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Zvyagin SA, Ponomaryov AN, Wosnitza J, Hirai D, Hiroi Z, Gen M, Kohama Y, Matsuo A, Matsuda YH, Kindo K. Dimensional reduction and incommensurate dynamic correlations in the [Formula: see text] triangular-lattice antiferromagnet Ca 3ReO 5Cl 2. Nat Commun 2022; 13:6310. [PMID: 36274086 PMCID: PMC9588769 DOI: 10.1038/s41467-022-33992-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 10/07/2022] [Indexed: 12/03/2022] Open
Abstract
The observation of spinon excitations in the [Formula: see text] triangular antiferromagnet Ca3ReO5Cl2 reveals a quasi-one-dimensional (1D) nature of magnetic correlations, in spite of the nominally 2D magnetic structure. This phenomenon is known as frustration-induced dimensional reduction. Here, we present high-field electron spin resonance spectroscopy and magnetization studies of Ca3ReO5Cl2, allowing us not only to refine spin-Hamiltonian parameters, but also to investigate peculiarities of its low-energy spin dynamics. We argue that the presence of the uniform Dzyaloshinskii-Moriya interaction (DMI) shifts the spinon continuum in momentum space and, as a result, opens a zero-field gap at the Γ point. We observed this gap directly. The shift is found to be consistent with the structural modulation in the ordered state, suggesting this material as a perfect model triangular-lattice system, where a pure DMI-spiral ground state can be realized.
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Affiliation(s)
- S. A. Zvyagin
- Dresden High Magnetic Field Laboratory (HLD-EMFL) and Würzburg-Dresden Cluster of Excellence ct.qmat, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - A. N. Ponomaryov
- Dresden High Magnetic Field Laboratory (HLD-EMFL) and Würzburg-Dresden Cluster of Excellence ct.qmat, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
- Present Address: Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - J. Wosnitza
- Dresden High Magnetic Field Laboratory (HLD-EMFL) and Würzburg-Dresden Cluster of Excellence ct.qmat, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
- Institut für Festkörper- und Materialphysik, TU Dresden, 01062 Dresden, Germany
| | - D. Hirai
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 Japan
| | - Z. Hiroi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 Japan
| | - M. Gen
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 Japan
| | - Y. Kohama
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 Japan
| | - A. Matsuo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 Japan
| | - Y. H. Matsuda
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 Japan
| | - K. Kindo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 Japan
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2
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Choi Y, Lee S, Lee JH, Lee S, Seong MJ, Choi KY. Bosonic spinons in anisotropic triangular antiferromagnets. Nat Commun 2021; 12:6453. [PMID: 34753923 DOI: 10.1038/s41467-021-26716-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 10/18/2021] [Indexed: 12/03/2022] Open
Abstract
Anisotropic triangular antiferromagnets can host two primary spin excitations, namely, spinons and triplons. Here, we utilize polarization-resolved Raman spectroscopy to assess the statistics and dynamics of spinons in Ca3ReO5Cl2. We observe a magnetic Raman continuum consisting of one- and two-pair spinon-antispinon excitations as well as triplon excitations. The twofold rotational symmetry of the spinon and triplon excitations are distinct from magnons. The strong thermal evolution of spinon scattering is compatible with the bosonic spinon scenario. The quasilinear spinon hardening with decreasing temperature is envisaged as the ordering of one-dimensional topological defects. This discovery will enable a fundamental understanding of novel phenomena induced by lowering spatial dimensionality in quantum spin systems. Spinons are quasisparticles that can appear in anisotropic triangular lattices, however, probing the statistics and dynamics of such excitations is experimentally challenging. Here, Choi et al present Raman spectroscopy measurements of anisotropic triangular lattices, showing a bosonic evolution of the spinon scattering.
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Fumega AO, Wong D, Schulz C, Rodríguez F, Blanco-Canosa S. Spectroscopy of the frustrated quantum antiferromagnet Cs 2CuCl 4. J Phys Condens Matter 2021; 33:495603. [PMID: 34517361 DOI: 10.1088/1361-648x/ac2648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 09/13/2021] [Indexed: 06/13/2023]
Abstract
We investigate the electronic structure of Cs2CuCl4, a material discussed in the framework of a frustrated quantum antiferromagnet, by means of resonant inelastic x-ray scattering (RIXS) and density functional theory (DFT). From the non-dispersive highly localizedddexcitations, we resolve the crystal field splitting of the Cu2+ions in a strongly distorted tetrahedral coordination. This allows us to model the RIXS spectrum within the crystal field theory (CFT), assign theddorbital excitations and retrieve experimentally the values of the crystal field splitting parametersDq,DsandDτ. The electronic structure obtainedab-initioagrees with the RIXS spectrum and modelled by CFT, highlighting the potential of combined spectroscopic, cluster and DFT calculations to determine the electronic ground state of complex materials.
