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Gu Y, Gu Y, Liu F, Ohira-Kawamura S, Murai N, Zhao J. Signatures of Kitaev Interactions in the van der Waals Ferromagnet VI_{3}. PHYSICAL REVIEW LETTERS 2024; 132:246702. [PMID: 38949369 DOI: 10.1103/physrevlett.132.246702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 04/30/2024] [Accepted: 05/10/2024] [Indexed: 07/02/2024]
Abstract
Materials manifesting the Kitaev model, characterized by bond-dependent interactions on a honeycomb lattice, can host exotic phenomena like quantum spin liquid states and topological magnetic excitations. However, finding such materials remains a formidable challenge. Here, we report high-resolution inelastic neutron scattering measurements performed on VI_{3}, a van der Waals ferromagnetic Mott insulator, covering a wide range of reciprocal space. Our measurements unveil highly anisotropic magnetic excitations in momentum space. Through a comprehensive comparative analysis of various models that incorporate diverse symmetry-allowed magnetic interactions, we find the observed excitations are well captured by a model with a large bond-dependent Kitaev interaction. These results not only help to understand the intriguing properties of VI_{3}, such as the pronounced anomalous thermal Hall effects and strong pressure or structure dependence of magnetism, but also open a new avenue for exploring Kitaev physics.
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Affiliation(s)
- Yiqing Gu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | | | | | | | | | - Jun Zhao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
- Institute of Nanoelectronics and Quantum Computing, Fudan University, Shanghai 200433, China
- Shanghai Branch, Hefei National Laboratory, Shanghai 201315, China
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2
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Rousochatzakis I, Perkins NB, Luo Q, Kee HY. Beyond Kitaev physics in strong spin-orbit coupled magnets. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2024; 87:026502. [PMID: 38241723 DOI: 10.1088/1361-6633/ad208d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 01/19/2024] [Indexed: 01/21/2024]
Abstract
We review the recent advances and current challenges in the field of strong spin-orbit coupled Kitaev materials, with a particular emphasis on the physics beyond the exactly-solvable Kitaev spin liquid point. To this end, we present a comprehensive overview of the key exchange interactions in candidate materials with a specific focus on systems featuring effectiveJeff=1/2magnetic moments. This includes, but not limited to,5d5iridates,4d5ruthenates and3d7cobaltates. Our exploration covers the microscopic origins of these interactions, along with a systematic attempt to map out the most intriguing correlated regimes of the multi-dimensional parameter space. Our approach is guided by robust symmetry and duality transformations as well as insights from a wide spectrum of analytical and numerical studies. We also survey higher spin Kitaev models and recent exciting results on quasi-one-dimensional models and discuss their relevance to higher-dimensional models. Finally, we highlight some of the key questions in the field as well as future directions.
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Affiliation(s)
| | - Natalia B Perkins
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, United States of America
- Technical University of Munich, Munich, Germany
- Institute for Advanced Study, D-85748 Garching, Germany
| | - Qiang Luo
- College of Physics, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, People's Republic of China
- Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada
| | - Hae-Young Kee
- Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada
- Canadian Institute for Advanced Research, CIFAR Program in Quantum Materials, Toronto, Ontario M5G 1M1, Canada
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3
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Samanta S, Hong D, Kim HS. Electronic Structures of Kitaev Magnet Candidates RuCl 3 and RuI 3. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 14:9. [PMID: 38202464 PMCID: PMC10780606 DOI: 10.3390/nano14010009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 12/13/2023] [Accepted: 12/18/2023] [Indexed: 01/12/2024]
Abstract
Layered honeycomb magnets with strong atomic spin-orbit coupling at transition metal sites have been intensively studied for the search of Kitaev magnetism and the resulting non-Abelian braiding statistics. α-RuCl3 has been the most promising candidate, and there have been several reports on the realization of sibling compounds α-RuBr3 and α-RuI3 with the same crystal structure. Here, we investigate correlated electronic structures of α-RuCl3 and α-RuI3 by employing first-principles dynamical mean-field theory. Our result provides a valuable insight into the discrepancy between experimental and theoretical reports on transport properties of α-RuI3, and suggests a potential realization of correlated flat bands with strong spin-orbit coupling and a quantum spin-Hall insulating phase in α-RuI3.
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Affiliation(s)
- Subhasis Samanta
- Department of Physics, Kangwon National University, Chuncheon 24341, Republic of Korea; (S.S.); (D.H.)
| | - Dukgeun Hong
- Department of Physics, Kangwon National University, Chuncheon 24341, Republic of Korea; (S.S.); (D.H.)
| | - Heung-Sik Kim
- Department of Physics, Kangwon National University, Chuncheon 24341, Republic of Korea; (S.S.); (D.H.)
