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Phonon thermal Hall effect in a metallic spin ice. Nat Commun 2022; 13:4604. [PMID: 35933516 PMCID: PMC9357082 DOI: 10.1038/s41467-022-32375-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Accepted: 07/26/2022] [Indexed: 11/09/2022] Open
Abstract
It has become common knowledge that phonons can generate thermal Hall effect in a wide variety of materials, although the underlying mechanism is still controversial. We study longitudinal κxx and transverse κxy thermal conductivity in Pr2Ir2O7, which is a metallic analog of spin ice. Despite the presence of mobile charge carriers, we find that both κxx and κxy are dominated by phonons. A T/H scaling of κxx unambiguously reveals that longitudinal heat current is substantially impeded by resonant scattering of phonons on paramagnetic spins. Upon cooling, the resonant scattering is strongly affected by a development of spin ice correlation and κxx deviates from the scaling in an anisotropic way with respect to field directions. Strikingly, a set of the κxx and κxy data clearly shows that κxy correlates with κxx in its response to magnetic field including a success of the T/H scaling and its failure at low temperature. This remarkable correlation provides solid evidence that an indispensable role is played by spin-phonon scattering not only for hindering the longitudinal heat conduction, but also for generating the transverse response. The thermal Hall effect, or a temperature gradient transverse to a heat current and a magnetic field, has been observed in many materials, but its mechanism is not fully understood. Uehara et al. demonstrate the dominant phonon contribution to both longitudinal and transverse thermal response in a metallic spin ice Pr2Ir2O7.
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2
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Pearce MJ, Götze K, Szabó A, Sikkenk TS, Lees MR, Boothroyd AT, Prabhakaran D, Castelnovo C, Goddard PA. Magnetic monopole density and antiferromagnetic domain control in spin-ice iridates. Nat Commun 2022; 13:444. [PMID: 35064100 PMCID: PMC8782874 DOI: 10.1038/s41467-022-27964-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 12/22/2021] [Indexed: 11/09/2022] Open
Abstract
Magnetically frustrated systems provide fertile ground for complex behaviour, including unconventional ground states with emergent symmetries, topological properties, and exotic excitations. A canonical example is the emergence of magnetic-charge-carrying quasiparticles in spin-ice compounds. Despite extensive work, a reliable experimental indicator of the density of these magnetic monopoles is yet to be found. Using measurements on single crystals of Ho2Ir2O7 combined with dipolar Monte Carlo simulations, we show that the isothermal magnetoresistance is highly sensitive to the monopole density. Moreover, we uncover an unexpected and strong coupling between the monopoles on the holmium sublattice and the antiferromagnetically ordered iridium ions. These results pave the way towards a quantitative experimental measure of monopole density and demonstrate the ability to control antiferromagnetic domain walls using a uniform external magnetic field, a key goal in the design of next-generation spintronic devices.
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Affiliation(s)
- M J Pearce
- Department of Physics, University of Warwick, Coventry, UK
- Department of Physics, University of Oxford, Clarendon Laboratory, Oxford, UK
| | - K Götze
- Department of Physics, University of Warwick, Coventry, UK
- Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany
| | - A Szabó
- Department of Physics, University of Oxford, Clarendon Laboratory, Oxford, UK
- T.C.M. Group, Cavendish Laboratory, J. J. Thomson Avenue, University of Cambridge, Cambridge, UK
- ISIS Facility, Rutherford Appleton Laboratory, Didcot, UK
| | - T S Sikkenk
- T.C.M. Group, Cavendish Laboratory, J. J. Thomson Avenue, University of Cambridge, Cambridge, UK
- Institute for Theoretical Physics and Center for Extreme Matter and Emergent Phenomena, Utrecht University, Utrecht, The Netherlands
| | - M R Lees
- Department of Physics, University of Warwick, Coventry, UK
| | - A T Boothroyd
- Department of Physics, University of Oxford, Clarendon Laboratory, Oxford, UK
| | - D Prabhakaran
- Department of Physics, University of Oxford, Clarendon Laboratory, Oxford, UK
| | - C Castelnovo
- T.C.M. Group, Cavendish Laboratory, J. J. Thomson Avenue, University of Cambridge, Cambridge, UK.
| | - P A Goddard
- Department of Physics, University of Warwick, Coventry, UK.
