DOCSLIB.ORG

Topological Constraints and Defects in Spin Ice Ludovic D.C

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Topological Constraints and Defects in Spin Ice Ludovic D.C Topological Constraints and Defects in Spin Ice Ludovic D.C. Jaubert To cite this version: Ludovic D.C. Jaubert. Topological Constraints and Defects in Spin Ice. Condensed Matter [cond-mat]. Ecole normale supérieure de lyon - ENS LYON, 2009. English. tel-00462970 HAL Id: tel-00462970 https://tel.archives-ouvertes.fr/tel-00462970 Submitted on 10 Mar 2010 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Distributed under a Creative Commons Attribution| 4.0 International License N◦ d’ordre : 528 N◦ attribu´epar la biblioth`eque : ENSL528 Th`ese en vue d’obtenir le grade de Docteur de l’Universit´ede Lyon - Ecole Normale Sup´erieure de Lyon Laboratoire de Physique, ENS Lyon Ecole Doctorale de Physique et d’Astrophysique de Lyon pr´esent´ee et soutenue publiquement le 23 / IX / 2009 par Ludovic D. C . Jaubert Topological Constraints and Defects in Spin Ice r´ealis´ee sous la direction de Peter C . W . Holdsworth Devant la commission d’examen form´ee de : M. Fabien Alet Membre/Rapporteur M. Leon Balents Membre M. Benjamin Canals Membre/Rapporteur M. Peter Holdsworth Directeur de th`ese M. Philippe Mendels Pr´esident M. Fr´ed´eric Mila Membre i Table of Contents Acknowledgements 1 I Introduction 5 I.1 MagneticMaterials ............................... 5 I.1.a Origin of magnetism in condensed matter . ... 6 I.1.b Phasetransitions ............................ 11 I.1.c 2-dimensional XY -model........................ 15 I.2 FrustrationinPhysics ............................ 18 I.2.a Randomness............................... 19 I.2.b Geometricalfrustration. 19 I.3 SpinIce ..................................... 23 I.3.a Origin .................................. 23 I.3.b DipolarInteractions . .. .. 28 I.3.c Magnetic Monopoles in Spin ice . 33 I.3.d Magneticfield.............................. 39 I.3.e Dynamics ................................ 46 I.3.f Spinicecandidates ........................... 48 I.4 Plan ....................................... 49 II Methods 51 II.1 Presentationofthemodel . .. 51 II.2 MonteCarlo................................... 53 II.3 Wormalgorithm................................. 57 II.4 EwaldMethod.................................. 62 II.4.a Generalpresentation . 62 II.4.b Analytical calculation of the series . ..... 64 II.4.c Numerical application to spin ice . ... 67 II.5 Transfermatrix ................................. 69 II.5.a One dimensional Ising model . 69 II.5.b 6-vertexmodel ............................. 71 II.6 Husimitree ................................... 74 II.6.a Betheapproximation . 74 II.6.b Bethelattice............................... 75 II.6.c Husimitree ............................... 77 ii TABLE OF CONTENTS II.6.d Recursion on the Husimi tree for spin ice . .... 78 III Topological phase transitions 81 III.1ConstrainedManifold. ... 81 III.1.a Natureofthetransitions . .. 81 III.1.b Topologicalconstraints . ... 84 III.2 Kasteleyn transition: δ =0........................... 88 III.2.aHusimiTree ............................... 89 III.2.bWormalgorithm ............................ 92 III.2.c Upper-critical dimension . ... 94 III.2.dWorldlinesforbosons . 95 III.2.e Experiments............................... 96 III.3 A tuneable Kasteleyn transition: h> 0, δ> 0................ 98 III.4 KDP transition: h =0 .............................101 III.4.a Apparent 1st ordertransition . .101 III.4.b Multicritical Point of -order.....................106 ∞ III.4.c Rigourous proof: Transfer Matrix method . .114 III.4.d Mapping onto a quantum phase transition . .122 III.4.e Correlations ...............................125 III.4.f Experiments...............................126 IV Constrained Monopoles Dynamics 133 IV.1Presentationoftheproblem . 