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Janas S, Lass J, Ţuţueanu AE, Haubro ML, Niedermayer C, Stuhr U, Xu G, Prabhakaran D, Deen PP, Holm-Dahlin S, Lefmann K. Classical Spin Liquid or Extended Critical Range in h-YMnO_{3}? PHYSICAL REVIEW LETTERS 2021; 126:107203. [PMID: 33784157 DOI: 10.1103/physrevlett.126.107203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 01/13/2021] [Indexed: 06/12/2023]
Abstract
Neutron spectroscopy on the classical triangular-lattice frustrated antiferromagnet h-YMnO_{3} reveals diffuse, gapless magnetic excitations present both far below and above the ordering temperature. The correlation length of the excitations increases as the temperature approaches zero, bearing a strong resemblance to critical scattering. We model the dynamics in the ordered and correlated disordered phase as critical spin correlations in a two-dimensional magnetic state. We propose that our findings may provide a general framework to understand features often attributed to classical spin liquids.
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Affiliation(s)
- Sofie Janas
- Nanoscience Center, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen Ø, Denmark
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Jakob Lass
- Nanoscience Center, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen Ø, Denmark
- Laboratory for Neutron Scattering, Paul Scherrer Institute (PSI), 5232 Villigen, Switzerland
| | - Ana-Elena Ţuţueanu
- Nanoscience Center, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen Ø, Denmark
- Institut Laue-Langevin (ILL), Grenoble Cedex 9 38042, France
| | - Morten L Haubro
- Nanoscience Center, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Christof Niedermayer
- Laboratory for Neutron Scattering, Paul Scherrer Institute (PSI), 5232 Villigen, Switzerland
| | - Uwe Stuhr
- Laboratory for Neutron Scattering, Paul Scherrer Institute (PSI), 5232 Villigen, Switzerland
| | - Guangyong Xu
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Dharmalingam Prabhakaran
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - Pascale P Deen
- Nanoscience Center, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen Ø, Denmark
- European Spallation Source ESS ERIC, Box 176, SE-221 00 Lund, Sweden
| | - Sonja Holm-Dahlin
- Nanoscience Center, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen Ø, Denmark
- ISIS Facility Rutherford Appleton Laboratory Chilton, Didcot, OX 11 OQX, United Kingdom
| | - Kim Lefmann
- Nanoscience Center, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen Ø, Denmark
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Huddart BM, Birch MT, Pratt FL, Blundell SJ, Porter DG, Clark SJ, Wu W, Julian SR, Hatton PD, Lancaster T. Local magnetism, magnetic order and spin freezing in the 'nonmetallic metal' FeCrAs. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:285803. [PMID: 30933932 DOI: 10.1088/1361-648x/ab151f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We present the results of x-ray scattering and muon-spin relaxation ([Formula: see text]SR) measurements on the iron-pnictide compound FeCrAs. Polarized non-resonant magnetic x-ray scattering results reveal the 120° periodicity expected from the suggested three-fold symmetric, non-collinear antiferromagnetic structure. [Formula: see text]SR measurements indicate a magnetically ordered phase throughout the bulk of the material below [Formula: see text] K. There are signs of fluctuating magnetism in a narrow range of temperatures above [Formula: see text] involving low-energy excitations, while at temperatures well below [Formula: see text] behaviour characteristic of freezing of dynamics is observed, likely reflecting the effect of disorder in our polycrystalline sample. Using density functional theory we propose a distinct muon stopping site in this compound and assess the degree of distortion induced by the implanted muon.