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Lee JH, Ma J, Hahn SE, Cao HB, Lee M, Hong T, Lee HJ, Yeom MS, Okamoto S, Zhou HD, Matsuda M, Fishman RS. Magnetic Frustration Driven by Itinerancy in Spinel CoV 2O 4. Sci Rep 2017; 7:17129. [PMID: 29215077 PMCID: PMC5719412 DOI: 10.1038/s41598-017-17160-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 11/13/2017] [Indexed: 11/12/2022] Open
Abstract
Localized spins and itinerant electrons rarely coexist in geometrically-frustrated spinel lattices. They exhibit a complex interplay between localized spins and itinerant electrons. In this paper, we study the origin of the unusual spin structure of the spinel CoV2O4, which stands at the crossover from insulating to itinerant behavior using the first principle calculation and neutron diffraction measurement. In contrast to the expected paramagnetism, localized spins supported by enhanced exchange couplings are frustrated by the effects of delocalized electrons. This frustration produces a non-collinear spin state even without orbital orderings and may be responsible for macroscopic spin-glass behavior. Competing phases can be uncovered by external perturbations such as pressure or magnetic field, which enhances the frustration.
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Affiliation(s)
- J H Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, 44919, Republic of Korea.
| | - J Ma
- Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China.,Key Laboratory of Artificial Structures and Quantum Control, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - S E Hahn
- Neutron Data Analysis and Visualization Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA.,Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - H B Cao
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - M Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, 44919, Republic of Korea
| | - Tao Hong
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - H-J Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, 44919, Republic of Korea
| | - M S Yeom
- Department of Applied Research and Network R&D, Center for Computational Science and Engineering, Division of National Supercomputing R&D, Korea Institute of Science and Technology Information (KISTI), 245 Daehak-ro, Daejeon, 34141, Republic of Korea.
| | - S Okamoto
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - H D Zhou
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee, 37996, USA
| | - M Matsuda
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - R S Fishman
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
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Wang Z, Barros K, Chern GW, Maslov DL, Batista CD. Resistivity Minimum in Highly Frustrated Itinerant Magnets. PHYSICAL REVIEW LETTERS 2016; 117:206601. [PMID: 27886479 DOI: 10.1103/physrevlett.117.206601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Indexed: 06/06/2023]
Abstract
We study the transport properties of frustrated itinerant magnets comprising localized classical moments, which interact via exchange with the conduction electrons. Strong frustration stabilizes a liquidlike spin state, which extends down to temperatures well below the effective Ruderman-Kittel-Kasuya-Yosida interaction scale. The crossover into this state is characterized by spin structure factor enhancement at wave vectors smaller than twice the Fermi wave vector magnitude. The corresponding enhancement of electron scattering generates a resistivity upturn at decreasing temperatures.