133 IV.1.a Magneticmonopoles . .133 IV.1.bDynamicsinspinice . .136 IV.2 Deconfined quasi-particles . .137 IV.2.a Quantumtunnelling . .138 IV.2.b Arrheniusargument . .139 IV.3Spinfreezing................................... 142 IV.3.a Dipolarspinice .............................142 IV.3.b Magnetic monopoles and Dirac strings . 143 IV.3.c Comparisontoexperiments . 148 IV.4Monopolesinafield ..............................153 V Zero Field Susceptibility in Ho2Ti2O7 155 V.1 An appealing experimental result . .155 V.2 Husimitree ...................................156 V.3 Q-dependance of the susceptibility . 160 VI Conclusion 165 A Generalisation of Pauling’s argument 169 TABLE OF CONTENTS iii B Demagnetisation Effect 171 C Neutron Scattering & Pinch Points 173 iv List of Figures I.1 Hydrogenmolecule .............................. 8 I.2 GibbsenergyforLandautheory. 13 I.3 Signature of phase transitions in the susceptibility . ........... 16 I.4 ExcitationsoutoftheXYgroundstate. ... 17 I.5 Frustration .................................. 18 I.6 Frustratedlattices .............................. 20 I.7 Signature of frustration in the susceptibility . ......... 21 I.8 Pyrochlorelattice............................... 24 I.9 Models equivalent to spin ice . 26 I.10 Degeneracyinspinice ............................ 27 I.11 Zero-point entropy in Dy2Ti2O7 ....................... 29 I.12 Hyperfine coupling in Ho2Ti2O7 ....................... 30 I.13 Scattering function in spin ice . .... 31 I.14 Phase transition in dipolar spin ice . ..... 33 I.15 Ground state of the dipolar spin ice model . ..... 34 I.16 Coulombpotential .............................. 38 I.17 Dumbbellmodel ............................... 38 I.18 Groundstateina110field. .. .. 41 I.19 Phase diagram of dipolar spin ice in a 110 field . ..... 42 I.20 GroundstateofKagomeIce . 43 I.21 Phase Diagram and Kagome Ice plateau in a 111 field . ..... 44 I.22 Decoupled spin in a 112-tilted field . .... 45 I.23 Spinicedynamics............................... 46 II.1 Presentationofthemodel . 52 II.2 Degeneracy lift of the 2 in - 2 out tetrahedra in a 001 magnetic field . 52 II.3 Degeneracy lift of the 2 in - 2 out tetrahedra with bond distortion. 53 II.4 LoopsfromtheWormalgorithm . 58 II.5 Mapping from a spin configuration to an ensemble of strings ....... 59 II.6 IllustrationoftheEwaldsum . .. 63 II.7 Periodic boundary conditions in the Ewald method . ....... 69 II.8 Isingchain................................... 70 II.9 6-vertexmodel ................................ 72 II.10 Configurationsofthe6-vertexmodel . ..... 73 LIST OF FIGURES v II.11 Betheapproximation . 75 II.12 Bethelattice ................................. 76 II.13 Husimitree .................................. 78 III.1 Constructionofastring . .. 83 III.2 Gibbspotential ................................ 85 III.3 Smallclosedloop ............................... 86 III.4 Kasteleyn transition for biomembranes . ....... 89 III.5 3d Kasteleyntransitioninspinice. 92 III.6 Finitesizeeffects .............................. 94 III.7 Logarithmic corrections at the upper-critical dimension.......... 95 III.8 Correlationsina001field . .. 96 III.9 Magnetisation in a 001 field for Dy2Ti2O7 and Ho2Ti2O7 ......... 98 III.10 Tuneable Kasteleyn transition . ...... 99 III.11 Logarithmic corrections at the upper-critical dimension . .100 III.12 Entropyontheconstrainedmanifold . ......105 III.13 KDPtransitionwithdefects . .106 III.14 Gibbs energy for Landau theory (multi-critical point)...........107 III.15 Equiprobability of the sectors . ......112 III.16 Energy E vs magnetisation M ........................113 III.17 Probability distribution of the energy . .........114 III.18 Densityoftetrahedra. 