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Affiliation(s)
- Adolfo O Fumega
- Departamento de Física Aplicada, Universidade de Santiago de Compostela, E-15782 Campus Sur s/n, Santiago de Compostela, Spain
- Instituto de Investigacións Tecnolóxicas, Universidade de Santiago de Compostela, E-15782 Campus Sur s/n, Santiago de Compostela, Spain
| | - D Wong
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - C Schulz
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - F Rodríguez
- MALTA TEAM, DCITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander, Spain
| | - S Blanco-Canosa
- Donostia International Physics Center (DIPC), San Sebastián, Spain
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
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4
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Lin G, Jeong J, Kim C, Wang Y, Huang Q, Masuda T, Asai S, Itoh S, Günther G, Russina M, Lu Z, Sheng J, Wang L, Wang J, Wang G, Ren Q, Xi C, Tong W, Ling L, Liu Z, Wu L, Mei J, Qu Z, Zhou H, Wang X, Park JG, Wan Y, Ma J. Field-induced quantum spin disordered state in spin-1/2 honeycomb magnet Na 2Co 2TeO 6. Nat Commun 2021; 12:5559. [PMID: 34548484 DOI: 10.1038/s41467-021-25567-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 08/18/2021] [Indexed: 11/08/2022] Open
Abstract
Spin-orbit coupled honeycomb magnets with the Kitaev interaction have received a lot of attention due to their potential of hosting exotic quantum states including quantum spin liquids. Thus far, the most studied Kitaev systems are 4d/5d-based honeycomb magnets. Recent theoretical studies predicted that 3d-based honeycomb magnets, including Na2Co2TeO6 (NCTO), could also be a potential Kitaev system. Here, we have used a combination of heat capacity, magnetization, electron spin resonance measurements alongside inelastic neutron scattering (INS) to study NCTO's quantum magnetism, and we have found a field-induced spin disordered state in an applied magnetic field range of 7.5 T < B (⊥ b-axis) < 10.5 T. The INS spectra were also simulated to tentatively extract the exchange interactions. As a 3d-magnet with a field-induced disordered state on an effective spin-1/2 honeycomb lattice, NCTO expands the Kitaev model to 3d compounds, promoting further interests on the spin-orbital effect in quantum magnets.
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Lim AR. Structures, local symmetries, and paramagnetic effects in Cs2Zn1-Cu Cl4 (y = 0, 0.3, 0.5, 0.7, and 1) mixed crystals by solid-state NMR. J Mol Struct 2021; 1228:129456. [DOI: 10.1016/j.molstruc.2020.129456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Abstract
We report the synthesis, crystal structure, and magnetic properties of the two new quantum antiferromagnets A3ReO5Cl2 (A = Sr, Ba). The crystal structure is isostructural with the mineral pinalite Pb3WO5Cl2, in which the Re6+ ion is square pyramidally coordinated by five oxide atoms and forms an anisotropic triangular lattice (ATL) made of S = 1/2 spins. The magnetic interactions J and J' in the ATL are estimated from magnetic susceptibilities to be 19.5 (44.9) and 9.2 (19.3) K, respectively, with J'/J = 0.47 (0.43) for A = Ba (Sr). For each compound, the heat capacity at low temperatures shows a large T-linear component with no signature of long-range magnetic order above 2 K, which suggests a gapless spin liquid state of one-dimensional character of the J chains in spite of the significantly large J' couplings. This is a consequence of one-dimensionalization by geometrical frustration in the ATL magnet; a similar phenomenon has been observed in two compounds with slightly smaller J'/J values: Cs2CuCl4 (J'/J = 0.3) and the related compound Ca3ReO5Cl2 (0.32). Our findings demonstrate that 5d mixed-anion compounds provide a unique opportunity to explore novel quantum magnetism.
