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Schnack J, Schulenburg J, Honecker A, Richter J. Magnon Crystallization in the Kagome Lattice Antiferromagnet. PHYSICAL REVIEW LETTERS 2020; 125:117207. [PMID: 32975976 DOI: 10.1103/physrevlett.125.117207] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 08/10/2020] [Indexed: 06/11/2023]
Abstract
We present numerical evidence for the crystallization of magnons below the saturation field at nonzero temperatures for the highly frustrated spin-half kagome Heisenberg antiferromagnet. This phenomenon can be traced back to the existence of independent localized magnons or, equivalently, flatband multimagnon states. We present a loop-gas description of these localized magnons and a phase diagram of this transition, thus providing information for which magnetic fields and temperatures magnon crystallization can be observed experimentally. The emergence of a finite-temperature continuous transition to a magnon crystal is expected to be generic for spin models in dimension D>1 where flatband multimagnon ground states break translational symmetry.
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Affiliation(s)
- Jürgen Schnack
- Fakultät für Physik, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
| | - Jörg Schulenburg
- Universitätsrechenzentrum, Universität Magdeburg, D-39016 Magdeburg, Germany
| | - Andreas Honecker
- Laboratoire de Physique Théorique et Modélisation, CNRS UMR 8089, CY Cergy Paris Université, F-95302 Cergy-Pontoise Cedex, France
| | - Johannes Richter
- Institut für Physik, Universität Magdeburg, P.O. Box 4120, D-39016 Magdeburg, Germany
- Max-Planck-Institut für Physik Komplexer Systeme, Nöthnitzer Straße 38, D-01187 Dresden, Germany
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2
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Kamiya Y, Ge L, Hong T, Qiu Y, Quintero-Castro DL, Lu Z, Cao HB, Matsuda M, Choi ES, Batista CD, Mourigal M, Zhou HD, Ma J. The nature of spin excitations in the one-third magnetization plateau phase of Ba 3CoSb 2O 9. Nat Commun 2018; 9:2666. [PMID: 29991805 PMCID: PMC6039502 DOI: 10.1038/s41467-018-04914-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 05/21/2018] [Indexed: 11/25/2022] Open
Abstract
Magnetization plateaus in quantum magnets—where bosonic quasiparticles crystallize into emergent spin superlattices—are spectacular yet simple examples of collective quantum phenomena escaping classical description. While magnetization plateaus have been observed in a number of spin-1/2 antiferromagnets, the description of their magnetic excitations remains an open theoretical and experimental challenge. Here, we investigate the dynamical properties of the triangular-lattice spin-1/2 antiferromagnet Ba3CoSb2O9 in its one-third magnetization plateau phase using a combination of nonlinear spin-wave theory and neutron scattering measurements. The agreement between our theoretical treatment and the experimental data demonstrates that magnons behave semiclassically in the plateau in spite of the purely quantum origin of the underlying magnetic structure. This allows for a quantitative determination of Ba3CoSb2O9 exchange parameters. We discuss the implication of our results to the deviations from semiclassical behavior observed in zero-field spin dynamics of the same material and conclude they must have an intrinsic origin. Frustrated magnetic materials attract significant interest because their properties can become dominated by quantum fluctuations. Here the authors show that excitations in the plateau phase of a quantum magnet can be understood semiclassically even though the ground state involves strong quantum effects.
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Affiliation(s)
- Y Kamiya
- Condensed Matter Theory Laboratory, RIKEN, Wako, Saitama, 351-0198, Japan.
| | - L Ge
- School of Physics, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Tao Hong
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Y Qiu
- NIST Centre for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - D L Quintero-Castro
- Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109, Berlin, Germany
| | - Z Lu
- Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109, Berlin, Germany
| | - H B Cao
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - M Matsuda
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - E S Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - C D Batista
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA.,Neutron Scattering Division and Shull-Wollan Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - M Mourigal
- School of Physics, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - H D Zhou
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA.,Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA
| | - J Ma
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA. .,Key Laboratory of Artificial Structures and Quantum Control, Department of Physics and Astronomy, Shanghai Jiao Tong University, 200240, Shanghai, China. .,Collaborative Innovation Center of Advanced Microstructures, 210093, Nanjing, Jiangsu, China.