115 III.19 3d TransferMatrix ..............................116 III.20 2d projectionofthepyrochlorelattice. 118 III.21 MeanFieldcriticalcorrelations . .......126 III.22 Anisotropiccorrelations . .127 III.23 Finite size effects in the correlation . ........128 III.24 Uniaxialpressure . .. .. .. 130 III.25 Dy2Ti2O7 underuniaxialpressure . 131 IV.1 Coulombpotential ..............................135 IV.2 Emergenceofmonopoles . 136 IV.3 Experimentalrelaxationtime . 137 IV.4 Deconfinedmonopoles ............................140 IV.5 Densityofmonopoles............................. 144 IV.6 Creation/annihilation of a pair of quasi-particles . ............146 IV.7 Spin freezing in Dy2Ti2O7 ..........................150 IV.8 Influence of a magnetic field on the dynamics . .151 IV.9 Influence of dilution on the dynamics . .152 IV.10 Transientmonopolecurrent: . .154 IV.11 Monopoledensityprofile . 154 V.1 Experimental susceptibility . 156 V.2 Susceptibility crossover . 159 V.3 Scatteringfunction .............................. 162 vi LIST OF FIGURES V.4 Susceptibility χ(q,T ).............................163 vii List of Tables I.1 Groundstateelectronicconfiguration . ..... 25 I.2 Crystalfieldlevel............................... 25 I.3 Nearest neighbour interactions . .... 32 II.1 ProbabilitiesoftheWormalgorithm . .... 61 IV.1 Mapping from the dipolar spin ice to the dumbbell model . .......133 IV.2 Energy scales resulting from a single spin flip . .......141 Acknowledgements Ces trois derni`eres ann´ees ayant ´et´eassez pleines (voire intenses), cela risque de me pren- dre pas mal de temps pour remercier ou saluer tout ceux qui m’ont aid´eou que j’ai rencontr´eau fil de ma
Load more

Recommended publications
  • Investigation of the Magnetic and Magnetocaloric Properties of Complex Lanthanide Oxides
    Investigation of the magnetic and magnetocaloric properties of complex lanthanide oxides Paromita Mukherjee Department of Physics University of Cambridge This dissertation is submitted for the degree of Doctor of Philosophy King’s College April 2018 This thesis is dedicated to my parents. Declaration I hereby declare that except where specific reference is made to the work of others, the contents of this dissertation are original and have not been submitted in whole or in part for consideration for any other degree or qualification in the University of Cambridge, or any other university. This dissertation is my own work and contains nothing which is the outcome of work done in collaboration, except as specified in the text and Acknowledgements. This dissertation contains fewer than 60,000 words including abstract, tables, footnotes and appendices. Some of the work described herein has been published as follows: Chapter 3 is an expanded version of: P. Mukherjee, A. C. Sackville Hamilton, H. F. J. Glass, S. E. Dutton, Sensitivity of magnetic properties to chemical pressure in lanthanide garnets Ln3A2X3O12, Ln = Gd, Tb, Dy, Ho, A = Ga, Sc, In, Te, X = Ga, Al, Li, Journal of Physics: Condensed Matter 29, 405808 (2017). Chapter 4 contains material from: P. Mukherjee, S. E. Dutton, Enhanced magnetocaloric effect from Cr substitution in Ising lanthanide gallium garnets Ln3CrGa4O12 (Ln = Tb, Dy, Ho), Advanced Functional Materials 27, 1701950 (2017). P. Mukherjee, H. F. J. Glass, E. Suard, and S. E. Dutton, Relieving the frustration through Mn3+ substitution in holmium gallium garnet, Physical Review B 96, 140412(R) (2017). Chapter 5 contains material from: P.
