51
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Raman spectroscopic signature of fractionalized excitations in the harmonic-honeycomb iridates β- and γ-Li2IrO3. Nat Commun 2016; 7:12286. [PMID: 27457278 PMCID: PMC4963532 DOI: 10.1038/ncomms12286] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 06/20/2016] [Indexed: 11/25/2022] Open
Abstract
The fractionalization of elementary excitations in quantum spin systems is a central theme in current condensed matter physics. The Kitaev honeycomb spin model provides a prominent example of exotic fractionalized quasiparticles, composed of itinerant Majorana fermions and gapped gauge fluxes. However, identification of the Majorana fermions in a three-dimensional honeycomb lattice remains elusive. Here we report spectroscopic signatures of fractional excitations in the harmonic-honeycomb iridates β- and γ-Li2IrO3. Using polarization-resolved Raman spectroscopy, we find that the dynamical Raman response of β- and γ-Li2IrO3 features a broad scattering continuum with distinct polarization and composition dependence. The temperature dependence of the Raman spectral weight is dominated by the thermal damping of fermionic excitations. These results suggest the emergence of Majorana fermions from spin fractionalization in a three-dimensional Kitaev–Heisenberg system. Fractional excitations in quantum spin systems lead to exotic particles predicted in theory but difficult to observe in experiments. Here, Glamazda et al. report the dynamical Raman response of β- and γ-Li2IrO3 is dominated by thermal damping of fermionic excitations, suggesting the emergence of Majorana fermions from spin fractionalization.
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52
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Pedersen KS, Bendix J, Tressaud A, Durand E, Weihe H, Salman Z, Morsing TJ, Woodruff DN, Lan Y, Wernsdorfer W, Mathonière C, Piligkos S, Klokishner SI, Ostrovsky S, Ollefs K, Wilhelm F, Rogalev A, Clérac R. Iridates from the molecular side. Nat Commun 2016; 7:12195. [PMID: 27435800 PMCID: PMC4961767 DOI: 10.1038/ncomms12195] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 06/07/2016] [Indexed: 11/09/2022] Open
Abstract
New exotic phenomena have recently been discovered in oxides of paramagnetic Ir4+ ions, widely known as ‘iridates'. Their remarkable properties originate from concerted effects of the crystal field, magnetic interactions and strong spin-orbit coupling, characteristic of 5d metal ions. Despite numerous experimental reports, the electronic structure of these materials is still challenging to elucidate, and not attainable in the isolated, but chemically inaccessible, [IrO6]8– species (the simplest molecular analogue of the elementary {IrO6}8− fragment present in all iridates). Here, we introduce an alternative approach to circumvent this problem by substituting the oxide ions in [IrO6]8− by isoelectronic fluorides to form the fluorido-iridate: [IrF6]2−. This molecular species has the same electronic ground state as the {IrO6}8− fragment, and thus emerges as an ideal model for iridates. These results may open perspectives for using fluorido-iridates as building-blocks for electronic and magnetic quantum materials synthesized by soft chemistry routes. Iridates are known to exhibit a range of exotic electronic and magnetic behaviours but it is difficult to prepare isolated [IrO6]8− species via soft chemical routes. Here, the authors isolate the isoelectronic [IrF6]2− complex, and assess it as a model and for iridate analogues.
