Accelerator Laboratory. The FWP for this program started at the beginning in fiscal year 2014. The requested support is for scientific personnel and equipment to perform pioneering research using HED science facilities including the Matter in Extreme Conditions (MEC) station at LCLS. The experiments within this program will develop a new research area where matter heated by powerful ultra-short pulse laser pulses will be directly interrogated with the LCLS x-ray beam and vice versa. This program will develop new targets and measurement techniques for ultra short pulse laser interaction experiments, perform the experiments, analyze the data, and disseminate the results.

Progress in FY2014

1. Experimental schedule and plan

By the end of FY2014, the HED program will have led/co-investigated 7 x-ray experiments at MEC/LCLS. The detailed experimental schedule for upcoming Q3-4, 2014 experiments is shown in Figure 1. Not shown are a total of 4 x-ray campaigns that have occurred since the end of FY13/beginning of FY14. For the remainder of FY14, the group will be collaborating on 3 experimental x-ray campaigns at MEC/LCLS. In summary, the 7 campaigns investigate the following research areas:

1. First demonstration of plasmon x-ray Thomson scattering measurements with a seeded x-ray beam in shock-compressed Al (L700, Glenzer, Apr 2013). 2. Measurements of the structure of shock and ramp-compressed diamond and Magnesium- oxide (LA61, Glenzer, Oct 2013). 3. X-ray Thomson scattering measurements of the plasmon dispersion in solids (in house beam time, Lee, Dec 2013). 4. Measurements of imaging x-ray Thomson scattering in shock-compressed matter (in house beam time, Lee, March 2014). 5. Structure measurements using wave-number resolved x-ray scattering on shock-compressed graphite (LD54, Kraus, May 2014). 6. Two-color plasmon x-ray Thomson scattering on x-ray heated matter (LC21, Barbrel, June 2014). 7. X-ray imaging of hot-electron propagation in high-power short-pulse laser heated solids (LC65, Galtier, Jul/Aug 2014).

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 High Energy Density Science at the SLAC National Accelerator Laboratory FWP#: 100182

The HED program will also lead/co-investigate 3 laser-only experiments at MEC/LCLS. These 3 campaigns are investigating the following research areas:

8. Precision shock velocity measurements in shock/ramp-compressed diamond using VISAR measurements on step targets (L01, Glenzer, May 2013). 9. Time-slot available for either a) high-power laser heating of cryogenic hydrogen jet plasmas or b) continuum lowering in compressed Al (L02, Glenzer, Aug 2013). The choice of experiment will be contingent on readiness. 10. Demonstration of a high-power laser produced betatron source from a laser wakefield accelerator in the blow-out regime (L03, Albert, Sep/Oct 2014).

Figure 1. Experimental Schedule, Q3/4, FY2014.

The science goals of the program will further be supplemented by experiments in collaboration with principal investigators on other user facilities including Omega through the laboratory basic science program, the Titan laser at Lawrence Livermore National Laboratory, and the Astra-Gemini laser at the Rutherford Appleton Laboratory, UK. Specifically, these experimental campaigns have the following goals:

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted:: 6/23/2014 High Energy Density Science at the SLAC National Accelerator Laboratory FWP#: 100182

11. Investigation of an electride structure in compressed Mg using x-ray scattering (Omega, Ma, April 2014) 12. Demonstration of a high-power laser produced betatron source from a laser wakefield accelerator in the linear acceleration regime (Titan, Albert, June 2014). 13. Investigation of proton stopping power in plasmas (Titan, Fuchs, July 2014). 14. Betatron pump-probe studies of x-ray absorption spectra in shock-compressed matter (Astra- Gemini, Mangles, Aug/Sep 2014)

2. Results from LCLS x-ray experiments

The past four experimental campaigns have been tremendously successful. After the demonstration of the first plasmon scattering data at LCLS on shock-compressed aluminum in April 2013, the technique has been also applied to shock-compressed boron-nitride and graphite targets during the same experiment. The first publication on the plasmon scattering technique has been published in the Journal of Instrumentation and one high-profile paper on x-ray seeding, plasmon scattering and simultaneous wavenumber resolved scattering data, and the phase diagram of aluminum has been submitted to Nature Materials.

Figure 2. (left) Wavenumber reolved x-ray scattering data and theoretical fits showing (bottom to top) the Bragg scattering features from cold aluminum, compressed solid aluminum, compressed aluminum in the coeexistence regime (solid and liquid), shocked aluminuum to a dense ionic fluid, and high-density plasma state at shocck coalescence. (Right) The total experimmental pressure data are shown as function of the measureed density. The data agree with empirically- known Hugoniot cruves and DFT-MD simulations. At shock coalescence, the data approach approach an isotherm and show agreement with DFT-MD simulations that were performed for the measured densities and temperatures. We observe a horizontal melt line at 1.2 Mbar. These data were taken on L700.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 High Energy Density Science at the SLAC National Accelerator Laboratory FWP#: 100182

A second high-profile paper on ionization in shock-compressed boron-nitride is presently in preparation. The graphite data will be used in conjunction with a paper on diamond.