    [Show full text]
  • A Highly Scalable Dynamical Matrix Approach Applied to a Fibonacci- Distorted Artificial Spin Ice
    University of Kentucky UKnowledge Physics and Astronomy Faculty Publications Physics and Astronomy 3-8-2021 Magnetic Normal Mode Calculations in Big Systems: A Highly Scalable Dynamical Matrix Approach Applied to a Fibonacci- Distorted Artificial Spin Ice Loris Giovannini Università di Ferrara, Italy Barry W. Farmer University of Kentucky, [email protected] Justin S. Woods University of Kentucky, [email protected] Ali Frotanpour University of Kentucky, [email protected] Lance E. De Long University of Kentucky, [email protected] Follow this and additional works at: https://uknowledge.uky.edu/physastron_facpub See next page for additional authors Part of the Physics Commons Right click to open a feedback form in a new tab to let us know how this document benefits ou.y Repository Citation Giovannini, Loris; Farmer, Barry W.; Woods, Justin S.; Frotanpour, Ali; De Long, Lance E.; and Montoncello, Federico, "Magnetic Normal Mode Calculations in Big Systems: A Highly Scalable Dynamical Matrix Approach Applied to a Fibonacci-Distorted Artificial Spin Ice" (2021). Physics and Astronomy Faculty Publications. 673. https://uknowledge.uky.edu/physastron_facpub/673 This Article is brought to you for free and open access by the Physics and Astronomy at UKnowledge. It has been accepted for inclusion in Physics and Astronomy Faculty Publications by an authorized administrator of UKnowledge. For more information, please contact [email protected]. Magnetic Normal Mode Calculations in Big Systems: A Highly Scalable Dynamical Matrix Approach Applied to a Fibonacci-Distorted Artificial Spin Ice Digital Object Identifier (DOI) https://doi.org/10.3390/magnetochemistry7030034 Notes/Citation Information Published in Magnetochemistry, v.
    [Show full text]
  • Emergence of Nontrivial Spin Textures in Frustrated Van Der Waals Ferromagnets
    nanomaterials Article Emergence of Nontrivial Spin Textures in Frustrated Van Der Waals Ferromagnets Aniekan Magnus Ukpong Theoretical and Computational Condensed Matter and Materials Physics Group, School of Chemistry and Physics, University of KwaZulu-Natal, Pietermaritzburg 3201, South Africa; [email protected]; Tel.: +27-33-260-5875 Abstract: In this work, first principles ground state calculations are combined with the dynamic evolution of a classical spin Hamiltonian to study the metamagnetic transitions associated with the field dependence of magnetic properties in frustrated van der Waals ferromagnets. Dynamically stabilized spin textures are obtained relative to the direction of spin quantization as stochastic solutions of the Landau–Lifshitz–Gilbert–Slonczewski equation under the flow of the spin current. By explicitly considering the spin signatures that arise from geometrical frustrations at interfaces, we may observe the emergence of a magnetic skyrmion spin texture and characterize the formation under competing internal fields. The analysis of coercivity and magnetic hysteresis reveals a dynamic switch from a soft to hard magnetic configuration when considering the spin Hall effect on the skyrmion. It is found that heavy metals in capped multilayer heterostructure stacks host field-tunable spiral skyrmions that could serve as unique channels for carrier transport. The results are discussed to show the possibility of using dynamically switchable magnetic bits to read and write data without the need for a spin transfer torque. These results offer insight to the spin transport signatures that Citation: Ukpong, A.M. Emergence dynamically arise from metamagnetic transitions in spintronic devices. of Nontrivial Spin Textures in Frustrated Van Der Waals Keywords: spin current; van der Waals ferromagnets; magnetic skyrmion; spin Hall effect Ferromagnets.