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Affiliation(s)
- Kasper S Pedersen
- CNRS, ICMCB, UPR 9048, Pessac 33600, France.,Univ. Bordeaux, CRPP, UPR 8641, Pessac 33600, France.,CNRS, ICMCB, UPR 9048, Pessac 33600, France.,Univ. Bordeaux, ICMCB, UPR 9048, Pessac 33600, France
| | - Jesper Bendix
- Department of Chemistry, University of Copenhagen, Copenhagen DK-2100, Denmark
| | - Alain Tressaud
- CNRS, ICMCB, UPR 9048, Pessac 33600, France.,Univ. Bordeaux, ICMCB, UPR 9048, Pessac 33600, France
| | - Etienne Durand
- CNRS, ICMCB, UPR 9048, Pessac 33600, France.,Univ. Bordeaux, ICMCB, UPR 9048, Pessac 33600, France
| | - Høgni Weihe
- Department of Chemistry, University of Copenhagen, Copenhagen DK-2100, Denmark
| | - Zaher Salman
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, Villigen PSI CH-5232, Switzerland
| | - Thorbjørn J Morsing
- Department of Chemistry, University of Copenhagen, Copenhagen DK-2100, Denmark
| | | | - Yanhua Lan
- CNRS, Inst NEEL, Grenoble F-38000, France
| | | | - Corine Mathonière
- CNRS, ICMCB, UPR 9048, Pessac 33600, France.,Univ. Bordeaux, ICMCB, UPR 9048, Pessac 33600, France
| | - Stergios Piligkos
- Department of Chemistry, University of Copenhagen, Copenhagen DK-2100, Denmark
| | - Sophia I Klokishner
- Institute of Applied Physics, Academy of Sciences of Moldova, Kishinev 2028, Moldova
| | - Serghei Ostrovsky
- Institute of Applied Physics, Academy of Sciences of Moldova, Kishinev 2028, Moldova
| | - Katharina Ollefs
- ESRF - The European Synchrotron, CS 40220, 38043 Grenoble Cedex 9, France
| | - Fabrice Wilhelm
- ESRF - The European Synchrotron, CS 40220, 38043 Grenoble Cedex 9, France
| | - Andrei Rogalev
- ESRF - The European Synchrotron, CS 40220, 38043 Grenoble Cedex 9, France
| | - Rodolphe Clérac
- CNRS, ICMCB, UPR 9048, Pessac 33600, France.,Univ. Bordeaux, CRPP, UPR 8641, Pessac 33600, France
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53
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Song XY, You YZ, Balents L. Low-Energy Spin Dynamics of the Honeycomb Spin Liquid Beyond the Kitaev Limit. PHYSICAL REVIEW LETTERS 2016; 117:037209. [PMID: 27472139 DOI: 10.1103/physrevlett.117.037209] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Indexed: 06/06/2023]
Abstract
We investigate the generic features of the low energy dynamical spin structure factor of the Kitaev honeycomb quantum spin liquid perturbed away from its exact soluble limit by generic symmetry-allowed exchange couplings. We find that the spin gap persists in the Kitaev-Heisenberg model, but generally vanishes provided more generic symmetry-allowed interactions exist. We formulate the generic expansion of the spin operator in terms of fractionalized Majorana fermion operators according to the symmetry enriched topological order of the Kitaev spin liquid, described by its projective symmetry group. The dynamical spin structure factor displays power-law scaling bounded by Dirac cones in the vicinity of the Γ, K, and K^{'} points of the Brillouin zone, rather than the spin gap found for the exactly soluble point.
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Affiliation(s)
- Xue-Yang Song
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Yi-Zhuang You
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - Leon Balents
- Kavli Institute of Theoretical Physics, University of California, Santa Barbara, California 93106, USA
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54
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The vicinity of hyper-honeycomb β-Li2IrO3 to a three-dimensional Kitaev spin liquid state. Sci Rep 2016; 6:29585. [PMID: 27404112 PMCID: PMC4941717 DOI: 10.1038/srep29585] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 06/22/2016] [Indexed: 01/23/2023] Open
Abstract
Due to the combination of a substantial spin-orbit coupling and correlation effects, iridium oxides hold a prominent place in the search for novel quantum states of matter, including, e.g., Kitaev spin liquids and topological Weyl states. We establish the promise of the very recently synthesized hyper-honeycomb iridate β-Li2IrO3 in this regard. A detailed theoretical analysis reveals the presence of large ferromagnetic first-neighbor Kitaev interactions, while a second-neighbor antiferromagnetic Heisenberg exchange drives the ground state from ferro to zigzag order via a three-dimensional Kitaev spin liquid and an incommensurate phase. Experiment puts the system in the latter regime but the Kitaev spin liquid is very close and reachable by a slight modification of the ratio between the second- and first-neighbor couplings, for instance via strain.