Figure 2 provides a summary of data taken from shock-compressed Al. While the density has been obtained from plasmons the wavenumber resolved data provide pressure and material phases. The pressure values are in excellent agreement with density functional theory molecular dynamics simulations, and the melting line obtained from Bragg scattering features show a horizontal curve up to a density of 4.7 g/cc along the isotherm.

Figure 3. CVD diamond material strength from LCLS experiment LA61.

Our second LCLS campaign was performed parasitically with experiments at XPP, which constrains the experiment to use a SASE x-ray beam. Consequently, the experiment was not suitable for measuring plasmons and the experimental configuration was optimized to investigate the properties of shock- and ramp- compressed CVD diamond. Diamond is an important material that is utilized as ablator in inertial confinement fusion experiments, in diamond anvil cells in high-pressure material science research, and considered as an important material for planetary research. By observing multiple Bragg peaks with lattice parameters along and angular to the shock direction, we were able to measure the material strength to record values of 500 GPa. Figure 3 demonstrates high material strength of 200 GPa at the highest stress values reached in this study. These data extend the regime of previously known strength to conditions of the first shock in inertial confinement fusion implosions with CVD ablators. On the lower pressure range, we also verified that our strength data agree with measurements in diamond anvil cells (<200 GPa). This work forms the basis for a new LDRD proposal and is presently being prepared for dissemination.

During an in-house experiment led by H.-J. Lee, our team was successful in measuring the plasmon dispersion in aluminum, magnesium, and CVD. These materials were heated by the x-ray beam itself and plasmons measured with forward x-ray scattering spectra have been observed as function of scattering angle. Despite the fact that Al and Mg are both expected to behave like ideal metals we found remarkable differences in the scattering spectra especially at the transition region between collective plasmon scattering and non-collective Compton scattering. These differences are presently still being analyzed. Also remarkable is the fact that all three materials show a very weak plasmon dispersion due to strong local field corrections. Figure 4 shows an example of scattering spectra in diamond. The Al and Mg data served as a basis for a new proposal to make these measurements in shock-compressed matter at around 1 Mbar where local field corrections should be weak and the dispersion should approach predictions for an ideal Fermi-degenerated plasma. These CVD data are being compared with plasmon data from compressed diamond and will allow us to

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 High Energy Density Science at the SLAC National Accelerator Laboratory FWP#: 100182

study the optical response and physical properties of diamond at high pressure. Development of these techniques is important for possivle future studies of diamond irradiated by a more powerful nanosecond laser shock driver (for example from a pump laser for a future PW laser). It will allow probing of the interesting coexistence regime at pressures closer to 10 Mbar and the formation of a dense plasmas state.

Figure 4. Plasmon from CVD diamond measured as function of scattering angle in in-house beam time, Lee. The plasmon strength and width increases with larger angle while the energy shift is increasing only by 6 eV indicating weak dispersion. These data along with similar measurements in Al and Mg are presently being analyzed and prepared for dissemination.

As recently as March 2014, a second in-house experiment led by H.-J. Lee, delivered successful measurements of spatially resolved x-ray Thomson scattering spectra from shock-compressed graphite. For this purpose new imaging spectrometers have been fielded that provide spatial resolution of 10 micrometer sufficient to resolve shock propagation in compressed solids using couter-propagating laser geometry.

3. Development of HED capabilities

In addition to new already approved upgrades of the high-power laser systems at MEC, the scientific program in HED physics will need new developments of theory/simulations, targets and diagnostics. This multi-year effort will support new experimental campaigns at MEC and the development of the science case for PW laser experiments.

Theory and Simulations

To make predictions of future high-power laser experiments at MEC we have begun to employ particle-in-cell (PIC) simulations. We chose the multi-dimensional fully relativistic PIC code PICLS, developed by Y. Sentoku and A. Kemp, that allows computing realistic problems with plasma dimensions of some tens of micrometers and time durations of hundreds of femtoseconds. This tool runs in a massively parallel computer environment and accounts for non-linear and kinetic physics of intense laser-matter interactions by providing a fundamental kinetic plasma model as an ensemble of charged particles. The PIC code self-consistently solves the relativistic equations of motion for a large number of particles together with Maxwell’s equations. This is achieved through calculations of the trajectories of up to 1010 macro particles – each representing large numbers of physical electrons and ions – that are accelerated by electric and magnetic fields are averaged over the cells.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted:: 6/23/2014 High Energy Density Science at the SLAC National Accelerator Laboratory FWP#: 100182

Importantly, PICLS has atomic physics models such as relativistic Coulomb collisions, ionizations, and x-ray radiation. The ionization calculation includes two most dominant ionization mechanisms, field ionization (tunneling ionization), and collisional ionization. In addition, photo ionization is currently being implementing by solving the X-ray transport on top of the PIC calculation. The PICLS code has been consistently benchmarked against experiments. In the future, other codes will be considered as well, especially Osiris and LPL3D.

