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Maksimov PA, Ushakov AV, Gubkin AF, Redhammer GJ, Winter SM, Kolesnikov AI, Dos Santos AM, Gai Z, McGuire MA, Podlesnyak A, Streltsov SV. Cobalt-based pyroxenes: A new playground for Kitaev physics. Proc Natl Acad Sci U S A 2024; 121:e2409154121. [PMID: 39423242 DOI: 10.1073/pnas.2409154121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Accepted: 09/19/2024] [Indexed: 10/21/2024] Open
Abstract
Recent advances in the study of cobaltites have unveiled their potential as a promising platform for realizing Kitaev physics in honeycomb systems and the Ising model in weakly coupled chain materials. In this manuscript, we explore the magnetic properties of pyroxene SrCoGe[Formula: see text]O[Formula: see text] using a combination of neutron scattering, ab initio methods, and linear spin-wave theory. Through careful examination of inelastic neutron scattering powder spectra, we propose a modified Kitaev model to accurately describe the twisted chains of edge-sharing octahedra surrounding Co[Formula: see text] ions. The extended Kitaev-Heisenberg model, including a significant anisotropic bond-dependent exchange term with [Formula: see text], is identified as the key descriptor of the magnetic interactions in SrCoGe[Formula: see text]O[Formula: see text]. Furthermore, our heat capacity measurements reveal an effect of an external magnetic field (approximately 13 T) which shifts the system from a fragile antiferromagnetic ordering with [Formula: see text] K to a field-induced state. We argue that pyroxenes, particularly those modified by substituting Ge with Si and its less extended [Formula: see text] orbitals, emerge as a platform for the Kitaev model. This opens up possibilities for advancing our understanding of Kitaev physics.
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Affiliation(s)
- Pavel A Maksimov
- Bogolyubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Moscow region 141980, Russia
- M. N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, Ekaterinburg 620990, Russia
| | - Alexey V Ushakov
- M. N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, Ekaterinburg 620990, Russia
| | - Andrey F Gubkin
- M. N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, Ekaterinburg 620990, Russia
- Institute of Natural Sciences and Mathematics, Ural Federal University, Ekaterinburg 620002, Russia
| | - Günther J Redhammer
- Department of Chemistry and Physics of Materials, University of Salzburg, Salzburg A-5020, Austria
| | - Stephen M Winter
- Department of Physics and Center for Functional Materials, Wake Forest University, Winston-Salem, NC27109
| | | | | | - Zheng Gai
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831
| | - Michael A McGuire
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
| | - Andrey Podlesnyak
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
| | - Sergey V Streltsov
- M. N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, Ekaterinburg 620990, Russia
- Department of Theoretical Physics and Applied Mathematics, Ural Federal University, Ekaterinburg 620002, Russia
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2
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Yu Z, Liang H, Wang Y, Li N, Sun Y, Wu D, Zhou Y, Ding Z, Sun J, He T, Wu Z, Wang J, Sun X, Li Q. Low-temperature magnetic properties of the S= 1/2 kagomé antiferromagnet YCo 3(OH) 6.55Br 2.45. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:495602. [PMID: 39191272 DOI: 10.1088/1361-648x/ad7434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 08/27/2024] [Indexed: 08/29/2024]
Abstract
We report the synthesis, crystal structure, magnetization and specific heat studies of YCo3(OH)6.55Br2.45single crystal. YCo3(OH)6.55Br2.45crystallizes in trigonal structure, in which Co2+ions form a perfect kagomé lattice. The magnetic susceptibility reveals successive magnetic transitions at 6.5 and 7.8 K and the Curie-Weiss fitting demonstrates that YCo3(OH)6.55Br2.45has strong antiferromagnetic coupling and pronounced magnetic frustration effect. Specific heat data suggest that low-Tmagnetic transitions are attributed to antiferromagnetic ordering of Co2+ions and the magnetic entropy points to effective 1/2 spin in the system. These results indicate that an unusual magnetic ordering state with effective spin-1/2 is realized in kagomé lattice system YCo3(OH)6.55Br2.45.