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55
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Banerjee A, Bridges CA, Yan JQ, Aczel AA, Li L, Stone MB, Granroth GE, Lumsden MD, Yiu Y, Knolle J, Bhattacharjee S, Kovrizhin DL, Moessner R, Tennant DA, Mandrus DG, Nagler SE. Proximate Kitaev quantum spin liquid behaviour in a honeycomb magnet. NATURE MATERIALS 2016; 15:733-740. [PMID: 27043779 DOI: 10.1038/nmat4604] [Citation(s) in RCA: 210] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 02/22/2016] [Indexed: 06/05/2023]
Abstract
Quantum spin liquids (QSLs) are topological states of matter exhibiting remarkable properties such as the capacity to protect quantum information from decoherence. Whereas their featureless ground states have precluded their straightforward experimental identification, excited states are more revealing and particularly interesting owing to the emergence of fundamentally new excitations such as Majorana fermions. Ideal probes of these excitations are inelastic neutron scattering experiments. These we report here for a ruthenium-based material, α-RuCl3, continuing a major search (so far concentrated on iridium materials) for realizations of the celebrated Kitaev honeycomb topological QSL. Our measurements confirm the requisite strong spin-orbit coupling and low-temperature magnetic order matching predictions proximate to the QSL. We find stacking faults, inherent to the highly two-dimensional nature of the material, resolve an outstanding puzzle. Crucially, dynamical response measurements above interlayer energy scales are naturally accounted for in terms of deconfinement physics expected for QSLs. Comparing these with recent dynamical calculations involving gauge flux excitations and Majorana fermions of the pure Kitaev model, we propose the excitation spectrum of α-RuCl3 as a prime candidate for fractionalized Kitaev physics.
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Affiliation(s)
- A Banerjee
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - C A Bridges
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - J-Q Yan
- Material Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - A A Aczel
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - L Li
- Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - M B Stone
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - G E Granroth
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
- Neutron Data Analysis &Visualization Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - M D Lumsden
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - Y Yiu
- Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - J Knolle
- Department of Physics, Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - S Bhattacharjee
- Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany
- International Center for Theoretical Sciences, TIFR, Bangalore 560012, India
| | - D L Kovrizhin
- Department of Physics, Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - R Moessner
- Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany
| | - D A Tennant
- Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - D G Mandrus
- Material Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - S E Nagler
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
- Bredesen Center, University of Tennessee, Knoxville, Tennessee 37966, USA
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56
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Ezawa M. Loop-Nodal and Point-Nodal Semimetals in Three-Dimensional Honeycomb Lattices. PHYSICAL REVIEW LETTERS 2016; 116:127202. [PMID: 27058097 DOI: 10.1103/physrevlett.116.127202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Indexed: 06/05/2023]
Abstract
A honeycomb structure has a natural extension to three dimensions. Simple examples are hyperhoneycomb and stripy-honeycomb lattices, which are realized in β-Li_{2}IrO_{3} and γ-Li_{2}IrO_{3}, respectively. We propose a wide class of three-dimensional (3D) honeycomb lattices which are loop-nodal semimetals. Their edge states have intriguing properties similar to the two-dimensional honeycomb lattice in spite of a dimensional difference. Partial flat bands emerge at the zigzag or bearded edge of the 3D honeycomb lattice, whose boundary is given by the Fermi loop in the bulk spectrum. On the other hand, perfect flat bands emerge in the zigzag-bearded edge or when the anisotropy is large. The loop-nodal structure is destroyed once staggered potential or antiferromagnetic order is introduced. All these 3D honeycomb lattices become strong topological insulators with the inclusion of the spin-orbit interaction (SOI). Furthermore, point-nodal semimetals may be realized in the presence of both antiferromagnetic order and the SOI. We construct the effective four-band theory with the SOI to understand the physics near the Fermi level, based upon which the density of states and the dc conductivity are calculated.
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Affiliation(s)
- Motohiko Ezawa
- Department of Applied Physics, University of Tokyo, Hongo 7-3-1, 113-8656, Japan
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57
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Hermanns M, Trebst S, Rosch A. Spin-Peierls Instability of Three-Dimensional Spin Liquids with Majorana Fermi Surfaces. PHYSICAL REVIEW LETTERS 2015; 115:177205. [PMID: 26551141 DOI: 10.1103/physrevlett.115.177205] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Indexed: 06/05/2023]
Abstract
Three-dimensional (3D) variants of the Kitaev model can harbor gapless spin liquids with a Majorana Fermi surface on certain tricoordinated lattice structures such as the recently introduced hyperoctagon lattice. Here, we investigate Fermi surface instabilities arising from additional spin exchange terms (such as a Heisenberg coupling) which introduce interactions between the emergent Majorana fermion degrees of freedom. We show that independent of the sign and structure of the interactions, the Majorana surface is always unstable. Generically, the system spontaneously doubles its unit cell at exponentially small temperatures and forms a spin liquid with line nodes. Depending on the microscopics, further symmetries of the system can be broken at this transition. These spin-Peierls instabilities of a 3D spin liquid are closely related to BCS instabilities of fermions.
