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Xiao TT, Ouyang ZW, Liu XC, Cao JJ, Wang ZX, Tong W. Angular dependence of spin-flop transition in triangular lattice antiferromagnet Cu 2(OH) 3Br. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:275804. [PMID: 35453130 DOI: 10.1088/1361-648x/ac69a0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 04/22/2022] [Indexed: 06/14/2023]
Abstract
We report angular dependence of spin-flop transition in triangular lattice antiferromagnet Cu2(OH)3Br by angle-dependent magnetization and ESR measurements. The results show that the antiferromagnetic easy magnetization axis is the diagonal direction (θ= 45°) of theac*plane, i.e., the orientation of Cu1 spins based on the magnetic structure (2020Phys. Rev. Lett.125037204), whereas the spin-flop axis is thebaxis. A phenomenological model is proposed to describe the angle-dependent spin-flop transitions. Based on this model, Cu1 spins are sensitive to external magnetic field, while Cu2 spins are robust against to the field, showing partial decoupling. The model is expected to be used in other uniaxial antiferromagnets with a more general easy axis and complex spin-flop transitions.
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Affiliation(s)
- T T Xiao
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - Z W Ouyang
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - X C Liu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - J J Cao
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - Z X Wang
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - W Tong
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
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Saniur Rahaman S, Sahoo S, Kumar M. Quantum phases and thermodynamics of a frustrated spin-1/2 ladder with alternate Ising-Heisenberg rung interactions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:265801. [PMID: 33857937 DOI: 10.1088/1361-648x/abf882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/15/2021] [Indexed: 06/12/2023]
Abstract
We study a frustrated two-leg spin ladder with alternate isotropic Heisenberg and Ising rung exchange interactions, whereas, interactions along legs and diagonals are Ising-type. All the interactions in the ladder are anti-ferromagnetic in nature and induce frustration in the system. This model shows four interesting quantum phases: (i) stripe rung ferromagnetic (SRFM), (ii) stripe rung ferromagnetic with edge singlet (SRFM-E), (iii) anisotropic antiferromagnetic (AAFM), and (iv) stripe leg ferromagnetic (SLFM) phase. We construct a quantum phase diagram for this model and show that in stripe rung ferromagnet (SRFM), the same type of sublattice spins (either isotropicS-type or discrete anisotropicσ-type spins) are aligned in the same direction. Whereas, in anisotropic antiferromagnetic phase, bothSandσ-type of spins are anti-ferromagnetically aligned with each other, two nearestSspins along the rung form an anisotropic singlet bond whereas two nearestσspins form an Ising bond. In large Heisenberg rung exchange interaction limit, spins on each leg are ferromagnetically aligned, but spins on different legs are anti-ferromagnetically aligned. The thermodynamic quantities like specific heatCv(T), magnetic susceptibilityχ(T) and thermal entropyS(T) are also calculated using the transfer matrix method for various phases. The magnetic gap in the SRFM and the SLFM can be noticed fromχ(T) andCv(T) curves.
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Affiliation(s)
- Sk Saniur Rahaman
- S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
| | - Shaon Sahoo
- Department of Physics, Indian Institute of Technology, Tirupati, India
| | - Manoranjan Kumar
- S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
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Tian D, Winter SM, Mailman A, Wong JWL, Yong W, Yamaguchi H, Jia Y, Tse JS, Desgreniers S, Secco RA, Julian SR, Jin C, Mito M, Ohishi Y, Oakley RT. The metallic state in neutral radical conductors: dimensionality, pressure and multiple orbital effects. J Am Chem Soc 2015; 137:14136-48. [PMID: 26513125 DOI: 10.1021/jacs.5b08254] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Pressure-induced changes in the solid-state structures and transport properties of three oxobenzene-bridged bisdithiazolyl radicals 2 (R = H, F, Ph) over the range 0-15 GPa are described. All three materials experience compression of their π-stacked architecture, be it (i) 1D ABABAB π-stack (R = Ph), (ii) quasi-1D slipped π-stack (R = H), or (iii) 2D brick-wall π-stack (R = F). While R = H undergoes two structural phase transitions, neither of R = F, Ph display any phase change. All three radicals order as spin-canted antiferromagnets, but spin-canted ordering is lost at pressures <1.5 GPa. At room temperature, their electrical conductivity increases rapidly with pressure, and the thermal activation energy for conduction Eact is eliminated at pressures ranging from ∼3 GPa for R = F to ∼12 GPa for R = Ph, heralding formation of a highly correlated (or bad) metallic state. For R = F, H the pressure-induced Mott insulator to metal conversion has been tracked by measurements of optical conductivity at ambient temperature and electrical resistivity at low temperature. For R = F compression to 6.2 GPa leads to a quasiquadratic temperature dependence of the resistivity over the range 5-300 K, consistent with formation of a 2D Fermi liquid state. DFT band structure calculations suggest that the ease of metallization of these radicals can be ascribed to their multiorbital character. Mixing and overlap of SOMO- and LUMO-based bands affords an increased kinetic energy stabilization of the metallic state relative to a single SOMO-based band system.
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Affiliation(s)
- Di Tian
- Department of Physics, University of Toronto , Toronto, Ontario M5S 1A7 Canada
| | - Stephen M Winter
- Department of Chemistry, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada
| | - Aaron Mailman
- Department of Chemistry, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada
| | - Joanne W L Wong
- Department of Chemistry, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada
| | - Wenjun Yong
- Department of Earth Sciences, University of Western Ontario , London, Ontario N6A 5B7, Canada
| | - Hiroshi Yamaguchi
- Faculty of Engineering, Kyushu Institute of Technology , Kitakyushu 804-8550, Japan
| | - Yating Jia
- Institute of Physics, Chinese Academy of Sciences , Beijing, 100080, China
| | - John S Tse
- Department of Physics, University of Saskatchewan , Saskatoon, Saskatchewan S7N 5E2, Canada
| | - Serge Desgreniers
- Department of Physics, University of Ottawa , Ottawa, Ontario K1N 6N5, Canada
| | - Richard A Secco
- Department of Earth Sciences, University of Western Ontario , London, Ontario N6A 5B7, Canada
| | - Stephen R Julian
- Department of Physics, University of Toronto , Toronto, Ontario M5S 1A7 Canada.,Canadian Institute for Advanced Research , Toronto, Ontario M5G 1Z8, Canada
| | - Changqing Jin
- Institute of Physics, Chinese Academy of Sciences , Beijing, 100080, China
| | - Masaki Mito
- Faculty of Engineering, Kyushu Institute of Technology , Kitakyushu 804-8550, Japan
| | - Yasuo Ohishi
- Materials Science Division, Japan Synchrotron Radiation Research Institute , SPring-8, Sayo, Hyogo 679-5198, Japan
| | - Richard T Oakley
- Department of Chemistry, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada
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