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Affiliation(s)
- Zhentao Wang
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Kipton Barros
- Theoretical Division, T-4 and CNLS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Gia-Wei Chern
- Department of Physics, University of Virginia, Charlottesville, Virginia 22904, USA
| | - Dmitrii L Maslov
- Department of Physics, University of Florida, Gainesville, Florida 32611, USA
| | - Cristian D Batista
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
- Theoretical Division, T-4 and CNLS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
- Quantum Condensed Matter Division and Shull-Wollan Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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Yoshitake J, Nasu J, Motome Y. Fractional Spin Fluctuations as a Precursor of Quantum Spin Liquids: Majorana Dynamical Mean-Field Study for the Kitaev Model. PHYSICAL REVIEW LETTERS 2016; 117:157203. [PMID: 27768327 DOI: 10.1103/physrevlett.117.157203] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Indexed: 06/06/2023]
Abstract
Experimental identification of quantum spin liquids remains a challenge, as the pristine nature is to be seen in asymptotically low temperatures. We here theoretically show that the precursor of quantum spin liquids appears in the spin dynamics in the paramagnetic state over a wide temperature range. Using the cluster dynamical mean-field theory and the continuous-time quantum Monte Carlo method, which are newly developed in the Majorana fermion representation, we calculate the dynamical spin structure factor, relaxation rate in nuclear magnetic resonance, and magnetic susceptibility for the honeycomb Kitaev model whose ground state is a canonical example of the quantum spin liquid. We find that dynamical spin correlations show peculiar temperature and frequency dependence even below the temperature where static correlations saturate. The results provide the experimentally accessible symptoms of the fluctuating fractionalized spins evincing the quantum spin liquids.
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Affiliation(s)
- Junki Yoshitake
- Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
| | - Joji Nasu
- Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
| | - Yukitoshi Motome
- Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
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Hwang K, Kim YB. Theory of Multifarious Quantum Phases and Large Anomalous Hall Effect in Pyrochlore Iridate Thin Films. Sci Rep 2016; 6:30017. [PMID: 27418293 PMCID: PMC4945933 DOI: 10.1038/srep30017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 06/27/2016] [Indexed: 11/11/2022] Open
Abstract
We theoretically investigate emergent quantum phases in the thin film geometries of the pyrochore iridates, where a number of exotic quantum ground states are proposed to occur in bulk materials as a result of the interplay between electron correlation and strong spin-orbit coupling. The fate of these bulk phases as well as novel quantum states that may arise only in the thin film platforms, are studied via a theoretical model that allows layer-dependent magnetic structures. It is found that the magnetic order develop in inhomogeneous fashions in the thin film geometries. This leads to a variety of magnetic metal phases with modulated magnetic ordering patterns across different layers. Both the bulk and boundary electronic states in these phases conspire to promote unusual electronic properties. In particular, such phases are akin to the Weyl semimetal phase in the bulk system and they would exhibit an unusually large anomalous Hall effect.
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Affiliation(s)
- Kyusung Hwang
- Department of Physics and Centre for Quantum Materials, University of Toronto, Toronto, Ontario M5S 1A7, Canada
| | - Yong Baek Kim
- Department of Physics and Centre for Quantum Materials, University of Toronto, Toronto, Ontario M5S 1A7, Canada
- Canadian Institute for Advanced Research/Quantum Materials Program, Toronto, Ontario M5G 1Z8, Canada
- School of Physics, Korea Institute for Advanced Study, Seoul 130-722, Korea
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Essafi K, Benton O, Jaubert L. A kagome map of spin liquids from XXZ to Dzyaloshinskii-Moriya ferromagnet. Nat Commun 2016; 7:10297. [PMID: 26796866 PMCID: PMC4735753 DOI: 10.1038/ncomms10297] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 11/26/2015] [Indexed: 11/21/2022] Open
Abstract
Despite its deceptive simplicity, few concepts have more fundamental implications than chirality, from the therapeutic activity of drugs to the fundamental forces of nature. In magnetic materials, chirality gives rise to unconventional phenomena such as the anomalous Hall effect and multiferroicity, taking an enhanced flavour in the so-called spin-liquid phases where magnetic disorder prevails. Kagome systems sit at the crossroad of these ideas. Motivated by the recent synthesis of rare-earth kagome materials and the progresses in optical-lattice experiments, we bring together an entire network of spin liquids with anisotropic and Dzyaloshinskii-Moriya interactions. This network revolves around the Ising antiferromagnet and ends on (ferromagnetic) chiral spin liquids with spontaneously broken time-reversal symmetry. As for the celebrated Heisenberg antiferromagnet, it now belongs to a triad of equivalently disordered phases. The present work provides a unifying theory of kagome spin liquids with time-reversal invariant nearest-neighbour Hamiltonians.