    [Show full text]
  • Quantum Spin-Ice and Dimer Models with Rydberg Atoms
    PHYSICAL REVIEW X 4, 041037 (2014) Quantum Spin-Ice and Dimer Models with Rydberg Atoms A. W. Glaetzle,1,2,* M. Dalmonte,1,2 R. Nath,1,2,3 I. Rousochatzakis,4 R. Moessner,4 and P. Zoller1,2 1Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria 2Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck, Austria 3Indian Institute of Science Education and Research, Pune 411 008, India 4Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany (Received 21 April 2014; revised manuscript received 27 August 2014; published 25 November 2014) Quantum spin-ice represents a paradigmatic example of how the physics of frustrated magnets is related to gauge theories. In the present work, we address the problem of approximately realizing quantum spin ice in two dimensions with cold atoms in optical lattices. The relevant interactions are obtained by weakly laser-admixing Rydberg states to the atomic ground-states, exploiting the strong angular dependence of van der Waals interactions between Rydberg p states together with the possibility of designing steplike potentials. This allows us to implement Abelian gauge theories in a series of geometries, which could be demonstrated within state-of-the-art atomic Rydberg experiments. We numerically analyze the family of resulting microscopic Hamiltonians and find that they exhibit both classical and quantum order by disorder, the latter yielding a quantum plaquette valence bond solid. We also present strategies to implement Abelian gauge theories using both s- and p-Rydberg states in exotic geometries, e.g., on a 4–8 lattice.
    [Show full text]
  • Spectroscopy of Spinons in Coulomb Quantum Spin Liquids
    MIT-CTP-5122 Spectroscopy of spinons in Coulomb quantum spin liquids Siddhardh C. Morampudi,1 Frank Wilczek,2, 3, 4, 5, 6 and Chris R. Laumann1 1Department of Physics, Boston University, Boston, MA 02215, USA 2Center for Theoretical Physics, MIT, Cambridge MA 02139, USA 3T. D. Lee Institute, Shanghai, China 4Wilczek Quantum Center, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China 5Department of Physics, Stockholm University, Stockholm Sweden 6Department of Physics and Origins Project, Arizona State University, Tempe AZ 25287 USA We calculate the effect of the emergent photon on threshold production of spinons in U(1) Coulomb spin liquids such as quantum spin ice. The emergent Coulomb interaction modifies the threshold production cross- section dramatically, changing the weak turn-on expected from the density of states to an abrupt onset reflecting the basic coupling parameters. The slow photon typical in existing lattice models and materials suppresses the intensity at finite momentum and allows profuse Cerenkov radiation beyond a critical momentum. These features are broadly consistent with recent numerical and experimental results. Quantum spin liquids are low temperature phases of mag- The most dramatic consequence of the Coulomb interaction netic materials in which quantum fluctuations prevent the between the spinons is a universal non-perturbative enhance- establishment of long-range magnetic order. Theoretically, ment of the threshold cross section for spinon pair production these phases support exotic fractionalized spin excitations at small momentum q. In this regime, the dynamic structure (spinons) and emergent gauge fields [1–4]. One of the most factor in the spin-flip sector observed in neutron scattering ex- promising candidate class of these phases are U(1) Coulomb hibits a step discontinuity, quantum spin liquids such as quantum spin ice - these are ex- 1 q 2 q2 pected to realize an emergent quantum electrodynamics [5– S(q;!) ∼ S0 1 − θ(! − 2∆ − ) (1) 11].