Figure 5. Results from particle in cell simulations show a laser-driven high-energy proton beam with >300 MeV at the optimized target density of ne/nc = 0.06 with nc=1.1 x 1021 cm-3/ (m) and  being the wavelength of the laser. (MeV) The laser is irradiating a 2 m diameter hydrogen target 20 -2 E_proton_ne_2e2 and the laser intensity iss 2 x 10 W ccm . Energy

Density (ne/nc) Figure 5 shows an example of a recent prediction of a novel laser proton acceleration regime. The proton energy for thin hydrogen targets irradiated by high-power lasers reach energies of great interest for isochoric heating or radiography. This simulation capability is presently also utilized to prepare experiments at lower intensities for studies of conductivity in cryogenic hydrogen targets.

Diagnostics

With the new high-power laser capabilities it is important to develop and field new diagnostics in the areas of proton beams, energetic electrons beams and betatron x-ray measurements. In FY2014, we will primarily employ our new image plate diagnostic that can be used for a direct detection of high- energy x-rays and protons.

Targets

In FY2014 we will field multiple types of solid targets including coated foil targets, step targets and Al dot targets. An example of a new step target design for precision shock velocity measurements in CVD diamond is shown in Fig. 6. This design will allow us to measure shock velocities between 10 and 20 km/s with accuracy of 1 km/s.

Figure 6. (Left) Step target design for CVD diamond. These targets will be shot at MEC as a laser only experiment to characterize shock velocities for laser pulse shapes that were used in LA61.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 High Energy Density Science at the SLAC National Accelerator Laboratory FWP#: 100182

Expected Progress in FY2015

1. Experimental schedule and plan

For FY2015, the HED program will propose 6 x-ray experiments and 2 laser-only experiments at MEC/LCLS. The detailed experimental schedule for upcoming 2015 is still being developed. In addition to these activities, shots at energetic laser facilities such as the Omega laser, the Titan laser, and the NIF are being proposed. A proposal will also be developed for the FLASH free electron laser.

2. Development of HED capabilities

Theory and Simulations In FY2015, our simulations capability that use particle-in-cell (PIC) codes will be expanded. In particular, we proposed a new project on NERSC where we will perform three-dimensional many- particle simulations to explore novel laser-plasma interaction regimes for proton and alpha particle acceleration. These studies will design future acceleration experiments where high-power lasers that interact with cryogenic hydrogen or helium targets. Preliminary 1D simulations, performed using the fully relativistic particle-in-cell code PICLS, show a unique regime of proton acceleration, e.g. ~ 300 MeV peak energy protons are observed in the interaction of a ~1020 W/cm2, 110fs intense laser with 21 -3 6nc dense (nc=10 cm ) and 2 m thin targets. The target becomes relativistically under-dense for the laser and we observe that a strong (multi-terawatt) shock electric field is produced and protons are reflected to high velocities by this field. Further, the shock field and the laser field keep propagating through the hydrogen target and soon meet up with the electric field produced at the target rear edge and vacuum interface. This super-position results in a powerful acceleration field that continues to accelerate ions to very high energies as they co-propagate along with the field behind the target. This mechanism is sensitive to target thickness and laser and target density conditions.

In the proposed project, we will perform a detailed investigation with 2D and 3D PICLS simulations to model realistic experimental scenarios and to gain insight into the physical processes. We expect that multidimensional effects will be important to make quantitative predictions and to optimize the proton acceleration mechanism.

For radiation-hydrodynamic studies we will continue to use the HELIOS code. In addition, we will explore possible alternate design codes such as Flash or Hydra.

Diagnostics

In FY2015 we will develop the capability for proton beam energy spectra measurements. We will evaluate two techniques, a magnetic spectrometer (Thomson parabola) and a second based on the time-of-flight technique, using a scintillator and photomultiplier tube. We expect to field one technique on MEC. Spatially resolved proton or electron beam images will be measured using radiochromic films (RCF) and image plate detectors.

For x-ray measurements, we will design and field new X-ray spectrometers in the 800 – 1000 eV and 1500 to 2200 eV spectral ranges to observe beam-induced K-shell emission in solids and gases. In

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted:: 6/23/2014 High Energy Density Science at the SLAC National Accelerator Laboratory FWP#: 100182 addition, we will begin developing high-energy bremsstrahlung spectrometers, filtered x-ray pinhole imaging and small-angle scattering.

The combined high-power laser and x-ray capabilities will enable measurements of current and density filaments through near forward imaging of the LCLS x--ray beam. An example of the proposed diagnostic and geometry is shown in Fig. 7. The LCLS and short-pulse laser beams will be co-timed to <100 fs and the LCLS beam will be focused such thaat the beam diameter is ~ 50 μm when it intersects the filaments in the plasma. Due to wavelength of the x-ray beam and the micron scale length of the density filaments, information of the structure of the filaments will be encoded onto x-rays scattered at small angles of ~ 0.17 mrad. This necessitates a large separation distance, labeled in Fig. 7 as X, between a carbon foam target and a pnCCD detector. The separation distance at which the signal from scattered x-rays can be angularly resolved from the transmitted laser beam is expected to be 2-5 meters.