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Affiliation(s)
- B M Huddart
- Centre for Materials Physics, Durham University, Durham DH1 3LE, United Kingdom
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The Magnetic Phase Transition and Universality Class of h-YMnO3 and h-(Y0.98Eu0.02)MnO3 Under Zero and Applied Pressure. QUANTUM BEAM SCIENCE 2018. [DOI: 10.3390/qubs2030016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We investigated the antiferromagnetic phase transition in the frustrated and multiferroic hexagonal manganites h-YMnO 3 (YMO) and h-(Y 0.98 Eu 0.02 )MnO 3 (YEMO). Elastic neutron scattering was used to study, in detail, the phase transition in YMO and YEMO under zero pressure and in YMO under a hydrostatic pressure of 1.5 GPa. Under conditions of zero pressure, we found critical temperatures of T N = 71.3 ( 1 ) K and 72.11 ( 5 ) K and the critical exponent 0.22 ( 2 ) and β = 0.206 ( 3 ) , for YMO and YEMO, respectively. This is in agreement with earlier work by Roessli et al. Under an applied hydrostatic pressure of 1.5 GPa, the ordering temperature increased to T N = 75.2 ( 5 ) K, in agreement with earlier reports, while β was unchanged. Inelastic neutron scattering was used to determine the size of the anisotropy spin wave gap close to the phase transition. From spin wave theory, the gap is expected to close with a critical exponent, β ′ , identical to the order parameter β . Our results indicate that the gap in YEMO indeed closes at T N = 72.4 ( 3 ) K with β ′ = 0.24 ( 2 ) , while the in-pressure gap in YMO closes at 75.2(5) K with an exponent of β ′ = 0.19 ( 3 ) . In addition, the low temperature anisotropy gap was found to have a slightly higher absolute value under pressure. The consistent values obtained for β in the two systems support the likelihood of a new universality class for triangular, frustrated antiferromagnets.
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Oh J, Le MD, Nahm HH, Sim H, Jeong J, Perring TG, Woo H, Nakajima K, Ohira-Kawamura S, Yamani Z, Yoshida Y, Eisaki H, Cheong SW, Chernyshev AL, Park JG. Spontaneous decays of magneto-elastic excitations in non-collinear antiferromagnet (Y,Lu)MnO 3. Nat Commun 2016; 7:13146. [PMID: 27759004 PMCID: PMC5075801 DOI: 10.1038/ncomms13146] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 09/08/2016] [Indexed: 11/09/2022] Open
Abstract
Magnons and phonons are fundamental quasiparticles in a solid and can be coupled together to form a hybrid quasi-particle. However, detailed experimental studies on the underlying Hamiltonian of this particle are rare for actual materials. Moreover, the anharmonicity of such magnetoelastic excitations remains largely unexplored, although it is essential for a proper understanding of their diverse thermodynamic behaviour and intrinsic zero-temperature decay. Here we show that in non-collinear antiferromagnets, a strong magnon–phonon coupling can significantly enhance the anharmonicity, resulting in the creation of magnetoelastic excitations and their spontaneous decay. By measuring the spin waves over the full Brillouin zone and carrying out anharmonic spin wave calculations using a Hamiltonian with an explicit magnon–phonon coupling, we have identified a hybrid magnetoelastic mode in (Y,Lu)MnO3 and quantified its decay rate and the exchange-striction coupling term required to produce it. The properties of magnetic, crystalline solids can be described in terms of quantum particles of spin-wave and lattice-vibration energy, known as magnons and phonons respectively. Here, the authors show that strong magnon-phonon coupling in a noncollinear antiferromagnet can create magnetoelastic excitations.
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Affiliation(s)
- Joosung Oh
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea.,Department of Physics and Astronomy, Seoul National University, Kwanak-Gu, Seoul 08826, Korea
| | - Manh Duc Le
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea.,Department of Physics and Astronomy, Seoul National University, Kwanak-Gu, Seoul 08826, Korea
| | - Ho-Hyun Nahm
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea.,Department of Physics and Astronomy, Seoul National University, Kwanak-Gu, Seoul 08826, Korea
| | - Hasung Sim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea.,Department of Physics and Astronomy, Seoul National University, Kwanak-Gu, Seoul 08826, Korea
| | - Jaehong Jeong
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea.,Department of Physics and Astronomy, Seoul National University, Kwanak-Gu, Seoul 08826, Korea
| | - T G Perring
- ISIS Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - Hyungje Woo
- ISIS Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, UK.,Department of Physics, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Kenji Nakajima
- Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Seiko Ohira-Kawamura
- Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Zahra Yamani
- Chalk River Laboratories, National Research Council, Chalk River, Ontario, Canada K0J 1J0
| | - Y Yoshida
- National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8565, Japan
| | - H Eisaki
- National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8565, Japan
| | - S-W Cheong
- Department of Physics and Astronomy, and Rutgers Center for Emergent Materials, Rutgers University, Piscataway, New Jersey 08854, USA
| | - A L Chernyshev
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Je-Geun Park
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea.,Department of Physics and Astronomy, Seoul National University, Kwanak-Gu, Seoul 08826, Korea
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