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Affiliation(s)
- Maria Hermanns
- Institute for Theoretical Physics, University of Cologne, 50937 Cologne, Germany
| | - Simon Trebst
- Institute for Theoretical Physics, University of Cologne, 50937 Cologne, Germany
| | - Achim Rosch
- Institute for Theoretical Physics, University of Cologne, 50937 Cologne, Germany
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58
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Hermanns M, O'Brien K, Trebst S. Weyl spin liquids. PHYSICAL REVIEW LETTERS 2015; 114:157202. [PMID: 25933336 DOI: 10.1103/physrevlett.114.157202] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Indexed: 06/04/2023]
Abstract
The fractionalization of quantum numbers in interacting quantum many-body systems is a central motif in condensed-matter physics with prominent examples including the fractionalization of the electron in quantum Hall liquids or the emergence of magnetic monopoles in spin-ice materials. Here, we discuss the fractionalization of magnetic moments in three-dimensional Kitaev models into Majorana fermions (and a Z_{2} gauge field) and their emergent collective behavior. We analytically demonstrate that the Majorana fermions form a Weyl superconductor for the Kitaev model on the recently synthesized hyperhoneycomb structure of β-Li_{2}IrO_{3} when applying a magnetic field. We characterize the topologically protected bulk and surface features of this state, which we dub a Weyl spin liquid, including thermodynamic and transport signatures.
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Affiliation(s)
- M Hermanns
- Institute for Theoretical Physics, University of Cologne, 50937 Cologne, Germany
| | - K O'Brien
- Institute for Theoretical Physics, University of Cologne, 50937 Cologne, Germany
| | - S Trebst
- Institute for Theoretical Physics, University of Cologne, 50937 Cologne, Germany
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59
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Schaffer R, Lee EKH, Lu YM, Kim YB. Topological spinon semimetals and gapless boundary states in three dimensions. PHYSICAL REVIEW LETTERS 2015; 114:116803. [PMID: 25839301 DOI: 10.1103/physrevlett.114.116803] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Indexed: 06/04/2023]
Abstract
Recently, there has been much effort in understanding topological phases of matter with gapless bulk excitations, which are characterized by topological invariants and protected intrinsic boundary states. Here we show that topological semimetals of Majorana fermions arise in exactly solvable Kitaev spin models on a series of three-dimensional lattices. The ground states of these models are quantum spin liquids with gapless nodal spectra of bulk Majorana fermion excitations. It is shown that these phases are topologically stable as long as certain discrete symmetries are protected. The corresponding topological indices and the gapless boundary states are explicitly computed to support these results. In contrast to previous studies of noninteracting systems, the phases discussed in this work are novel examples of gapless topological phases in interacting spin systems.
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Affiliation(s)
- Robert Schaffer
- Department of Physics and Center for Quantum Materials, University of Toronto, Toronto, Ontario M5S 1A7, Canada
| | - Eric Kin-Ho Lee
- Department of Physics and Center for Quantum Materials, University of Toronto, Toronto, Ontario M5S 1A7, Canada
| | - Yuan-Ming Lu
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Yong Baek Kim
- Department of Physics and Center for Quantum Materials, University of Toronto, Toronto, Ontario M5S 1A7, Canada
- School of Physics, Korea Institute for Advanced Study, Seoul 130-722, Korea
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60
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Wallace DC, McQueen TM. New honeycomb iridium(v) oxides: NaIrO3 and Sr3CaIr2O9. Dalton Trans 2015; 44:20344-51. [DOI: 10.1039/c5dt03188e] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two new honeycomb Ir5+ iridates are the first examples of a J = 0 state on a honeycomb lattice.