Figure 7. Sketch of the ultrafast small-angle scattering technique, that provides information of the microns scale fluctuation induced by the short pulse laser.

Targets

For solid and machined targets, the development of a number of standard platforms is being pursued using target fabrication at Michigan, GA and LLNL. For targets with materials used in fusion research, on the other hand, we are pursuing an in-house program with the goals to provide high- repetition rate cryogenic jets of hydrogen, helium and mixtures. Figure 8 shows an example of a jet experiment that was performed in collaboration with Rostock and Jena at DESY.

Figure 8. Image of steady-state hydrogen jet with a diameter of 20 m is shown. The jet expands into vacuum with a speed of 100 m/s, operates for several hours and is suitable for laser-matter interaction experiments at high-repetition rate.

The preparation of the jet targets and diagnostics will begin in FY2015 in a new staging laboratory in sector 10 before fielding at MEC. The development will occur in 4 steps of increasing complexity:

(1) Steady-state hydrogen jet of 100m/s propagation speed with beam diameters of 20-50 m for studies of conductivity, equation off state, and collision less shock formation at liquid density.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 High Energy Density Science at the SLAC National Accelerator Laboratory FWP#: 100182

(2) Hydrogen jets with extremely small diameters of <5 m for studies of laser-driven proton beams at variable densities generated by laser pre pulses.

(3) Hydrogen micro-droplets and clusters for development of particle sources.

(4) Development of helium jets, helium-hydrogen jets, and water jets for studies of stopping powers and the equation of state of fusion plasmas.

Expected Progress in FY2016

In FY2016, we expect to have made major progress in the following areas:

1. Plasmon dispersion and damping in compressed matter 2. Material strength 3. High-pressure phase transitionns 4. New material phases at high pressures 5. Isochoric heating of matter 6. Isentropic heating of matter 7. Proton beam generation and characterization 8. Betatron generation 9. Continuum lowering

Collaborations 1. R. W. Falcone, B. Barbrel, D. Kraus Physics Department, University of California Berkeley, Berkeley, CA 94709, USA. 2. T. Döppner, S. LePape, T. Ma, M. A. Millot, A. Pak, D. Turnbull, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551, USA. 3. D. A. Chapman, D. O. Gericke, Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL, UK. 4. J. Vorberger, Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, 01187 Dresden, Germany. 5. T. White, G. Gregori, University of Oxford, Parks Road, Oxford, OX1 3PU, UK. 6. M. Wei, General Atomics, San Diego, CA. 7. U. Zastrau, Institute for Optics and Quantum Electronics, Friedrich-Schiller-University 07743 Jena, Germany, 8. P. Neymayer, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1 64291 Darmstadt, Germany.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 High Energy Density Science at the SLAC National Accelerator Laboratory FWP#: 100182

Publications for FY13 & FY14 (Oct 1st 2012 to date) Peer-Reviewed Journal Articles 1. Observations of Continuum Depression in Warm Dense Matter with X-Ray Thomson Scattering, L. B. Fletcher, A. L. Kritcher, A. Pak, T. Ma, T. Döppner, C. Fortmann, L. Divol, O. S. Jones, O. L. Landen, H. A. Scott, J. Vorberger, D. A. Chapman, D. O. Gericke, B. A. Mattern, G. T. Seidler, G. Gregori, R. W. Falcone, and S. H. Glenzer, Phys. Rev. Lett. 112 145004 (2014).

2. Resolving Ultrafast Heating of Dense Cryogenic Hydrogen, U. Zastrau, P. Sperling, M. Harmand, A.

Becker, T. Bornath, R. Bredow, S. Dziarzhytski, T. Fennel, L. B. Fletcher, E. Förster, S. Göde, G.

Gregori, V. Hilbert, D. Hochhaus, B. Holst, T. Laarmann, H. J. Lee, T. Ma, J. P. Mithen, R. Mitzner, C.

D. Murphy, M. Nakatsutsumi, P. Neumayer, A. Przystawik, S. Roling, M. Schulz, B. Siemer, S.

Skruszewicz, J. Tiggesbäumker, S. Toleikis, T. Tschentscher, T. White, M. Wöstmann, H. Zacharias, T.

Döppner, S. H. Glenzer, and R. Redmer, Phys. Rev. Lett. 112 105002 (2014).

3. Angular Dependence of Betatron X-Ray Spectra from a Laser-Wakefield Accelerator, F. Albert, B. B. Pollock, J. L. Shaw, K. A. Marsh, J. E. Ralph, Y.-H. Chen, D. Alessi, A. Pak, C. E. Clayton, S. H. Glenzer, and C. Joshi, Phys. Rev. Lett. 111 235004 (2013).

4. Plasmon measurements with a seeded x-ray laser, L.B. Fletcher, E. Galtier, P. Heimann, H.J. Lee, B. Nagler, J. Welch, U. Zastrau, J.B. Hastings, and S.H. Glenzer, J. Instrumentation 8 C11014 (2013).