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Affiliation(s)
- Daigorou Hirai
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Takeshi Yajima
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Kazuhiro Nawa
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Mitsuaki Kawamura
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Zenji Hiroi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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Ponomaryov AN, Zviagina L, Wosnitza J, Lampen-Kelley P, Banerjee A, Yan JQ, Bridges CA, Mandrus DG, Nagler SE, Zvyagin SA. Nature of Magnetic Excitations in the High-Field Phase of α-RuCl_{3}. Phys Rev Lett 2020; 125:037202. [PMID: 32745422 DOI: 10.1103/physrevlett.125.037202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 06/17/2020] [Accepted: 06/19/2020] [Indexed: 06/11/2023]
Abstract
We present comprehensive electron spin resonance (ESR) studies of in-plane oriented single crystals of α-RuCl_{3}, a quasi-two-dimensional material with honeycomb structure, focusing on its high-field spin dynamics. The measurements were performed in magnetic fields up to 16 T, applied along the [110] and [100] directions. Several ESR modes were detected. Combining our findings with recent inelastic neutron- and Raman-scattering data, we identified most of the observed excitations. Most importantly, we show that the low-temperature ESR response beyond the boundary of the magnetically ordered region is dominated by single- and two-particle processes with magnons as elementary excitations. The peculiarities of the excitation spectrum in the vicinity of the critical field are discussed.
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Affiliation(s)
- A N Ponomaryov
- Dresden High Magnetic Field Laboratory (HLD-EMFL) and Würzburg-Dresden Cluster of Excellence ct.qmat, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - L Zviagina
- Dresden High Magnetic Field Laboratory (HLD-EMFL) and Würzburg-Dresden Cluster of Excellence ct.qmat, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - J Wosnitza
- Dresden High Magnetic Field Laboratory (HLD-EMFL) and Würzburg-Dresden Cluster of Excellence ct.qmat, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
- Institut für Festkörper- und Materialphysik, TU Dresden, 01062 Dresden, Germany
| | - P Lampen-Kelley
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37821, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37821, USA
| | - A Banerjee
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J-Q Yan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37821, USA
| | - C A Bridges
- Chemical Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37821, USA
| | - D G Mandrus
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37821, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37821, USA
| | - S E Nagler
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - S A Zvyagin
- Dresden High Magnetic Field Laboratory (HLD-EMFL) and Würzburg-Dresden Cluster of Excellence ct.qmat, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
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Xie A, Yin X, Tang CS, Fauzi AD, Chi X, Diao C, Sahdan MF, Birowosuto MD, Dang C, Rusydi A, Wee ATS. Electronic Modulation in Site-Selective Occupation of Quasi-2D Triangular-Lattice Cs 2CuCl 4-xBr x Perovskite Probed by Surface-Sensitive Characterization. ACS Appl Mater Interfaces 2020; 12:4114-4122. [PMID: 31927903 DOI: 10.1021/acsami.9b19517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A controllable electronic manipulation in a frustrated magnetic system such as solution-based two-dimensional (2D) all-inorganic perovskites offers a possible route for their integrations with electronic and magnetic devices for their advanced applications. Here, we perform element-specific investigations of an emergent class of quasi-2D all-inorganic perovskites Cs2CuCl4-xBrx with (0 ≤ x ≤ 4) using a combination of synchrotron-radiation photoelectron techniques. Surface- and element-sensitive X-ray absorption spectroscopy spectra of Cu L2,3 edges indicate strong electronic transition that is largely influenced by their halogen content at room temperature. This implies that site-selective occupation largely dominates the electronic transition across the unoccupied states of these series since chlorine atoms possess a stronger electronegative character than bromine atoms. Moreover, the implication of halogen site is reflected in the valence band of Cl-rich copper perovskite in which the valence band edge is closer to Fermi energy (EF) than that of the Br-rich compound. Furthermore, X-ray magnetic circular dichroism spectra of mixed ratio and Br-rich compounds exhibit antiferromagnetism at room temperature. These site-specific magnetic-spectroscopic results are corroborated by density functional theory calculations. The strong electronic modulation and the local magnetic spectroscopy results in these solution-based and low-temperature-growth materials will pave the way toward energy- and cost-efficient perovskite devices.