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Affiliation(s)
- Zhenwei Yu
- School of Materials Science and Engineering, Anhui University, Hefei 230601, People's Republic of China
| | - Hui Liang
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
| | - Yiyan Wang
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
| | - Na Li
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
| | - Yan Sun
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
| | - Dandan Wu
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
| | - Ying Zhou
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
| | - Zongling Ding
- School of Physics and Optoelectronic engineering, Anhui University, Hefei 230601, People's Republic of China
| | - Jin Sun
- School of Physics and Optoelectronic engineering, Anhui University, Hefei 230601, People's Republic of China
| | - Tianbo He
- School of Physics and Optoelectronic engineering, Anhui University, Hefei 230601, People's Republic of China
| | - Ziyang Wu
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, Hubei 430074, People's Republic of China
| | - Junfeng Wang
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, Hubei 430074, People's Republic of China
| | - Xuefeng Sun
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
| | - Qiuju Li
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
- School of Physics and Optoelectronic engineering, Anhui University, Hefei 230601, People's Republic of China
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3
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Li H, Lv E, Xi N, Gao Y, Qi Y, Li W, Su G. Magnetocaloric effect of topological excitations in Kitaev magnets. Nat Commun 2024; 15:7011. [PMID: 39147763 PMCID: PMC11327298 DOI: 10.1038/s41467-024-51146-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 07/29/2024] [Indexed: 08/17/2024] Open
Abstract
Traditional magnetic sub-Kelvin cooling relies on the nearly free local moments in hydrate paramagnetic salts, whose utility is hampered by the dilute magnetic ions and low thermal conductivity. Here we propose to use instead fractional excitations inherent to quantum spin liquids (QSLs) as an alternative, which are sensitive to external fields and can induce a very distinctive magnetocaloric effect. With state-of-the-art tensor-network approach, we compute low-temperature properties of Kitaev honeycomb model. For the ferromagnetic case, strong demagnetization cooling effect is observed due to the nearly free Z2 vortices via spin fractionalization, described by a paramagnetic equation of state with a renormalized Curie constant. For the antiferromagnetic Kitaev case, we uncover an intermediate-field gapless QSL phase with very large spin entropy, possibly due to the emergence of spinon Fermi surface and gauge field. Potential realization of topological excitation magnetocalorics in Kitaev materials is also discussed, which may offer a promising pathway to circumvent existing limitations in the paramagnetic hydrates.
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Affiliation(s)
- Han Li
- Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
- Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Enze Lv
- Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Ning Xi
- Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Yuan Gao
- Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Peng Huanwu Collaborative Center for Research and Education, and School of Physics, Beihang University, Beijing, 100191, China
| | - Yang Qi
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Wei Li
- Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- Peng Huanwu Collaborative Center for Research and Education, and School of Physics, Beihang University, Beijing, 100191, China.
| | - Gang Su
- Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China.
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4
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Kim GH, Park M, Samanta S, Choi U, Kang B, Seo U, Ji G, Noh S, Cho DY, Yoo JW, Ok JM, Kim HS, Sohn C. Suppression of antiferromagnetic order by strain-enhanced frustration in honeycomb cobaltate. SCIENCE ADVANCES 2024; 10:eadn8694. [PMID: 38968350 PMCID: PMC11225782 DOI: 10.1126/sciadv.adn8694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 06/04/2024] [Indexed: 07/07/2024]
Abstract
Layered honeycomb cobaltates are predicted as promising for realizing the Kitaev quantum spin liquid, a many-body quantum entangled ground state characterized by fractional excitations. However, they exhibit antiferromagnetic ordering at low temperatures, hindering the expected quantum state. We demonstrate that controlling the trigonal distortion of CoO6 octahedra is crucial to suppress antiferromagnetic order through enhancing frustration in layered honeycomb cobaltates. Using heterostructure engineering on Cu3Co2SbO6 thin films, we adjust the trigonal distortion of CoO6 octahedra and the resulting trigonal crystal field. The original Néel temperature of 16 kelvin in bulk Cu3Co2SbO6 decreases (increases) to 7.8 kelvin (22.7 kelvin) in strained Cu3Co2SbO6 films by decreasing (increasing) the magnitude of the trigonal crystal fields. The first-principles calculation suggests the enhancement of geometrical frustration as the origin of the suppression of antiferromagnetism. This finding supports the potential of layered honeycomb cobaltate heterostructures and strain engineering in realizing extremely elusive quantum phases of matter.