5. Exploring the high-pressure properties of aluminium with an ultra-bright seeded x-ray laser, L. B. Fletcher, H. J. Lee, T. Döppner, E. Galtier, B. Nagler, P. Heimann, C. Fortmann, S. LePape, T. Ma, M. A. Millot, A. Pak, D. Turnbull, D. A. Chapman, D. O. Gericke, J. Vorberger, T. White, G. Gregori, M. Wei, B. Barbrel, R. W. Falcone, C.-C. Kao, H. Nuhn, J. Welch, U. Zastrau, J. B. Hastings and S. H. Glenzer, Nature Materials (under review).

Journal Articles

6. User Workshop on High-Power Lasers at the Linac Coherent Light Source, Roger Falcone, Siegfried Glenzer & S. Hau-Riege Synchrotron Radiation News, Vol. 27, No. 2, 2014.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: : Nanostructured Design of Sulfur Cathodes for High Energy Lithium-Sulfur Batteries FWP#: 100185 Nanostructured Design of Sulfur Cathodes for High Energy Lithium-Sulfur Batteries Principal Investigator(s): Yi Cui Postdoctoral Scholars and Graduate Students: Wei Liu, Jie Sun, Yongming Sun, Jung Ho Yu

Overview The EERE Vehicle Technology Program has supported research in high-energy lithium-based battery technologies for plug-in-hybrid-electric (PHEV) and electric vehicles (EV), calling for high capacity electrode materials. In this project, we will conduct research on developing sulfur cathodes from the perspective of nanostructured materials design, which will be used to combine with lithium metal anodes to generate high-energy lithium-sulfur batteries. Specifically, we will study the fundamental of lithium-sulfur reaction and design sulfur nanostructures and multifunctional coating to overcome the issues related to volume expansion, polysulfide dissolution and insulating nature of sulfur. We aim to enable high capcity and long cycle life sulfur cathodes.

Progress in FY2014

In our group's previous study, we showed the fabrication of TiO2-coated sulfur yolk-shell nanostrucures and polyvinylpyrrolidone (PVP)-encapsulated hollow sulfur nanospheres for sulfur cathode, which could improve the cycling stability due to the void space engineered into the TiO2 or PVP shell to accommodate the sulfur volume expansion. However, the rate capability of the batteries still needs further improvement due to the nonconductive TiO2/PVP shells on the surfaces of sulfur particles. In order to improve the rate performance of lithium-sulfur batteries, we demonstrated stable and high performance sulfur cathodes made from conductive polymer-coated hollow sulfur nanospheres. Polyaniline (PANI), polypyrrole (PPY), and poly(3,4-ethylenedioxythiophene) (PEDOT), three of the most well-known conductive polymers were coated, respectively, onto monodisperse hollow sulfur nanopsheres through a facile, versatile, and scalable polymerization process in aqueous solution at room temperature. We systematically investigated how coating thickness and conductivity of these polymers affected the electrochemical properties of sulfur electrodes. We found that the ability of these three conductive polymers in enabling long cycle life and high-rate performance decreased in the order of PEDOT > PPY > PANI. At 0.5C rate, the cells made from PANI-, PPY-, and PEDOT-encapsulated sulfur nanospheres delivered high initial discharge capacities of 1140, 1201, and 1165 mAh/g, respectively. After 500 discharge/charge cycles at 0.5C, the cells made from PEDOT- and PPY-encapsulated sulfur particles still delivered high reversible capacities of 780 and 726 mAh/g, respectively (a decay of only 0.066% and 0.08% per cycle). Even at high current of 4C, a capacity of 624, 440, and 329 mAh/g can be achieved for the cells made from PEDOT-, PPY- and PANI-coated sulfur particles, respectively. We also performed ab initio simulations to elucidate the significance of chemical bonding between these conductive polymers and LixS (0

Expected Progress in FY2015-2016

We will continue to develop encapsulation methods for S particles to have polysulfides dissolution less than 10%. We will quantity the S-based chemical species spational distribution and design strategy to harvest as much S-based species as possible. We plan to study the electrical conductivity of S-based species deposited on solid substrate and identify any critical size for activation.

Collaborations 1. None

Publications for FY13 & FY14 (Oct 1st 2012 to date) Peer-Reviewed Journal Articles 1. Li, W.; Zhang, Q.; Zheng, G.; Seh, Z. W.; Yao, H.; Cui, Y. Nano Lett., 2013, 13 , 5534–5540.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 SIMES: Pre-Lithiation of Silicon Anode for High Energy Li Ion Batteries FWP#: 100186 Pre-Lithiation of Silicon Anode for High Energy Li Ion Batteries Principal Investigator(s): Yi Cui Postdoctoral Scholars and Graduate Students: Weiyang Li, Zheng Liang, Zhenda Lu, Kai Yan, and Jie Zhao

Overview Prelithiation of high capacity electrode materials such as Si is an important means to enable those materials in high- energy batteries. Here we explore several methods of prelithiation in order to understand their impact on the electrochemical property and cyclability of Si anodes. We aim to identify the best and most practical prelithiation methods.