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3
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Ito S, Kurita N, Tanaka H, Ohira-Kawamura S, Nakajima K, Itoh S, Kuwahara K, Kakurai K. Structure of the magnetic excitations in the spin-1/2 triangular-lattice Heisenberg antiferromagnet Ba 3CoSb 2O 9. Nat Commun 2017; 8:235. [PMID: 28794443 PMCID: PMC5550445 DOI: 10.1038/s41467-017-00316-x] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 06/16/2017] [Indexed: 11/09/2022] Open
Abstract
A spin-1/2 triangular-lattice Heisenberg antiferromagnet (TLHAF) is a prototypical frustrated quantum magnet, which exhibits remarkable quantum many-body effects that arise from the synergy between spin frustration and quantum fluctuation. The ground-state properties of a spin-1/2 TLHAF are theoretically well understood. However, the theoretical consensus regarding the magnetic excitations is limited. The experimental study of the magnetic excitations in spin-1/2 TLHAFs has also been limited. Here we show the structure of magnetic excitations in the spin-1/2 TLHAF Ba3CoSb2O9 investigated by inelastic neutron scattering. Significantly different from theoretical expectations, the excitation spectrum has a three-stage energy structure. The lowest-energy first stage is composed of dispersion branches of single-magnon excitations. The second and third stages are dispersive continua accompanied by a columnar continuum extending above 10 meV, which is six times larger than the exchange interaction J = 1.67 meV. Our results indicate the shortcomings of the current theoretical framework. Two-dimensional frustrated magnets are heavily studied because theories predict that quantum effects may lead to the emergence of fractionalized excitations. Ito et al. use inelastic neutron scattering to show that the excitation spectrum of Ba3CoSb2O9 disagrees with current theoretical expectations.
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Affiliation(s)
- Saya Ito
- Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro-ku, Tokyo, 152-8551, Japan
| | - Nobuyuki Kurita
- Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro-ku, Tokyo, 152-8551, Japan
| | - Hidekazu Tanaka
- Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro-ku, Tokyo, 152-8551, Japan.
| | - Seiko Ohira-Kawamura
- Materials and Life Science Division, J-PARC Center, Tokai, Ibaraki, 319-1195, Japan
| | - Kenji Nakajima
- Materials and Life Science Division, J-PARC Center, Tokai, Ibaraki, 319-1195, Japan
| | - Shinichi Itoh
- Neutron Science Division, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki, 305-0801, Japan
| | - Keitaro Kuwahara
- Institute of Quantum Beam Science, Ibaraki University, Mito, 310-8512, Japan
| | - Kazuhisa Kakurai
- Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki, 319-1106, Japan
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Liu M, Zhang H, Huang X, Ma C, Dong S, Liu JM. Two-Step Antiferromagnetic Transitions and Ferroelectricity in Spin-1 Triangular-Lattice Antiferromagnetic Sr3NiTa2O9. Inorg Chem 2016; 55:2709-16. [PMID: 26934503 DOI: 10.1021/acs.inorgchem.5b02270] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
We report the low-temperature characterizations on structural, specific heat, magnetic, and ferroelectric behaviors of transition metal oxide compound Sr3NiTa2O9. It is suggested that Sr3NiTa2O9 is a spin-1 triangular lattice Heisenberg quantum antiferromagnet which may have weak easy-axis anisotropy. At zero magnetic field, a two-step transition sequence at T(N1) = 3.35 K and T(N2) = 2.74 K, respectively, is observed, corresponding to the up-up-down (uud) spin ordering and 120° spin ordering, respectively. The two transition points shift gradually with increasing magnetic field toward the low temperature, accompanying an evolution from the 120° spin structure (phase) to the normal oblique phases. Ferroelectricity in the 120° phase is clearly identified. The first-principles calculations confirm the 120° phase as the ground state whose ferroelectricity originates mainly from the electronic polarization.