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Affiliation(s)
- Gye-Hyeon Kim
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Miju Park
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Subhasis Samanta
- Department of Semiconductor Physics and Institute of Quantum Convergence Technology, Kangwon National University, Chuncheon 24341, Republic of Korea
- Center for Extreme Quantum Matter and Functionality, Sungkyunkwan University, Suwon 16419 Republic of Korea
| | - Uksam Choi
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Baekjune Kang
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Uihyeon Seo
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - GwangCheol Ji
- Department of Physics, Pusan National University, Busan 46241, Republic of Korea
| | - Seunghyeon Noh
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Deok-Yong Cho
- Department of Physics, Jeonbuk National University, Jeonju 54896, Republic of Korea
| | - Jung-Woo Yoo
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Jong Mok Ok
- Department of Physics, Pusan National University, Busan 46241, Republic of Korea
| | - Heung-Sik Kim
- Department of Semiconductor Physics and Institute of Quantum Convergence Technology, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - Changhee Sohn
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
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5
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Cookmeyer T, Das Sarma S. Engineering the Kitaev Spin Liquid in a Quantum Dot System. PHYSICAL REVIEW LETTERS 2024; 132:186501. [PMID: 38759190 DOI: 10.1103/physrevlett.132.186501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 02/22/2024] [Accepted: 03/29/2024] [Indexed: 05/19/2024]
Abstract
The Kitaev model on a honeycomb lattice may provide a robust topological quantum memory platform, but finding a material that realizes the unique spin-liquid phase remains a considerable challenge. We demonstrate that an effective Kitaev Hamiltonian can arise from a half-filled Fermi-Hubbard Hamiltonian where each site can experience a magnetic field in a different direction. As such, we provide a method for realizing the Kitaev spin liquid on a single hexagonal plaquette made up of 12 quantum dots. Despite the small system size, there are clear signatures of the Kitaev spin-liquid ground state, and there is a range of parameters where these signatures are predicted, allowing a potential platform where Kitaev spin-liquid physics can be explored experimentally in quantum dot plaquettes.
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Affiliation(s)
- Tessa Cookmeyer
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106-4030, USA
| | - Sankar Das Sarma
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106-4030, USA
- Condensed Matter Theory Center and Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA
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6
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Chen L, Lefrançois É, Vallipuram A, Barthélemy Q, Ataei A, Yao W, Li Y, Taillefer L. Planar thermal Hall effect from phonons in a Kitaev candidate material. Nat Commun 2024; 15:3513. [PMID: 38664403 PMCID: PMC11045815 DOI: 10.1038/s41467-024-47858-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
The thermal Hall effect has emerged as a potential probe of exotic excitations in spin liquids. In the Kitaev magnet α -RuCl3, the thermal Hall conductivityκ x y has been attributed to Majorana fermions, chiral magnons, or phonons. Theoretically, the former two types of heat carriers can generate a "planar"κ x y , whereby the magnetic field is parallel to the heat current, but it is unknown whether phonons also could. Here we show that a planarκ x y is present in another Kitaev candidate material, Na2Co2TeO6. Based on the striking similarity betweenκ x y and the phonon-dominated thermal conductivityκ x x , we attribute the effect to phonons. We observe a large difference inκ x y between different configurations of heat current and magnetic field, which reveals that the direction of heat current matters in determining the planarκ x y . Our observation calls for a re-evaluation of the planarκ x y observed inα -RuCl3.
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Affiliation(s)
- Lu Chen
- Institut quantique, Département de physique & RQMP, Université de Sherbrooke, Sherbrooke, QC, Canada.
| | - Étienne Lefrançois
- Institut quantique, Département de physique & RQMP, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Ashvini Vallipuram
- Institut quantique, Département de physique & RQMP, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Quentin Barthélemy
- Institut quantique, Département de physique & RQMP, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Amirreza Ataei
- Institut quantique, Département de physique & RQMP, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Weiliang Yao
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
| | - Yuan Li
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
| | - Louis Taillefer
- Institut quantique, Département de physique & RQMP, Université de Sherbrooke, Sherbrooke, QC, Canada.