Progress in FY2014

Rapid progress has been made in realizing battery electrode materials with high capacity and long-term cyclability in the past decade. However, the low first cycle Coulombic efficiency, as a result of the formation of solid electrolyte interphase and lithium trapping at the anodes, remains unresolved. In 2013-2014, we developed LixSi-Li2O core-shell nanoparticles that afford an excellent prelithiation reagent with high specific capacity to compensate for the first cycle capacity loss. These nanoparticles are produced with a facile and scalable synthesis approach by direct alloying of Si nanoparticles with Li metal foil. LixSi-Li2O core-shell nanoparticles (NP) are compatible with conventional slurry process and exhibit high capacity under dry air conditions with the protection of Li2O passivation shell. Using 1,3- dioxolane or toluene as the slurry solvent, LixSi-Li2O nanoparticles show high extraction capacities of 1200-1400 mAh/g, which is sufficient as the prelithiation reagent. After exposure to dry air for one day, there is 1175 mAh/g capacity, only 9% decay from time zero, indicating the LixSi-Li2O core-shell NPs are compatible with the whole battery fabrication process in the dry room. LixSi-Li2O NPs, exposed to dry air for 5 days, remain active and able to prelithiate MCMB graphite, which yields 20% improvement in 1st cycle Coulombic efficiency, indicating the potential of long-term storage. Both Si and graphite anodes are successfully prelithiated with these nanoparticles to achieve high 1st cycle Coulombic efficiencies of 94% to 99%. The undesired consumption of Li from cathode materials is suppressed during SEI formation. This approach is generally applicable to various anode materials involving complex nanostructures. The LixSi-Li2O core-shell nanoparticles enable practical implementation of high-performance electrode materials in lithium ion batteries.

Expected Progress in FY2015-2016

We will continue to develop LixSi nanoparticles for prelithiation. The target is to develop a scalable synthesis method of producing these particles, to further improve prelithiation capacity, to develop coating techniques to make them stable in the humidity level of battery electrode coating room and eventually in the ambient condition for 5hrs. We will continue to evaluate these particles blended with Si and carbon anodes.

Collaborations None.

Publications for FY13 & FY14 (Oct 1st 2012 to date) Peer-Reviewed Journal Articles

1. J. Zhao, Z. Lu and Y. Cui, Dry-air Stable LixSi-Li2O Core-shell Nanoparticles as High Capacity Prelithiation Reagents, manuscript in review.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 MEC User Workshop on High-Power Lasers FWP#: 100189 MEC User Workshop on High-Power Lasers

Principal Investigator(s): Siegfried Glenzer Staff Scientists: William White (SLAC Visiting Scientists: Roger Falcone (LBNL),Stefan Hau-Riege (LLNL), Alexander Tomas (University of Michigan), Mingsheng Wei (General Atomics)

Overview:

This workshop brings together the international science community to discuss the unique physics opportunities enabled by the new 200 TW laser at the Linac Coherent Light Source (LCLS). Coupling this laser to the world-class LCLS x-ray beam at the recently commissioned Matter in Extreme Condition (MEC) instrument allows exquisite pump-probe experiments to address the most important physics questions of high-power laser plasma interactions physics in areas of high-energy density physics, laboratory astrophysics, laser-particle acceleration, and non-linear optical science.

The workshop highlights recent results from MEC, describes the scientific opportunities for laser experiments at 200 TW and PW power and presented and discusses the user access policy for performing laser experiments at MEC.

Please see the High-Power Laser Workshop website: http://conf-slac.stanford.edu/hpl-2013/

Progress in FY2014

A two-day international workshop on the physics and integration of high-power lasers with the Linac Coherent Light Source was held in Stanford, USA, on October 1-2, 2013. The workshop was co-organized by UC Berkeley, Lawrence Berkeley, Lawrence Livermore and SLAC National Accelerator Laboratories. More than 150 scientists, including 30 students and postdocs who are working in high-intensity laser-matter interactions, fusion research, and dynamic high- pressure science came together from North America, Europe and Asia. The group discussed the most promising and important new physics experiments that will be enabled by the unique combination of high-power lasers with the world- class LCLS free-electron laser X-ray beam.

High-power laser facilities across the world can now reach petawatt (1015 W) laser power to drive laser targets into an extreme matter state. In this environment, the material at the laser focus is heated to high temperatures, which drive high- pressure high-density shocks, nuclear processes, as well as large magnetic and electric fields. These experiments hold great promise for laser-based acceleration of protons, electrons and ions to high energies, and for creating anti-matter and fusion neutrons. Furthermore, these processes produce secondary ultrafast X-ray and -ray emissions.

The LCLS X-ray beam will enable novel research projects that take advantage of its unique in situ probing capability to help understand the plasma and material physics within the primary laser target, and to optimize the production of laser- accelerated particles and radiation. In addition, the laser-produced radiation is itself of great interest for heating matter for a wide range of applications, including fusion and cancer research. LCLS will be able to measure these ultrafast interaction processes in secondary targets. A third class of experiments will combine LCLS with laser driven X-rays for performing X-ray pump/X-ray probe measurements with complementary spectra, thus helping to resolve the ultrafast evolution of the physical properties of matter.