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Affiliation(s)
- Meifeng Liu
- Laboratory of Solid State Microstructures and Innovative Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Huimin Zhang
- Department of Physics, Southeast University , Nanjing 211189, China
| | - Xin Huang
- Department of Physics, Southeast University , Nanjing 211189, China
| | - Chunyang Ma
- Laboratory of Solid State Microstructures and Innovative Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Shuai Dong
- Department of Physics, Southeast University , Nanjing 211189, China
| | - Jun-Ming Liu
- Laboratory of Solid State Microstructures and Innovative Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China.,Institute for Advanced Materials and Laboratory of Quantum Engineering and Materials, South China Normal University , Guangzhou 510006, China
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Yamamoto D, Marmorini G, Danshita I. Microscopic model calculations for the magnetization process of layered triangular-lattice quantum antiferromagnets. PHYSICAL REVIEW LETTERS 2015; 114:027201. [PMID: 25635561 DOI: 10.1103/physrevlett.114.027201] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Indexed: 06/04/2023]
Abstract
Magnetization processes of spin-1/2 layered triangular-lattice antiferromagnets (TLAFs) under a magnetic field H are studied by means of a numerical cluster mean-field method with a scaling scheme. We find that small antiferromagnetic couplings between the layers give rise to several types of extra quantum phase transitions among different high-field coplanar phases. Especially, a field-induced first-order transition is found to occur at H≈0.7H_{s}, where H_{s} is the saturation field, as another common quantum effect of ideal TLAFs in addition to the well-established one-third plateau. Our microscopic model calculation with appropriate parameters shows excellent agreement with experiments on Ba_{3}CoSb_{2}O_{9} [T. Susuki et al., Phys. Rev. Lett. 110, 267201 (2013)]. Given this fact, we suggest that the Co^{2+}-based compounds may allow for quantum simulations of intriguing properties of this simple frustrated model, such as quantum criticality and supersolid states.
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Affiliation(s)
- Daisuke Yamamoto
- Waseda Institute for Advanced Study, Waseda University, Tokyo 169-8050, Japan
| | - Giacomo Marmorini
- Condensed Matter Theory Laboratory, RIKEN, Saitama 351-0198, Japan and Research and Education Center for Natural Sciences, Keio University, Kanagawa 223-8521, Japan
| | - Ippei Danshita
- Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan and Computational Condensed Matter Physics Laboratory, RIKEN, Saitama 351-0198, Japan
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Yamamoto D, Marmorini G, Danshita I. Quantum phase diagram of the triangular-lattice XXZ model in a magnetic field. PHYSICAL REVIEW LETTERS 2014; 112:127203. [PMID: 24724677 DOI: 10.1103/physrevlett.112.127203] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Indexed: 06/03/2023]
Abstract
The triangular lattice of S=1/2 spins with XXZ anisotropy is a ubiquitous model for various frustrated systems in different contexts. We determine the quantum phase diagram of the model in the plane of the anisotropy parameter and the magnetic field by means of a large-size cluster mean-field method with a scaling scheme. We find that quantum fluctuations break up the nontrivial continuous degeneracy into two first-order phase transitions. In between the two transition boundaries, the degeneracy-lifting results in the emergence of a new coplanar phase not predicted in the classical counterpart of the model. We suggest that the quantum phase transition to the nonclassical coplanar state can be observed in triangular-lattice antiferromagnets with large easy-plane anisotropy or in the corresponding optical-lattice systems.
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Affiliation(s)
- Daisuke Yamamoto
- Condensed Matter Theory Laboratory, RIKEN, Saitama 351-0198, Japan
| | - Giacomo Marmorini
- Condensed Matter Theory Laboratory, RIKEN, Saitama 351-0198, Japan and Research and Education Center for Natural Sciences, Keio University, Kanagawa 223-8521, Japan
| | - Ippei Danshita
- Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan and Computational Condensed Matter Physics Laboratory, RIKEN, Saitama 351-0198, Japan
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Susuki T, Kurita N, Tanaka T, Nojiri H, Matsuo A, Kindo K, Tanaka H. Magnetization process and collective excitations in the S=1/2 triangular-lattice Heisenberg antiferromagnet Ba3CoSb2O9. PHYSICAL REVIEW LETTERS 2013; 110:267201. [PMID: 23848914 DOI: 10.1103/physrevlett.110.267201] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2013] [Indexed: 06/02/2023]
Abstract
We have performed high-field magnetization and electronic spin resonance (ESR) measurements on Ba3CoSb2O9 single crystals, which approximates the two-dimensional (2D) S=1/2 triangular-lattice Heisenberg antiferromagnet. For an applied magnetic field H parallel to the ab plane, the entire magnetization curve including the plateau at one-third of the saturation magnetization (Ms) is in excellent agreement with the results of theoretical calculations except a small step anomaly near (3/5)Ms, indicative of a theoretically undiscovered quantum phase transition. However, for H∥c, the magnetization curve exhibits a cusp near Ms/3 owing to the weak easy-plane anisotropy and the 2D quantum fluctuation. From a detailed analysis of the collective ESR modes observed in the ordered state, combined with the magnetization process, we have determined all the magnetic parameters including the interlayer and anisotropic exchange interactions.