- Canadian Institute for Advanced Research, Toronto, ON, Canada.
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7
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Qian N, Gao X, Lang X, Deng H, Bratu TM, Chen Q, Stapleton P, Yan B, Min W. Rapid single-particle chemical imaging of nanoplastics by SRS microscopy. Proc Natl Acad Sci U S A 2024; 121:e2300582121. [PMID: 38190543 PMCID: PMC10801917 DOI: 10.1073/pnas.2300582121] [Citation(s) in RCA: 47] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 10/24/2023] [Indexed: 01/10/2024] Open
Abstract
Plastics are now omnipresent in our daily lives. The existence of microplastics (1 µm to 5 mm in length) and possibly even nanoplastics (<1 μm) has recently raised health concerns. In particular, nanoplastics are believed to be more toxic since their smaller size renders them much more amenable, compared to microplastics, to enter the human body. However, detecting nanoplastics imposes tremendous analytical challenges on both the nano-level sensitivity and the plastic-identifying specificity, leading to a knowledge gap in this mysterious nanoworld surrounding us. To address these challenges, we developed a hyperspectral stimulated Raman scattering (SRS) imaging platform with an automated plastic identification algorithm that allows micro-nano plastic analysis at the single-particle level with high chemical specificity and throughput. We first validated the sensitivity enhancement of the narrow band of SRS to enable high-speed single nanoplastic detection below 100 nm. We then devised a data-driven spectral matching algorithm to address spectral identification challenges imposed by sensitive narrow-band hyperspectral imaging and achieve robust determination of common plastic polymers. With the established technique, we studied the micro-nano plastics from bottled water as a model system. We successfully detected and identified nanoplastics from major plastic types. Micro-nano plastics concentrations were estimated to be about 2.4 ± 1.3 × 105 particles per liter of bottled water, about 90% of which are nanoplastics. This is orders of magnitude more than the microplastic abundance reported previously in bottled water. High-throughput single-particle counting revealed extraordinary particle heterogeneity and nonorthogonality between plastic composition and morphologies; the resulting multidimensional profiling sheds light on the science of nanoplastics.
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Affiliation(s)
- Naixin Qian
- Department of Chemistry, Columbia University, New York, NY10027
| | - Xin Gao
- Department of Chemistry, Columbia University, New York, NY10027
| | - Xiaoqi Lang
- Department of Chemistry, Columbia University, New York, NY10027
| | - Huiping Deng
- Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY10964
| | | | - Qixuan Chen
- Department of Biostatistics, Columbia University Mailman School of Public Health, New York, NY10032
| | - Phoebe Stapleton
- Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Environmental and Occupational Health Sciences Institute, Rutgers University, New Brunswick, NJ08854
| | - Beizhan Yan
- Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY10964
| | - Wei Min
- Department of Chemistry, Columbia University, New York, NY10027
- Department of Biomedical Engineering, Columbia University, New York, NY10027
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8
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Xu X, Hao Y, Peng S, Zhang Q, Ni D, Yang C, Dai X, Cao H, Cava RJ. Large off-diagonal magnetoelectricity in a triangular Co 2+-based collinear antiferromagnet. Nat Commun 2023; 14:8034. [PMID: 38052828 DOI: 10.1038/s41467-023-43858-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 11/22/2023] [Indexed: 12/07/2023] Open
Abstract
Magnetic toroidicity is an uncommon type of magnetic structure in solid-state materials. Here, we experimentally demonstrate that collinear spins in a material with R-3 lattice symmetry can host a significant magnetic toroidicity, even parallel to the ordered spins. Taking advantage of a single crystal sample of CoTe6O13 with an R-3 space group and a Co2+ triangular sublattice, temperature-dependent magnetic, thermodynamic, and neutron diffraction results reveal A-type antiferromagnetic order below 19.5 K, with magnetic point group -3' and k = (0,0,0). Our symmetry analysis suggests that the missing mirror symmetry in the lattice could lead to the local spin canting for a toroidal moment along the c axis. Experimentally, we observe a large off-diagonal magnetoelectric coefficient of 41.2 ps/m that evidences the magnetic toroidicity. In addition, the paramagnetic state exhibits a large effective moment per Co2+, indicating that the magnetic moment in CoTe6O13 has a significant orbital contribution. CoTe6O13 embodies an excellent opportunity for the study of next-generation functional magnetoelectric materials.