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Affiliation(s)
- Aozhen Xie
- CINTRA UMI CNRS/NTU/THALES , Singapore 637553 , Singapore
- School of Electrical and Electronic Engineering , Nanyang Technological University , Singapore 639798 , Singapore
- Energy Research Institute@NTU (ERI@N) , Nanyang Technological University , Singapore 637553 , Singapore
| | - Xinmao Yin
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- Singapore Synchrotron Light Source (SSLS) , National University of Singapore , 5 Research Link , Singapore 117603 , Singapore
| | - Chi Sin Tang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- Singapore Synchrotron Light Source (SSLS) , National University of Singapore , 5 Research Link , Singapore 117603 , Singapore
- NUS Graduate School for Integrative Sciences and Engineering , National University of Singapore , Singapore 117456 , Singapore
| | - Angga Dito Fauzi
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- Singapore Synchrotron Light Source (SSLS) , National University of Singapore , 5 Research Link , Singapore 117603 , Singapore
| | - Xiao Chi
- Singapore Synchrotron Light Source (SSLS) , National University of Singapore , 5 Research Link , Singapore 117603 , Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , 6 Science Drive 2 , Singapore 117546 , Singapore
| | - Caozheng Diao
- Singapore Synchrotron Light Source (SSLS) , National University of Singapore , 5 Research Link , Singapore 117603 , Singapore
| | - Muhammad Fauzi Sahdan
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
| | - Muhammad Danang Birowosuto
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- Energy Research Institute@NTU (ERI@N) , Nanyang Technological University , Singapore 637553 , Singapore
| | - Cuong Dang
- CINTRA UMI CNRS/NTU/THALES , Singapore 637553 , Singapore
- School of Electrical and Electronic Engineering , Nanyang Technological University , Singapore 639798 , Singapore
- Energy Research Institute@NTU (ERI@N) , Nanyang Technological University , Singapore 637553 , Singapore
| | - Andrivo Rusydi
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- Singapore Synchrotron Light Source (SSLS) , National University of Singapore , 5 Research Link , Singapore 117603 , Singapore
- NUS Graduate School for Integrative Sciences and Engineering , National University of Singapore , Singapore 117456 , Singapore
- NUSNNI-NanoCore , National University of Singapore , Singapore 117411 , Singapore
| | - Andrew Thye Shen Wee
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , 6 Science Drive 2 , Singapore 117546 , Singapore
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Abstract
Quantum spin liquids are prime examples of strongly entangled phases of matter with unconventional exotic excitations. Here, strong quantum fluctuations prohibit the freezing of the spin system. On the other hand, frustrated magnets, the proper platforms to search for the quantum spin liquid candidates, still show a magnetic ground state in most of the cases. Pressure is an effective tuning parameter of structural properties and electronic correlations. Nevertheless, the ability to influence the magnetic phases should not be forgotten. We review experimental progress in the field of pressure-tuned magnetic interactions in candidate systems. Elaborating on the possibility of tuned quantum phase transitions, we further show that chemical or external pressure is a suitable parameter in these exotic states of matter.
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Tutsch U, Tsyplyatyev O, Kuhnt M, Postulka L, Wolf B, Cong PT, Ritter F, Krellner C, Aßmus W, Schmidt B, Thalmeier P, Kopietz P, Lang M. Specific Heat Study of 1D and 2D Excitations in the Layered Frustrated Quantum Antiferromagnets Cs_{2}CuCl_{4-x}Br_{x}. Phys Rev Lett 2019; 123:147202. [PMID: 31702204 DOI: 10.1103/physrevlett.123.147202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 05/30/2019] [Indexed: 06/10/2023]
Abstract
We report an experimental and theoretical study of the low-temperature specific heat C and magnetic susceptibility χ of the layered anisotropic triangular-lattice spin-1/2 Heisenberg antiferromagnets Cs_{2}CuCl_{4-x}Br_{x} with x=0, 1, 2, and 4. We find that the ratio J^{'}/J of the exchange couplings ranges from 0.32 to ≈0.78, implying a change (crossover or quantum phase transition) in the materials' magnetic properties from one-dimensional (1D) behavior for J^{'}/J<0.6 to two-dimensional (2D) behavior for J^{'}/J≈0.78. For J^{'}/J<0.6, realized for x=0, 1, and 4, we find a magnetic contribution to the low-temperature specific heat, C_{m}∝T, consistent with spinon excitations in 1D spin-1/2 Heisenberg antiferromagnets. Remarkably, for x=2, where J^{'}/J≈0.78 implies a 2D magnetic character, we also observe C_{m}∝T. This finding, which contrasts the prediction of C_{m}∝T^{2} made by standard spin-wave theories, shows that Fermi-like statistics also plays a significant role for the magnetic excitations in spin-1/2 frustrated 2D antiferromagnets.