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Affiliation(s)
- David C. Wallace
- Department of Chemistry
- The Johns Hopkins University
- Baltimore
- USA
- Institute for Quantum Matter
| | - Tyrel M. McQueen
- Department of Chemistry
- The Johns Hopkins University
- Baltimore
- USA
- Institute for Quantum Matter
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61
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Nasu J, Udagawa M, Motome Y. Vaporization of Kitaev spin liquids. PHYSICAL REVIEW LETTERS 2014; 113:197205. [PMID: 25415923 DOI: 10.1103/physrevlett.113.197205] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Indexed: 06/04/2023]
Abstract
The quantum spin liquid is an exotic quantum state of matter in magnets. This state is a spin analog of liquid helium that does not solidify down to the lowest temperature due to strong quantum fluctuations. In conventional fluids, the liquid and gas possess the same symmetry and adiabatically connect to each other by bypassing the critical end point. We find that the situation is qualitatively different in quantum spin liquids realized in a three-dimensional Kitaev model; both gapless and gapped quantum spin liquid phases at low temperatures are always distinguished from the high-temperature paramagnet (spin gas) by a phase transition. The results challenge the common belief that the absence of thermodynamic singularity down to the lowest temperature is a symptom of a quantum spin liquid.
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Affiliation(s)
- Joji Nasu
- Department of Physics, Tokyo Institute of Technology, Ookayama, 2-12-1, Meguro, Tokyo 152-8551, Japan
| | - Masafumi Udagawa
- Department of Applied Physics, University of Tokyo, Hongo, 7-3-1, Bunkyo, Tokyo 113-8656, Japan
| | - Yukitoshi Motome
- Department of Applied Physics, University of Tokyo, Hongo, 7-3-1, Bunkyo, Tokyo 113-8656, Japan
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62
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Biffin A, Johnson RD, Kimchi I, Morris R, Bombardi A, Analytis JG, Vishwanath A, Coldea R. Noncoplanar and counterrotating incommensurate magnetic order stabilized by Kitaev interactions in γ-Li(2)IrO(3). PHYSICAL REVIEW LETTERS 2014; 113:197201. [PMID: 25415919 DOI: 10.1103/physrevlett.113.197201] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Indexed: 06/04/2023]
Abstract
Materials that realize Kitaev spin models with bond-dependent anisotropic interactions have long been searched for, as the resulting frustration effects are predicted to stabilize novel forms of magnetic order or quantum spin liquids. Here, we explore the magnetism of γ-Li(2)IrO(3), which has the topology of a three-dimensional Kitaev lattice of interconnected Ir honeycombs. Using magnetic resonant x-ray diffraction, we find a complex, yet highly symmetric incommensurate magnetic structure with noncoplanar and counterrotating Ir moments. We propose a minimal Kitaev-Heisenberg Hamiltonian that naturally accounts for all key features of the observed magnetic structure. Our results provide strong evidence that γ-Li(2)IrO(3) realizes a spin Hamiltonian with dominant Kitaev interactions.
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Affiliation(s)
- A Biffin
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - R D Johnson
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - I Kimchi
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - R Morris
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - A Bombardi
- Diamond Light Source Ltd., Didcot OX11 0DE, United Kingdom
| | - J G Analytis
- Department of Physics, University of California, Berkeley, California 94720, USA and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - A Vishwanath
- Department of Physics, University of California, Berkeley, California 94720, USA and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - R Coldea
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
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63
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Knolle J, Chern GW, Kovrizhin DL, Moessner R, Perkins NB. Raman scattering signatures of Kitaev spin liquids in A(2)IrO(3) iridates with A=Na or Li. PHYSICAL REVIEW LETTERS 2014; 113:187201. [PMID: 25396391 DOI: 10.1103/physrevlett.113.187201] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Indexed: 06/04/2023]
Abstract
We show how Raman spectroscopy can serve as a valuable tool for diagnosing quantum spin liquids (QSL). We find that the Raman response of the gapless QSL of the Kitaev-Heisenberg model exhibits signatures of spin fractionalization into Majorana fermions, which give rise to a broad signal reflecting their density of states, and Z(2) gauge fluxes, which also contribute a sharp feature. We discuss the current experimental situation and explore more generally the effect of breaking the integrability on response functions of Kitaev spin liquids.
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Affiliation(s)
- J Knolle
- Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany
| | - Gia-Wei Chern
- Center for Nonlinear Studies and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - D L Kovrizhin
- T.C.M. Group, Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom, and RRC Kurchatov Institute, 1 Kurchatov Square, Moscow 123182, Russia
| | - R Moessner
- Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany
| | - N B Perkins
- Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA and School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55116, USA
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