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Stock C, Rodriguez EE, Lee N, Demmel F, Fouquet P, Laver M, Niedermayer C, Su Y, Nemkovski K, Green MA, Rodriguez-Rivera JA, Kim JW, Zhang L, Cheong SW. Orphan Spins in the S=5/2 Antiferromagnet CaFe_{2}O_{4}. PHYSICAL REVIEW LETTERS 2017; 119:257204. [PMID: 29303328 DOI: 10.1103/physrevlett.119.257204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Indexed: 06/07/2023]
Abstract
CaFe_{2}O_{4} is an anisotropic S=5/2 antiferromagnet with two competing A (↑↑↓↓) and B (↑↓↑↓) magnetic order parameters separated by static antiphase boundaries at low temperatures. Neutron diffraction and bulk susceptibility measurements, show that the spins near these boundaries are weakly correlated and a carry an uncompensated ferromagnetic moment that can be tuned with a magnetic field. Spectroscopic measurements find these spins are bound with excitation energies less than the bulk magnetic spin waves and resemble the spectra from isolated spin clusters. Localized bound orphaned spins separate the two competing magnetic order parameters in CaFe_{2}O_{4}.
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Affiliation(s)
- C Stock
- School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
| | - E E Rodriguez
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
| | - N Lee
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
| | - F Demmel
- ISIS Facility, Rutherford Appleton Labs, Chilton, Didcot OX11 0QX, United Kingdom
| | - P Fouquet
- Institute Laue-Langevin, 6 rue Jules Horowitz, Boite Postale 156, 38042 Grenoble Cedex 9, France
| | - M Laver
- School of Metallurgy and Materials, University of Birmingham, B15 2TT, United Kingdom
| | - Ch Niedermayer
- Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - Y Su
- Jülich Centre for Neuton Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, D-85747 Garching, Germany
| | - K Nemkovski
- Jülich Centre for Neuton Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, D-85747 Garching, Germany
| | - M A Green
- School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom
| | - J A Rodriguez-Rivera
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
- Department of Materials Science, University of Maryland, College Park, Maryland 20742, USA
| | - J W Kim
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
| | - L Zhang
- Laboratory for Pohang Emergent Materials and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - S-W Cheong
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
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Petit S, Lhotel E, Damay F, Boutrouille P, Forget A, Colson D. Long-Range Order in the Dipolar XY Antiferromagnet Er_{2}Sn_{2}O_{7}. PHYSICAL REVIEW LETTERS 2017; 119:187202. [PMID: 29219561 DOI: 10.1103/physrevlett.119.187202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Indexed: 06/07/2023]
Abstract
Er_{2}Sn_{2}O_{7} remains a puzzling case among the extensively studied frustrated compounds of the rare-earth pyrochlore family. Indeed, while a first-order transition towards a long-range antiferromagnetic state with the so-called Palmer-Chalker structure is theoretically predicted, it has not yet been observed, leaving the issue as to whether it is a spin-liquid candidate open. We report on neutron scattering and magnetization measurements which evidence a second-order transition towards this Palmer-Chalker ordered state around 108 mK. Extreme care was taken to ensure a proper thermalization of the sample, which has proved to be crucial to successfully observe the magnetic Bragg peaks. At the transition, a gap opens in the excitations, superimposed on a strong quasielastic signal. The exchange parameters, refined from a spin-wave analysis in applied magnetic field, confirm that Er_{2}Sn_{2}O_{7} is a realization of the dipolar XY pyrochlore antiferromagnet. The proximity of competing phases and the strong XY anisotropy of the Er^{3+} magnetic moment might be at the origin of enhanced fluctuations, leading to the unexpected nature of the transition, the low ordering temperature, and the observed multiscale dynamics.