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Affiliation(s)
- Xianghan Xu
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA.
| | - Yiqing Hao
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Shiyu Peng
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - Qiang Zhang
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Danrui Ni
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Chen Yang
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Xi Dai
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - Huibo Cao
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - R J Cava
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA.
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9
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Krüger WGF, Chen W, Jin X, Li Y, Janssen L. Triple-q Order in Na_{2}Co_{2}TeO_{6} from Proximity to Hidden-SU(2)-Symmetric Point. PHYSICAL REVIEW LETTERS 2023; 131:146702. [PMID: 37862642 DOI: 10.1103/physrevlett.131.146702] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 08/18/2023] [Indexed: 10/22/2023]
Abstract
In extended Heisenberg-Kitaev-Gamma-type spin models, hidden-SU(2)-symmetric points are isolated points in parameter space that can be mapped to pure Heisenberg models via nontrivial duality transformations. Such points generically feature quantum degeneracy between conventional single-q and exotic multi-q states. We argue that recent single-crystal inelastic neutron scattering data place the honeycomb magnet Na_{2}Co_{2}TeO_{6} in proximity to such a hidden-SU(2)-symmetric point. The low-temperature order is identified as a triple-q state arising from the Néel antiferromagnet with staggered magnetization in the out-of-plane direction via a 4-sublattice duality transformation. This state naturally explains various distinctive features of the magnetic excitation spectrum, including its surprisingly high symmetry and the dispersive low-energy and flat high-energy bands. Our result demonstrates the importance of bond-dependent exchange interactions in cobaltates, and illustrates the intriguing magnetic behavior resulting from them.
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Affiliation(s)
- Wilhelm G F Krüger
- Institut für Theoretische Physik and Würzburg-Dresden Cluster of Excellence ct.qmat, TU Dresden, 01062 Dresden, Germany
| | - Wenjie Chen
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Xianghong Jin
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Yuan Li
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Lukas Janssen
- Institut für Theoretische Physik and Würzburg-Dresden Cluster of Excellence ct.qmat, TU Dresden, 01062 Dresden, Germany
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10
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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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11
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Halloran T, Desrochers F, Zhang EZ, Chen T, Chern LE, Xu Z, Winn B, Graves-Brook M, Stone MB, Kolesnikov AI, Qiu Y, Zhong R, Cava R, Kim YB, Broholm C. Geometrical frustration versus Kitaev interactions in BaCo 2(AsO 4) 2. Proc Natl Acad Sci U S A 2023; 120:e2215509119. [PMID: 36608295 PMCID: PMC9926200 DOI: 10.1073/pnas.2215509119] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 11/04/2022] [Indexed: 01/07/2023] Open
Abstract
Recently, Co-based honeycomb magnets have been proposed as promising candidate materials to host the Kitaev spin liquid (KSL) state. One of the front-runners is BaCo2(AsO4)2 (BCAO), where it was suggested that the exchange processes between Co2+ ions via the surrounding edge-sharing oxygen octahedra could give rise to bond-dependent Kitaev interactions. In this work, we present and analyze a comprehensive inelastic neutron scattering (INS) study of BCAO with fields in the honeycomb plane. Combining the constraints from the magnon excitations in the high-field polarized state and the inelastic spin structure factor measured in zero magnetic field, we examine two leading theoretical models: the Kitaev-type [Formula: see text] model and the XXZ[Formula: see text]model. We show that the existing experimental data can be consistently accounted for by the XXZ[Formula: see text]model but not by the [Formula: see text] model, and we discuss the implications of these results for the realization of a spin liquid phase in BCAO and more generally for the realization of the Kitaev model in cobaltates.