    [Show full text]
  • Magnetic Monopoles in Spin Ice
    Master of Science Thesis Magnetic Monopoles in Spin Ice Axel Nordstr¨om Supervisor: Patrik Henelius Department of Theoretical Physics, School of Engineering Sciences Royal Institute of Technology, SE-106 91 Stockholm, Sweden Stockholm, Sweden 2014 Typeset in LATEX Examensarbete inom ¨amnet teoretisk fysik f¨or avl¨aggande av civilingenj¨orsexamen inom utbildningstprogrammet Teknisk fysik. Graduation thesis on the subject Theoretical Physics for the degree of Master of Science in Engineering from the School of Engineering Sciences. TRITA-FYS 2014:26 ISSN 0280-316X ISRN KTH/FYS/{14:26{SE © Axel Nordstr¨om,May 2014 Printed in Sweden by Universitetsservice US AB, Stockholm May 2014 Abstract In this thesis, we investigate the behaviour of magnetic monopoles in spin ice when an external magnetic field is applied. We find that steady state direct currents of magnetic monopoles cannot be maintained for long and consider the possibility of alternating magnetic currents by investigating the alternating current susceptibility using both analytical and Monte Carlo techniques. Moreover, we look at the transition that occurs when a magnetic field is ap- plied in a 111 direction. We show that the transition is a continuous crossover rather thanh a phasei transition in the nearest neighbour model and we study the behaviour of the system during the crossover, especially at the critical field where a temperature independent state appears. Using Monte Carlo methods and analyti- cal methods based on the Bethe approximation, we find that the mean monopole density is 0.4 monopoles per tetrahedron in the temperature independent state at the critical field. Keywords: spin ice, magnetic monopoles, phase transitions.
    [Show full text]
  • Emergent Phenomena in Spin Crossover Systems
    Emergent Phenomena in Spin Crossover Systems Jace Alex Cruddas B.Sc. (Hons) Candidate’s ORCID A thesis submitted for the degree of Doctor of Philosophy at The University of Queensland in Year School of Mathematics and Physics Abstract In general, a spin crossover (SCO) system is any complex, material or framework containing two thermodynamically accessible spin-states: one high-spin (HS) and one low-spin (LS). The transition between spin-states is addressable by temperature, pressure, light irradiation, electric and magnetic fields, and chemical environment. The transition itself can be first-order, exhibiting hysteresis, continuous or a crossover. Typically, accompanied by the ferroelastic ordering of spin-states. It can also be part of an incomplete or multi-step transition accompanied by the antiferroelastic ordering of spin-states. In general, any alterations to the structural characteristics of SCO systems can have an effect on their bulk properties and behaviours. Consequently, constructing structure-property relations has traditionally been an extremely challenging task, and one of both great theoretical and experimental interest. Understanding the mechanisms behind these bulk properties and behaviours could lead to the rational design of SCO systems with enhanced applications and the synthesis of novel properties and behaviours. In this thesis we show that a simple, elastic model of SCO systems hosts almost all experimentally reported SCO properties and behaviours. We demonstrate clear structure-property relations that explain these results, derive the mechanisms of multi-step transitions and explain why and how intermolecular interactions play a role. We also propose that a new exotic state of matter could exist in elastically frustrated SCO materials and frameworks.
    [Show full text]
  • Neutron Scattering Studies of Spin Ices and Spin Liquids
    Collection SFN 13, 04001 (2014) DOI: 10.1051/sfn/20141304001 C Owned by the authors, published by EDP Sciences, 2014 Neutron scattering studies of spin ices and spin liquids T. Fennell Laboratory for Neutron Scattering, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland Abstract. In frustrated magnets, competition between interactions, usually due to incompatible lattice and exchange geometries, produces an extensively degenerate manifold of groundstates. Exploration of these states results in a highly correlated and strongly fluctuating cooperative paramagnet, a broad classification which includes phases such as spin liquids and spin ices. Generally, there is no long range order and associated broken symmetry, so quantities typically measured by neutron scattering such as magnetic Bragg peaks and magnon dispersions are absent. Instead, spin correlations characterized by emergent gauge structure and exotic fractional quasiparticles may emerge. Neutron scattering is still an excellent tool for the investigation these phenomena, and this review outlines examples of frustrated magnets on the pyrochlore and kagome lattices with reference to experiments and quantities of interest for neutron scattering. 1. PREAMBLE In physics, a frustrated system is one in which all interactions cannot be simultaneously minimized, which is also to say that there is competition amongst the interactions. Frustration is most commonly associated with spin systems [1], where its consequences can be particularly well identified, but is by no means limited to magnetism. Frustrated interactions are also relevant in certain structural problems [2–6], colloids and liquid crystals [7], spin glasses [8], stripe phases [9, 10], Josephson junction arrays [11], stellar nuclear matter [12, 13], social dynamics [14], origami [15], and protein folding [16], to name a few.