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Affiliation(s)
- S Petit
- Laboratoire Léon Brillouin, CEA, CNRS, Université Paris-Saclay, CE-Saclay, 91191 Gif-sur-Yvette, France
| | - E Lhotel
- Institut Néel, CNRS and Université Grenoble Alpes, 38042 Grenoble, France
| | - F Damay
- Laboratoire Léon Brillouin, CEA, CNRS, Université Paris-Saclay, CE-Saclay, 91191 Gif-sur-Yvette, France
| | - P Boutrouille
- Laboratoire Léon Brillouin, CEA, CNRS, Université Paris-Saclay, CE-Saclay, 91191 Gif-sur-Yvette, France
| | - A Forget
- Service de Physique de l'Etat Condensé, CEA, CNRS, Université Paris-Saclay, CE-Saclay, 91191 Gif-sur-Yvette, France
| | - D Colson
- Service de Physique de l'Etat Condensé, CEA, CNRS, Université Paris-Saclay, CE-Saclay, 91191 Gif-sur-Yvette, France
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Hirose HT, Yamaura JI, Hiroi Z. Robust ferromagnetism carried by antiferromagnetic domain walls. Sci Rep 2017; 7:42440. [PMID: 28195565 PMCID: PMC5308413 DOI: 10.1038/srep42440] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 01/08/2017] [Indexed: 11/09/2022] Open
Abstract
Ferroic materials, such as ferromagnetic or ferroelectric materials, have been utilized as recording media for memory devices. A recent trend for downsizing, however, requires an alternative, because ferroic orders tend to become unstable for miniaturization. The domain wall nanoelectronics is a new developing direction for next-generation devices, in which atomic domain walls, rather than conventional, large domains themselves, are the active elements. Here we show that atomically thin magnetic domain walls generated in the antiferromagnetic insulator Cd2Os2O7 carry unusual ferromagnetic moments perpendicular to the wall as well as electron conductivity: the ferromagnetic moments are easily polarized even by a tiny field of 1 mT at high temperature, while, once cooled down, they are surprisingly robust even in an inverse magnetic field of 7 T. Thus, the magnetic domain walls could serve as a new-type of microscopic, switchable and electrically readable magnetic medium which is potentially important for future applications in the domain wall nanoelectronics.
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Affiliation(s)
- Hishiro T Hirose
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Jun-Ichi Yamaura
- Material Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8503, Japan
| | - Zenji Hiroi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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Tardif S, Takeshita S, Ohsumi H, Yamaura JI, Okuyama D, Hiroi Z, Takata M, Arima TH. All-in-all-out magnetic domains: x-ray diffraction imaging and magnetic field control. PHYSICAL REVIEW LETTERS 2015; 114:147205. [PMID: 25910160 DOI: 10.1103/physrevlett.114.147205] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Indexed: 06/04/2023]
Abstract
Long-range noncollinear all-in-all-out magnetic order has been directly observed for the first time in real space in the pyrochlore Cd_{2}Os_{2}O_{7} using resonant magnetic microdiffraction at the Os L_{3} edge. Two different antiferromagnetic domains related by time-reversal symmetry could be distinguished and have been mapped within the same single crystal. The two types of domains are akin to magnetic twins and were expected-yet unobserved so far-in the all-in-all-out model. Even though the magnetic domains are antiferromagnetic, we show that their distribution can be controlled using a magnetic field-cooling procedure.
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Affiliation(s)
| | | | | | | | | | - Zenji Hiroi
- ISSP, University of Tokyo, Kashiwa 277-8581, Japan
| | - Masaki Takata
- RIKEN, SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- Department of Advanced Materials Science, University of Tokyo, Kashiwa 277-8561, Japan
- JASRI, SPring-8, Sayo, Hyogo 679-5148, Japan
| | - Taka-hisa Arima
- RIKEN, SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- RIKEN, CEMS, Wako, Saitama 351-0198, Japan
- Department of Advanced Materials Science, University of Tokyo, Kashiwa 277-8561, Japan
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Candidate quantum spin liquid due to dimensional reduction of a two-dimensional honeycomb lattice. Sci Rep 2014; 4:6451. [PMID: 25245216 PMCID: PMC5377320 DOI: 10.1038/srep06451] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 09/02/2014] [Indexed: 11/11/2022] Open
Abstract
As with quantum spin liquids based on two-dimensional triangular and kagome lattices, the two-dimensional honeycomb lattice with either a strong spin-orbital coupling or a frustrating second-nearest-neighbor coupling is expected to be a source of candidate quantum spin liquids. An ammonium salt [(C3H7)3NH]2[Cu2(C2O4)3](H2O)2.2 containing hexagonal layers of Cu2+ was obtained from solution. No structural transition or long-range magnetic ordering was observed from 290 K to 2 K from single crystal X-ray diffraction, specific heat and susceptibility measurements. The anionic layers are separated by sheets of ammonium and H2O with distance of 3.5 Å and no significant interaction between anionic layers. The two-dimensional honeycomb lattice is constructed from Jahn-Teller distorted Cu2+ and oxalate anions, showing a strong antiferromagnetic interaction between S = 1/2 metal atoms with θ = −120 (1) K. Orbital analysis of the Cu2+ interactions through the oxalate-bridges suggests a stripe mode pattern of coupling with weak ferromagnetic interaction along the b axis, and strong antiferromagnetic interaction along the a axis. Analysis of the magnetic susceptibility shows that it is dominated by a quasi-one-dimensional contribution with spin chains that are at least as well isolated as those of well-known quasi-one-dimensional spin liquids.
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