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Affiliation(s)
- U Tutsch
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - O Tsyplyatyev
- Institut für Theoretische Physik, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - M Kuhnt
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - L Postulka
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - B Wolf
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - P T Cong
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - F Ritter
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - C Krellner
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - W Aßmus
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - B Schmidt
- Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany
| | - P Thalmeier
- Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany
| | - P Kopietz
- Institut für Theoretische Physik, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - M Lang
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
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Liu CB, He ZZ, Wang SL, Yang M, Liu Y, Liu YJ, Chen R, Zhu HP, Dong C, Ke JZ, Ouyang ZW, Xia ZC, Wang JF. Field-induced magnetic transitions and strong anisotropy in α-CoV 2O 6 single crystal. J Phys Condens Matter 2019; 31:375802. [PMID: 31163414 DOI: 10.1088/1361-648x/ab26fe] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The Ising-like antiferromagnet α-CoV2O6 has received considerable interests because of stabilized 1/3 magnetization plateau around 5 K under magnetic field applied along magnetic easy c-axis. In this work, this magnetization plateau was studied by varying temperature or rotating magnetic field. As temperature decreased, this stabilized plateau collapsed, and additional magnetic transitions were observed. As a result, a rich magnetic phase diagram was constructed and extended to temperature lower than previously reported. When magnetic field moved from the c to b (or a) axis, the magnetization plateau developed with field directions and vanished finally when the field was restricted in the ab plane. An impressive observation is that this 1/3-plateau can be stabilized and remain robust even when magnetic field deviated from the c axis, accompanied by the evolutions of the magnetic moments and the critical transition fields. We suppose that the origins of these temperature and angular dependences of the 1/3 magnetization plateau are related to strong spin-orbital coupling. Indeed, electron spin resonance (ESR) measurement gives large Landé factor of 8.9, evidencing that there exists strong spin-orbital coupling.
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Affiliation(s)
- C B Liu
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China. Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
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12
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Zvyagin SA, Graf D, Sakurai T, Kimura S, Nojiri H, Wosnitza J, Ohta H, Ono T, Tanaka H. Pressure-tuning the quantum spin Hamiltonian of the triangular lattice antiferromagnet Cs 2CuCl 4. Nat Commun 2019; 10:1064. [PMID: 30842420 PMCID: PMC6403288 DOI: 10.1038/s41467-019-09071-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 02/13/2019] [Indexed: 11/23/2022] Open
Abstract
Quantum triangular-lattice antiferromagnets are important prototype systems to investigate numerous phenomena of the geometrical frustration in condensed matter. Apart from highly unusual magnetic properties, they possess a rich phase diagram (ranging from an unfrustrated square lattice to a quantum spin liquid), yet to be confirmed experimentally. One major obstacle in this area of research is the lack of materials with appropriate (ideally tuned) magnetic parameters. Using Cs2CuCl4 as a model system, we demonstrate an alternative approach, where, instead of the chemical composition, the spin Hamiltonian is altered by hydrostatic pressure. The approach combines high-pressure electron spin resonance and r.f. susceptibility measurements, allowing us not only to quasi-continuously tune the exchange parameters, but also to accurately monitor them. Our experiments indicate a substantial increase of the exchange coupling ratio from 0.3 to 0.42 at a pressure of 1.8 GPa, revealing a number of emergent field-induced phases. Theoretical studies of quantum magnetism typically assume idealised lattices with freely tunable parameters, which are difficult to realise experimentally. Zvyagin et al. perform challenging measurements at high pressures to tune and to accurately monitor the exchange parameters of a triangular lattice antiferromagnet.
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Affiliation(s)
- S A Zvyagin
- Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, 01328, Dresden, Germany.