- Institute of Quantum Convergence and Technology, Kangwon National University, Chuncheon 24341, Republic of Korea
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Xiang L, Dhakal R, Ozerov M, Jiang Y, Mou BS, Ozarowski A, Huang Q, Zhou H, Fang J, Winter SM, Jiang Z, Smirnov D. Disorder-Enriched Magnetic Excitations in a Heisenberg-Kitaev Quantum Magnet Na_{2}Co_{2}TeO_{6}. PHYSICAL REVIEW LETTERS 2023; 131:076701. [PMID: 37656855 DOI: 10.1103/physrevlett.131.076701] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 07/31/2023] [Accepted: 08/03/2023] [Indexed: 09/03/2023]
Abstract
Using optical magnetospectroscopy, we investigate the magnetic excitations of Na_{2}Co_{2}TeO_{6} in a broad magnetic field range (0 T≤B≤17.5 T) at low temperature. Our measurements reveal rich spectra of in-plane magnetic excitations with a surprisingly large number of modes, even in the high-field spin-polarized state. Theoretical calculations find that the Na-occupation disorder in Na_{2}Co_{2}TeO_{6} plays a crucial role in generating these modes. Our Letter demonstrates the necessity to consider disorder in the spin environment in the search for Kitaev quantum spin liquid states in practicable materials.
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Affiliation(s)
- Li Xiang
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
| | - Ramesh Dhakal
- Department of Physics and Center for Functional Materials, Wake Forest University, Winston-Salem, North Carolina 27109, USA
| | - Mykhaylo Ozerov
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
| | - Yuxuan Jiang
- School of Physics and Optoelectronics, Anhui University, Hefei, Anhui 230601, China
- Center of Free Electron Laser and High Magnetic Field, Anhui University, Hefei 230601, China
| | - Banasree S Mou
- Department of Physics and Center for Functional Materials, Wake Forest University, Winston-Salem, North Carolina 27109, USA
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
| | - Qing Huang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Haidong Zhou
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Jiyuan Fang
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Stephen M Winter
- Department of Physics and Center for Functional Materials, Wake Forest University, Winston-Salem, North Carolina 27109, USA
| | - Zhigang Jiang
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Dmitry Smirnov
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
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Zhang X, Xu Y, Halloran T, Zhong R, Broholm C, Cava RJ, Drichko N, Armitage NP. A magnetic continuum in the cobalt-based honeycomb magnet BaCo 2(AsO 4) 2. NATURE MATERIALS 2023; 22:58-63. [PMID: 36411349 DOI: 10.1038/s41563-022-01403-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
Quantum spin liquids (QSLs) are topologically ordered states of matter that host fractionalized excitations. A particular route towards a QSL is via strongly bond-dependent interactions on the hexagonal lattice. A number of Ru- and Ir-based candidate Kitaev QSL materials have been pursued, but all have appreciable non-Kitaev interactions. Using time-domain terahertz spectroscopy, we observed a broad magnetic continuum over a wide range of temperatures and fields in the honeycomb cobalt-based magnet BaCo2(AsO4)2, which has been proposed to be a more ideal version of a Kitaev QSL. Applying an in-plane magnetic field of ~0.5 T suppresses the magnetic order, and at higher fields, applying the field gives rise to a spin-polarized state. Under a 4 T magnetic field that was oriented principally out of plane, a broad magnetic continuum was observed that may be consistent with a field-induced QSL. Our results indicate BaCo2(AsO4)2 is a promising QSL candidate.
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Affiliation(s)
- Xinshu Zhang
- Institute for Quantum Matter, Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA
| | - Yuanyuan Xu
- Institute for Quantum Matter, Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA
| | - T Halloran
- Institute for Quantum Matter, Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA
| | - Ruidan Zhong
- Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - C Broholm
- Institute for Quantum Matter, Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - R J Cava
- Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - N Drichko
- Institute for Quantum Matter, Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA
| | - N P Armitage
- Institute for Quantum Matter, Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA.
- Canadian Institute for Advanced Research, Toronto, Ontario, Canada.
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Yao W, Iida K, Kamazawa K, Li Y. Excitations in the Ordered and Paramagnetic States of Honeycomb Magnet Na_{2}Co_{2}TeO_{6}. PHYSICAL REVIEW LETTERS 2022; 129:147202. [PMID: 36240411 DOI: 10.1103/physrevlett.129.147202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 09/13/2022] [Indexed: 06/16/2023]
Abstract
Na_{2}Co_{2}TeO_{6} is a proposed approximate Kitaev magnet, yet its actual magnetic interactions are elusive due to a lack of knowledge on the full excitation spectrum. Here, using inelastic neutron scattering and single crystals, we determine the system's temperature-dependent magnetic excitations over the entire Brillouin zone. Without committing to specific models, we unveil a distinct signature of the third-nearest-neighbor coupling in the spin waves, which signifies the associated distance as an emerging effective link in the ordered state. The presence of at least six nonoverlapping spin-wave branches is at odds with all models proposed to date. Above the ordering temperature, persisting dynamic correlations can be described by equal-time magnetic structure factors of a hexagonal cluster, which reveal the leading instabilities. Our result sets definitive constraints on theoretical models for Na_{2}Co_{2}TeO_{6} and provides new insight for the materialization of the Kitaev model.
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Affiliation(s)
- Weiliang Yao
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Kazuki Iida
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, Tokai, Ibaraki 319-1106, Japan
| | - Kazuya Kamazawa
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, Tokai, Ibaraki 319-1106, Japan
| | - Yuan Li
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
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