    [Show full text]
  • Spin Ice in a Field: Quasi-Phases and Pseudo-Transitions
    Spin ice in a field: quasi-phases and pseudo-transitions. P.N. Timonin Southern Federal University, Rostov-on-Don, 344090, Russia. Thermodynamics of the short-range model of spin ice magnets in a field is considered in the Bethe – Peierls approximation. The results obtained for [111], [100] and [011] fields agrees reasonably well with the existing Monte-Carlo simulations and some experiments. Quite remarkably all extremely sharp field-induced anomalies are described in this approximation by the analytical functions of temperature and applied field. In spite of the absence of true phase transitions the analysis of the entropy and specific heat reliefs over H-T plane allows in most cases to discern the “pseudo-phases” with specific character of spin fluctuations and outline the curves of more or less sharp “pseudo-transitions” between them. The discovery of spin ice compounds [1, 2] has opened a wide perspective in the studies of real geometrically frustrated magnets with their reach physics stemming from the macroscopically degenerate ground states. The more so as they can be described by the relatively simple Ising model with the nearest-neighbour exchange on the pyrochlore lattice. This is due to the lucky chance that strong dipole interactions in these compounds have a negligible effect on the low-energy excitations of the Ising moments directed along the lines connecting the centres of corner-sharing tetrahedra [3]. So low-temperature physics of spin-ices can be adequately captured by the short-range Ising model except for the ultra low temperatures where the equilibrium properties may be unobservable [4]. Such model predicts the absence of phase transitions in zero field in accordance with experiments in the (established) acknowledged spin ice compounds [1, 2].
    [Show full text]
  • Publication List (May 2020) Armin Kleibert Publications in Refereed
    Publication List (May 2020) Armin Kleibert Publications in Refereed Scientific Journals 87. K. Hofhuis, A. Hrabec, H. Arava, N. Leo, Y.-L. Huang, R. V. Chopdekar, S. Parchenko, A. Kleibert, S. Koraltan, C. Abert, C. Vogler, D. Suess, P. M. Derlet, and L. J. Heyderman Thermally Superactive Artificial Kagome Spin Ice Structures Obtained with the Interfacial Dzyaloshinskii-Moriya Interaction Submitted (2020) 86. A. Ciuciulkaite, K. Mishra, M. V. Moro, I.-A. Chioar, R. Rowan Robinson, S. Parchenko, A. Kleibert, B. Lindgren, G. Andersson, C. Davies, A. Kimel, A. Kirilyuk, and V. Kapaklis Design of Amorphous TbxCo100-x Alloys for All-Optical Magnetization Switching Submitted (2020), arxiv.org/abs/2002.07544 85. H. Arava, E. Y. Vedmedenko, J. Cui, J. Vijayakumar, A. Kleibert, and L. J. Heyderman Control of Emergent Magnetic Monopole Currents in Artificial Spin Ice Submitted (2020) 84. B. Rösner, S. Finizio, F. Koch, F. Döring, V. A. Guzenko, M. Langer, E. Kirk, B. Watts, M. Meyer, J. Loroña Ornelas, A. Späth, S. Stanescu, S. Swaraj, R. Belkhou, T. Ishikawa, T. F. Keller, B. Gross, M. Poggio, R. H. Fink, J. Raabe, A. Kleibert, and C. David Soft X-Ray Microscopy with Single-Digit Nanometer Resolution Submitted (2020) 83. M. Saccone, K. Hofhuis, D. Bracher, A. Kleibert, S. van Dijken, and A. Farhan Elevated Effective Dimension in Tree-Like Nanomagnetic Cayley Structures Nanoscale 12, 189 (2020), DOI:10.1039/c9nr07510k 82. M. Wyss, S. Gliga, D. Vasyukov, L. Ceccarelli, G. Romagnoli, J. Cui, A. Kleibert, R. L. Stamps, and M. Poggio Stray-Field Imaging of a Chiral Artificial Spin Ice During Magnetization Reversal ACS Nano 13, 13910 (2019), DOI:10.1021/acsnano.9b05428 81.