| | - D Graf
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - T Sakurai
- Research Facility Center for Science and Technology, Kobe University, Kobe, 657-8501, Japan
| | - S Kimura
- Institute for Materials Research, Tohoku University, Sendai, 980-8578, Japan
| | - H Nojiri
- Institute for Materials Research, Tohoku University, Sendai, 980-8578, Japan
| | - J Wosnitza
- Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, 01328, Dresden, Germany.,Institut für Festkörper- und Materialphysik, TU Dresden, 01062, Dresden, Germany
| | - H Ohta
- Molecular Photoscience Research Center, Kobe University, Kobe, 657-8501, Japan
| | - T Ono
- Department of Physical Science, Osaka Prefecture University, Osaka, 599-8531, Japan
| | - H Tanaka
- Department of Physics, Tokyo Institute of Technology, Tokyo, 152-8551, Japan
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13
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Little A, Wu L, Lampen-Kelley P, Banerjee A, Patankar S, Rees D, Bridges CA, Yan JQ, Mandrus D, Nagler SE, Orenstein J. Antiferromagnetic Resonance and Terahertz Continuum in α-RuCl_{3}. Phys Rev Lett 2017; 119:227201. [PMID: 29286790 DOI: 10.1103/physrevlett.119.227201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Indexed: 06/07/2023]
Abstract
We report measurements of optical absorption in the zigzag antiferromagnet α-RuCl_{3} as a function of temperature T, magnetic field B, and photon energy ℏω in the range ∼0.3-8.3 meV, using time-domain terahertz spectroscopy. Polarized measurements show that threefold rotational symmetry is broken in the honeycomb plane from 2 to 300 K. We find a sharp absorption peak at 2.56 meV upon cooling below the Néel temperature of 7 K at B=0 that we identify as the magnetic-dipole excitation of a zero-wave-vector magnon, or antiferromagnetic resonance (AFMR). With the application of B, the AFMR broadens and shifts to a lower frequency as long-range magnetic order is lost in a manner consistent with transitioning to a spin-disordered phase. From a direct, internally calibrated measurement of the AFMR spectral weight, we place an upper bound on the contribution to the dc susceptibility from a magnetic excitation continuum.
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Affiliation(s)
- A Little
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Liang Wu
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - P Lampen-Kelley
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - A Banerjee
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - S Patankar
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - D Rees
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, 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
| | - D Mandrus
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, 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
| | - J Orenstein
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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Wosnitza J, Zvyagin SA, Zherlitsyn S. Frustrated magnets in high magnetic fields-selected examples. Rep Prog Phys 2016; 79:074504. [PMID: 27310818 DOI: 10.1088/0034-4885/79/7/074504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
An indispensable parameter to study strongly correlated electron systems is the magnetic field. Application of high magnetic fields allows the investigation, modification and control of different states of matter. Specifically for magnetic materials experimental tools applied in such fields are essential for understanding their fundamental properties. Here, we focus on selected high-field studies of frustrated magnetic materials that have been shown to host a broad range of fascinating new and exotic phases. We will give brief insights into the influence of geometrical frustration on the critical behavior of triangular-lattice antiferromagnets, the accurate determination of exchange constants in the high-field saturated state by use of electron spin resonance measurements, and the coupling of magnetic degrees of freedom to the lattice evidenced by ultrasound experiments. The latter technique as well allowed new, partially metastable phases in strong magnetic fields to be revealed.
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Affiliation(s)
- J Wosnitza
- Hochfeld-Magnetlabor Dresden (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, D-01314 Dresden, Germany. Institut für Festkörperphysik, TU Dresden, D-01062 Dresden, Germany
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15
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Abstract
We review ground states and excitations of a quantum antiferromagnet on triangular and other frustrated lattices. We pay special attention to the combined effects of magnetic field h, spatial anisotropy R and spin magnitude S. The focus of the review is on the novel collinear spin density wave and spin nematic states, which are characterized by fully gapped transverse spin excitations with S(z) = ± 1. We discuss extensively the R - h phase diagram of the antiferromagnet, both in the large-S semiclassical limit and the quantum S = 1/2 limit. When possible, we point out connections with experimental findings.
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Affiliation(s)
- Oleg A Starykh
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112-0830, USA
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16
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Abstract
We consider 2D Heisenberg antiferromagnets on a triangular lattice with spatially anisotropic interactions in a high magnetic field close to the saturation. We show that this system possesses a rich phase diagram in a field or anisotropy plane due to competition between classical and quantum orders: an incommensurate noncoplanar spiral state, which is favored classically, and a commensurate coplanar state, which is stabilized by quantum fluctuations. We show that the transformation between these two states is highly nontrivial and involves two intermediate phases--the phase with coplanar incommensurate spin order and the one with noncoplanar double-Q spiral order. The transition between the two coplanar states is of commensurate-incommensurate type, not accompanied by softening of spin-wave excitations. We show that a different sequence of transitions holds in triangular antiferromagnets with exchange anisotropy, such as Ba(3)CoSb(2)O(9).
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Affiliation(s)
- Oleg A Starykh
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| | - Wen Jin
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| | - Andrey V Chubukov
- Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA
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