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Affiliation(s)
- Takuya Susuki
- Department of Physics, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan
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Zhou HD, Xu C, Hallas AM, Silverstein HJ, Wiebe CR, Umegaki I, Yan JQ, Murphy TP, Park JH, Qiu Y, Copley JRD, Gardner JS, Takano Y. Successive phase transitions and extended spin-excitation continuum in the S=1/2 triangular-lattice antiferromagnet Ba3CoSb2O9. PHYSICAL REVIEW LETTERS 2012; 109:267206. [PMID: 23368612 DOI: 10.1103/physrevlett.109.267206] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Indexed: 06/01/2023]
Abstract
Using magnetic, thermal, and neutron measurements on single-crystal samples, we show that Ba3CoSb2O9 is a spin-1/2 triangular-lattice antiferromagnet with the c axis as the magnetic easy axis and two magnetic phase transitions bracketing an intermediate up-up-down phase in magnetic field applied along the c axis. A pronounced extensive neutron-scattering continuum above spin-wave excitations, observed below T(N), implies that the system is in close proximity to one of two spin-liquid states that have been predicted for a 2D triangular lattice.
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Affiliation(s)
- H D Zhou
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200, USA.
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9
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Banik S, Pal S, Prasad MD. Vibrational multi-reference coupled cluster theory in bosonic representation. J Chem Phys 2012; 137:114108. [DOI: 10.1063/1.4753422] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Shirata Y, Tanaka H, Matsuo A, Kindo K. Experimental realization of a spin-1/2 triangular-lattice Heisenberg antiferromagnet. PHYSICAL REVIEW LETTERS 2012; 108:057205. [PMID: 22400958 DOI: 10.1103/physrevlett.108.057205] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Indexed: 05/31/2023]
Abstract
We report the results of magnetization and specific heat measurements on Ba{3}CoSb{2}O{9}, in which the magnetic Co{2+} ion has a fictitious spin 1/2, and provide evidence that a spin-1/2 Heisenberg antiferromagnet on a regular triangular lattice is actually realized in Ba{3}CoSb{2}O{9}. We found that the entire magnetization curve including the one-third quantum magnetization plateau is in excellent quantitative agreement with the results of theoretical calculations. We also found that Ba{3}CoSb{2}O{9} undergoes a three-step transition within a narrow temperature range.
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Affiliation(s)
- Yutaka Shirata
- Department of Physics, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan
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Takano J, Tsunetsugu H, Zhitomirsky ME. Self-consistent spin wave analysis of the magnetization plateau in triangular antiferromagnet. ACTA ACUST UNITED AC 2011. [DOI: 10.1088/1742-6596/320/1/012011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Zinke R, Richter J, Drechsler SL. Spiral correlations in frustrated one-dimensional spin-1/2 Heisenberg J1-J2-J3 ferromagnets. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:446002. [PMID: 21403358 DOI: 10.1088/0953-8984/22/44/446002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We use the coupled cluster method for infinite chains complemented by exact diagonalization of finite periodic chains to discuss the influence of a third-neighbor exchange J(3) on the ground state of the spin-½ Heisenberg chain with ferromagnetic nearest-neighbor interaction J(1) and frustrating antiferromagnetic next-nearest-neighbor interaction J(2). A third-neighbor exchange J(3) might be relevant to describe the magnetic properties of the quasi-one-dimensional edge-shared cuprates, such as LiVCuO(4) or LiCu(2)O(2). In particular, we calculate the critical point J(2)(c) as a function of J(3), where the ferromagnetic ground state gives way for a ground state with incommensurate spiral correlations. For antiferromagnetic J(3) the ferro-spiral transition is always continuous and the critical values J(2)(c) of the classical and the quantum model coincide. On the other hand, for ferromagnetic J3 is < or approximately equal to -(0.01...0.02)|J1|. the critical value J(2)(c) of the quantum model is smaller than that of the classical model. Moreover, the transition becomes discontinuous, i.e. the model exhibits a quantum tricritical point. We also calculate the height of the jump of the spiral pitch angle at the discontinuous ferro-spiral transition.
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Affiliation(s)
- R Zinke
- Institut für Theoretische Physik, Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany
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