    [Show full text]
  • Magnetic Monopoles in Spin Ice Physics of Bulk Spin Ice Materials
    Magnetricity and Monopoles Displacement vectors in water Magnetic Monopoles in Spin Ice Potential magnetic monopole capacitor? ice Spin vectors in Spin Ice (Bramwell & Harris 1997) • Spin ice materials like Ho2Ti2O7 are simple Artificial System: Nanomagnets atomic spins transparent crystals that include atoms of •Magnetic charge Q at each vertex in honeycomb “rare earth” elements arranged in corner- •Q=3 monopole defects linked tetrahedra. The atomic magnetic moments or “spins” point into or out of Q= +1 or Q= -1 Ice the tetrahedral (arrows). H2O - + • Magnetic monopoles - the magnetic - + + version of a charged particle like electrons - Spin flips make magnetic or protons – have recently been shown to monopoles analogous to water exist in spin ice. We have shown that ice’s ionic defects monopoles form a magnetic version of Q= +3 or Q= -3 electricity, or “magnetricity” at very low T. + - + - - + 2H2O = [H3O +OH ] = H3O +OH • We have fabricated arrays of nanomagnets in a spin ice geometry, to + - create magnetic monopole defects at room temperature Physics of Bulk Spin Ice Materials Monopoles in Artificial Spin Ice Nanostructures H •The spin ice state has been confirmed by neutron •Scanning electron scattering to be a vacuum for magnetic charge. SEM (a) (d) micrograph of the cobalt •Magnetic monopoles live in this vacuum. They honeycomb nanostructure.Q=+3 on are analogous to water’s ionic defects. Q=+1 site •Magnetic force micrograph H =-52.4 mT •Different spin ice materials have different Hx=-48.8mT x showing a negativelyQ=+1 on (b) (e) monopole concentrations. High pressure has been charged magnetic monopoleQ=-1 site used to create a new spin ice, Dy2Ge2O7 with the defect (bright yellow).
    [Show full text]
  • Magnetic Monopole Dynamics in Spin Ice L D C Jaubert, P C W Holdsworth
    Magnetic monopole dynamics in spin ice L D C Jaubert, P C W Holdsworth To cite this version: L D C Jaubert, P C W Holdsworth. Magnetic monopole dynamics in spin ice. Journal of Physics: Condensed Matter, IOP Publishing, 2011, 23, pp.164222. 10.1088/0953-8984/23/16/164222. hal- 01541666 HAL Id: hal-01541666 https://hal.archives-ouvertes.fr/hal-01541666 Submitted on 19 Jun 2017 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Distributed under a Creative Commons Attribution| 4.0 International License Magnetic Monopole Dynamics in Spin Ice L. D. C. Jaubert∗ and P. C. W. Holdsworth† October 6, 2010 ∗Max-Plack-Institut f¨ur Physik komplexer Systeme, 01187 Dresden, Germany. †Universit´ede Lyon, Laboratoire de Physique, Ecole´ Normale Sup´erieure de Lyon, 46 All´ee d’Italie, 69364 Lyon cedex 07, France. October 6, 2010 Abstract One of the most remarkable examples of emergent quasi-particles, is that of the ”fractionalization” of magnetic dipoles in the low energy configurations of materials known as ”spin ice”, into free and unconfined magnetic monopoles interacting via Coulomb’s 1/r law [Castelnovo et.
    [Show full text]