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Affiliation(s)
- Thomas Halloran
- Institute for Quantum Matter, Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD21218
| | - Félix Desrochers
- Department of Physics, University of Toronto, TorontoON M5S 1A7, Canada
| | - Emily Z. Zhang
- Department of Physics, University of Toronto, TorontoON M5S 1A7, Canada
| | - Tong Chen
- Institute for Quantum Matter, Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD21218
| | - Li Ern Chern
- Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, CambridgeCB3 0HE, United Kingdom
| | - Zhijun Xu
- National Institute of Standards and Technology, Center for Neutron Research, Gaithersburg, MD20899
- Department of Materials Science and Engineering, University of Maryland, College Park, MD20742
| | - Barry Winn
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN37831
| | - M. Graves-Brook
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN37831
| | - M. B. Stone
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN37831
| | | | - Yiming Qiu
- National Institute of Standards and Technology, Center for Neutron Research, Gaithersburg, MD20899
| | - Ruidan Zhong
- Department of Chemistry, Princeton University, Princeton, NJ08544
- Tsung-Dao Lee Institute, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai200240, China
| | - Robert Cava
- Department of Chemistry, Princeton University, Princeton, NJ08544
| | - Yong Baek Kim
- Department of Physics, University of Toronto, TorontoON M5S 1A7, Canada
| | - Collin Broholm
- Institute for Quantum Matter, Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD21218
- Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, MD21218
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12
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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: 6] [Impact Index Per Article: 6.0] [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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13
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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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14
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Duan Q, Bu H, Pomjakushin V, Luetkens H, Li Y, Zhao J, Gardner JS, Guo H. Anomalous Ferromagnetic Behavior in Orthorhombic Li 3Co 2SbO 6. Inorg Chem 2022; 61:10880-10887. [DOI: 10.1021/acs.inorgchem.2c01293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Qianhui Duan
- School of Physics and Hangzhou Key Laboratory of Quantum Matters, Hangzhou Normal University, Hangzhou 311121, China
- Neutron Science Platform, Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Huanpeng Bu
- Neutron Science Platform, Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Vladimir Pomjakushin
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Hubertus Luetkens
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Yuke Li
- School of Physics and Hangzhou Key Laboratory of Quantum Matters, Hangzhou Normal University, Hangzhou 311121, China
| | - Jinkui Zhao
- Neutron Science Platform, Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Jason S. Gardner
- Material Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Hanjie Guo
- Neutron Science Platform, Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
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15
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Kim C, Kim HS, Park JG. Spin-orbital entangled state and realization of Kitaev physics in 3 dcobalt compounds: a progress report. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 34:023001. [PMID: 34614480 DOI: 10.1088/1361-648x/ac2d5d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 10/06/2021] [Indexed: 06/13/2023]
Abstract
The realization of Kitaev's honeycomb magnetic model in real materials has become one of the most pursued topics in condensed matter physics and materials science. If found, it is expected to host exotic quantum phases of matter and offers potential realizations of fault-tolerant quantum computations. Over the past years, much effort has been made on 4d- or 5d-heavy transition metal compounds because of their intrinsic strong spin-orbit coupling. But more recently, there have been growing shreds of evidence that the Kitaev model could also be realized in 3d-transition metal systems with much weaker spin-orbit coupling. This review intends to serve as a guide to this fast-developing field focusing on systems withd7transition metal occupation. It overviews the current theoretical and experimental progress on realizing the Kitaev model in those systems. We examine the recent experimental observations of candidate materials with Co2+ions: e.g., CoPS3, Na3Co2SbO6, and Na2Co2TeO6, followed by a brief review of theoretical backgrounds. We conclude this article by comparing experimental observations with density functional theory calculations. We stress the importance of inter-t2ghopping channels and Hund's coupling in the realization of Kitaev interactions in Co-based compounds, which has been overlooked in previous studies. This review suggests future directions in the search for Kitaev physics in 3dcobalt compounds and beyond.
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Affiliation(s)
- Chaebin Kim
- Center for Quantum Materials, Seoul National University, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Heung-Sik Kim
- Department of Physics and Institute for Accelerator Science, Kangwon National University, Chuncheon 24311, Republic of Korea
| | - Je-Geun Park
- Center for Quantum Materials, Seoul National University, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
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