In four oral presentation sessions, one poster and one discussion session, workshop attendees developed the most promising high-impact science projects for the Matter in Extreme Conditions (MEC) instrument at LCLS. There was particular emphasis on prioritizing new laser, diagnostic and target developments for MEC. In addition, new collaborations were established to best use MEC’s existing and future high-power laser capabilities.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 MEC User Workshop on High-Power Lasers FWP#: 100189

At present, the MEC instrument combines the LCLS X-ray beam with two nanosecond Joule-class lasers that can irradiate targets at intensities approaching 1014 W/cm2, which can launch strong shocks or ramp-compress solids to high pressures. Of particular interest for the workshop was MEC’s short-pulse laser, which will be upgraded twice during 2014: first to 25 TW (1J, 40 fs, 5 Hz) and then to 200 TW (8J, 40 fs, 0.002 Hz) peak power.

The workshop’s first oral presentation session was devoted to recent experimental results obtained at MEC during its first 12 months of operation. The speakers (H. J. Lee, A. Gleason, L. B. Fletcher, B. Nagler, G. Monaco, A. Ravasio and S. Vinko) presented highly successful new experimental studies. Generally, the experiments can be classified into four classes that have used LCLS x-ray probes to characterize extreme-matter states that were produced with the nanosecond beams or by LCLS itself. These include: 1) ultrafast diffraction measurements of phase transitions in materials of interest to fusion, earth and planetary sciences; 2) spectrally resolved x-ray Thomson scattering of Compton, plasmon and ion acoustic features; 3) absorption and fluorescence spectroscopy, and 4) phase-contrast imaging of shocks and ultrafast phenomena.

During these talks, the uniformity of the laser spots was brought up, because it can affect the interpretation of experiments that require large samples. Equivalent-plane cameras were suggested for future experiments to enable users to measure the laser-beam uniformity at the plane of the target and to determine the evolving laser beam’s phase changes from shot to shot. In addition, attendees recommended as desirable improvements increasing the total laser energy on target, laser pulse shaping and shot-by-shot pulse monitoring.

Raising these issues has had immediate impact. Shortly after the workshop, the LCLS laser engineering team demonstrated ramp-laser pulse shapes that were used successfully in material compression experiments. In addition, the team recently increased laser energy on target from 4.5J to 6 J in 3 ns long pulses.

The first workshop day concluded with an update on technologies for achieving high-power laser pulses for future high- field research and a poster session. The latter provided an opportunity for students and young researchers to present their work and ideas for novel experiments at LCLS.

The poster session further highlighted the importance of first using theory and simulations to explore the most interesting science questions computationally and then to field controlled experiments. The high-power laser-matter interaction regime is theoretically and computationally very challenging. Particle speeds approach the speed of light, so fluid-hybrid schemes often do not apply. Kinetic modeling, like a particle-in-cell (PIC) scheme, is often required.

An example of a successful simulation approach employs adaptive particle refinement strategies that allow researchers to perform full-scale 2D simulations of an experiment at the required resolution with about 1 million CPU-hours. This can be accomplished in an adaptive scheme by creating additional simulation particles and randomizing them during the simulation.

Opening the second day of the workshops were SLAC director C. C. Kao, DOE Fusion Energy Sciences program manager A. Satsangi, and LCLS interim director U. Bergmann. After his warm welcome, Kao described the competitive landscape and access opportunities that use LCLS for research. Satsangi pointed out potential future funding opportunities for academic work at MEC through Fusion Energy Science programs, High Energy Density Laboratory Plasma Joint Program and the NSF/DOE Partnership. Bergmann reviewed recent science opportunities at all six LCLS instruments. He pointed out that MEC received its highest number of new proposals for Run 9: 35 out of 195 total for LCLS. He expects a success rate of 20-25 percent. He also challenged the MEC community to evaluate a single-pulse kicker option for increased access to the LCLS beam through a shared-operation mode.

The second oral presentation session consisted of two parts, each discussing frontier research in high-intensity laser- matter interactions. The speakers of the first part (T. Ditmire, K. Krushelnik, B. M. Hegelich) pointed towards a bright future with opportunities for transformative discoveries by using LCLS as a new precision tool for controlling and optimizing the production of radiation sources with lasers incident on thin films at intensities of 1018-1021 W/cm2. This class of experiments will allow producing >100 MeV protons for possible cancer therapies or for isochoric heating studies of matter, such as testing the equation of state of dense matter. Other radiation sources can drive intense x-ray sources or energetic electrons and positrons. In the talks, the speakers showed new experimental results from the Texas PetaWatt and the Michigan Hercules lasers. These high-power lasers’ temporal and spatial beam quality has been key for

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 MEC User Workshop on High-Power Lasers FWP#: 100189 them becoming efficient and stable sources. It was also suggested that the MEC’s first laser upgrade include a plasma mirror to obtain a low pre-pulse level, which would be important for generating MeV proton beams.