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Affiliation(s)
- Karim Essafi
- Okinawa Inst Sci & Technol, Onna, Okinawa 904 0495, Japan
| | - Owen Benton
- Okinawa Inst Sci & Technol, Onna, Okinawa 904 0495, Japan
| | - L.D.C. Jaubert
- Okinawa Inst Sci & Technol, Onna, Okinawa 904 0495, Japan
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Udagawa M, Moessner R. Anomalous Hall effect from frustration-tuned scalar chirality distribution in Pr2Ir2O7. PHYSICAL REVIEW LETTERS 2013; 111:036602. [PMID: 23909347 DOI: 10.1103/physrevlett.111.036602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Indexed: 06/02/2023]
Abstract
We study the anomalous Hall effect due to noncoplanar magnetism on a pyrochlore structure. We focus on the frustration-induced spatial inhomogeneity of different magnetic low-temperature regimes, between which one can efficiently tune using an external magnetic field. We incorporate nonmagnetic scattering on a phenomenological level so that we can distinguish between the effects of short-range correlations and short-range coherence. We obtain a Hall conductivity (σ(H)) as a function of field strength and direction which compares well to the experimental data of Pr(2)Ir(2)O(7). In particular, we show that the observed peak in σ(H) for H[parallel][111] signals the crossover from zero-field spin ice to kagome ice.
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Affiliation(s)
- M Udagawa
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
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Chern GW, Maiti S, Fernandes RM, Wölfle P. Electronic transport in the Coulomb phase of the pyrochlore spin ice. PHYSICAL REVIEW LETTERS 2013; 110:146602. [PMID: 25167019 DOI: 10.1103/physrevlett.110.146602] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Indexed: 06/03/2023]
Abstract
We investigate the transport properties of itinerant electrons interacting with a background of localized spins in a correlated paramagnetic phase of the pyrochlore lattice. We find a residual resistivity at zero temperature due to the scattering of electrons by the static dipolar spin-spin correlation that characterizes the metallic Coulomb phase. As temperature increases, thermally excited topological defects, also known as magnetic monopoles, reduce the spin correlation, hence suppressing electron scattering. Combined with the usual scattering processes in metals at higher temperatures, this mechanism yields a nonmonotonic resistivity, displaying a minimum at temperature scales associated with the magnetic monopole excitation energy. Our calculations agree quantitatively with resistivity measurements in Nd(2)Ir(2)O(7) and Pr(2)Ir(2)O(7), shedding light on the origin of the resistivity minimum observed in metallic spin-ice compounds.
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Affiliation(s)
- Gia-Wei Chern
- Theoretical Division, T-4 and CNLS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA and Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - Saurabh Maiti
- Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - Rafael M Fernandes
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Peter Wölfle
- Institute for Condensed Matter Theory and Institute for Nanotechnology, Karlsruhe Institute of Technology, D-76128 Karlsruhe, Germany
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Ishizuka H, Motome Y. Partial disorder in an Ising-spin Kondo lattice model on a triangular lattice. PHYSICAL REVIEW LETTERS 2012; 108:257205. [PMID: 23004651 DOI: 10.1103/physrevlett.108.257205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Indexed: 06/01/2023]
Abstract
A phase diagram of an Ising-spin Kondo lattice model on a triangular lattice near 1/3 filling is investigated by Monte Carlo simulation. We identify a partially disordered phase with the coexistence of magnetic order and paramagnetic moments, which was unstable in two-dimensional Ising models with localized spins only. The partial disorder emerges in the competing regime between a two-sublattice stripe phase and three-sublattice ferrimagnetic phase, at finite temperatures above an electronic phase separation. The peculiar magnetic structure accompanies a charge order and develops a gap in the electronic structure. The results manifest a crucial role of the nonperturbative interplay between spin and charge degrees of freedom in stabilizing the partial disorder.
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Affiliation(s)
- Hiroaki Ishizuka
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
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