The speakers of the second part (E. I. Moses, D. H. Froula, T. Tajima and M. Roth) focused on laser-produced radiation and particles. While Moses presented encouraging new progress towards achieving fusion conditions by inertial confinement fusion on the National Ignition Facility, the direct irradiation of matter by high-power laser-produced radiation sources has recently received wide attention for thermodynamic studies of heating, heat transport and ion stopping.

The third session described ongoing and future high-power laser developments that are particularly relevant for LCLS. In 2016, the Helmholtz International Beamline for Extreme Fields (HIBEF) instrument expects to commission a 200 TW, 10 Hz laser combined with an x-ray free electron laser beam for user experiments at XFEL at DESY in Germany. In addition, a kilojoule class laser is being planned for studying strong shocks. Another important thrust area is the European Light Infrastructure (ELI) project, where multiple sites support a range of attosecond, high-energy-density and laser-driven particle beams. Here, multiple PW laser beams at one site will allow pump-probe studies with laser- generated x-rays.

These projects particularly benefit from lasers that can deliver high peak power, high energy and high average power. Lawrence Livermore National Laboratory is currently developing lasers projected to deliver 30 J, 30 fs, 10 Hz, 130 kW. Other high-average-power laser projects for x-ray free electron lasers are being pursued at the Rutherford Appleton Laboratory in the UK, and at the Helmholtz Zentrum Dresden-Rossendorf in Germany.

At the workshop’s final oral presentation session (P. Chen, J. Wark) discussed new directions in high-energy-density physics enabled by combining high-power lasers and free electron laser sources. The speakers showed a detailed study of phase transitions in solids at high pressure and explored new experiments to measure quantum electron dynamics effects, where lasers allow studies with a strong accelerating force.

The workshop concluded with a discussion session. The speakers and discussion leaders (W. Goldstein, P. Heimann, A. Thomas, M. Wei, R. P. Drake, S. Hau-Riege, P. Norris, W. White) touched many areas, such as prospects for students and young researchers, access to the MEC lasers, and hardware needs to perform cutting edge research at MEC.

Goldstein presented recent work performed by successful young researchers in the field of high-energy-density science and explained the importance to continue providing opportunities in this area. Heimann followed this presentation briefly reviewing the MEC schedule and capabilities and describing access to MEC lasers. He announced a call for laser-only experiments at MEC aimed at demonstrating capabilities that may subsequently be applied in experiments combined with the LCLS X-ray beam. Shortly after the workshop, this call was announced on the LCLS website, and all workshop participants were notified.

The speakers then summarized input that they had received during the time leading up to the workshop, particularly concerning the areas of diagnostics, targets, and optics. During the ensuing discussion, several participants reiterated the importance of improving the drive lasers. In addition, with the imminent upgrade of the short-pulse laser capability, it will be important to have new diagnostics for characterizing the laser and measuring the laser-produced radiation and energetic particles. Many of these experiments require unique high-precision laser targets. Moreover, MEC can perform 100 shots per day requiring a total of 500 targets per 5-day experimental run. Thus, a reliable source of targets will be very important to the success of MEC laser experiments.

The competitive landscape around LCLS and MEC makes it imperative that experiments are well planned and supported by theoretical modeling and simulations. For this purpose, software packages available from universities, national laboratories and companies need to be made available to users. In addition, future users may find view-factor software that calculates alignment and diagnostic camera outputs specific for each experiment on MEC to be very helpful.

The last part of the discussion session was devoted to ideas for future lasers at LCLS. These include further upgrades of laser power, high repetition rate soft x-ray lasers (10 mJ, 10s of nm, 100 Hz), and laser Spike Trains of Uneven Duration and Delay (STUD). Particularly interesting are high-power lasers approaching and exceeding PW power. The participants preferred PW lasers that would deliver 100 J or more laser energy on target.

Field Work Proposal – SLAC National Accelerator Laboratory Date Submitted: 6/23/2014 MEC User Workshop on High-Power Lasers FWP#: 100189

The workshop concluded with the recommendation to hold regular discussion sessions at conferences and meetings to provide the user community with continued input to MEC and LCLS.

Company sponsors (General Atomics, Amplitude Technologies Coherent, Continuum, GT Advanced Technologies, Imagine Optic, LEO, National Energetics, Northrop Grumman, PRISM Computational Sciences and THALES), and institutes from Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, Stanford and SLAC National Accelerator Laboratory also supported the workshop.

More information can be found on the conference website: http://conf-slac.stanford.edu/hpl-2013/

Expected Progress in FY2015

Dr. Glenzer, co-PIs, sponsors and staff at SLAC are currently in the planning stages for a second workshop to be held October 7-8, 2014.

Expected Progress in FY2016 Dr. Glenzer, co-PIs, sponsors and staff anticipate convening a third workshop to be held in 2016.

Publications for FY13 & FY14 (Oct 1st 2012 to date) 1. User Workshop on High-Power Lasers at the Linac Coherent Light Source, by R. Falcone, S. H. Glenzer, and S. Hau-Riege, Synchrotron Radiation News, Vol. 27, No. 2, 56 (2014). http://www.tandfonline.com/doi/full/10.1080/.U39-ul6prwI