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Xu L, Li X, Lu X, Collignon C, Fu H, Koo J, Fauqué B, Yan B, Zhu Z, Behnia K. Finite-temperature violation of the anomalous transverse Wiedemann-Franz law. Sci Adv 2020; 6:eaaz3522. [PMID: 32494640 PMCID: PMC7182422 DOI: 10.1126/sciadv.aaz3522] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 01/17/2020] [Indexed: 05/12/2023]
Abstract
The Wiedemann-Franz (WF) law has been tested in numerous solids, but the extent of its relevance to the anomalous transverse transport and the topological nature of the wave function, remains an open question. Here, we present a study of anomalous transverse response in the noncollinear antiferromagnet Mn3Ge extended from room temperature down to sub-kelvin temperature and find that the anomalous Lorenz ratio remains close to the Sommerfeld value up to 100 K but not above. The finite-temperature violation of the WF correlation is caused by a mismatch between the thermal and electrical summations of the Berry curvature and not by inelastic scattering. This interpretation is backed by our theoretical calculations, which reveals a competition between the temperature and the Berry curvature distribution. The data accuracy is supported by verifying the anomalous Bridgman relation. The anomalous Lorenz ratio is thus an extremely sensitive probe of the Berry spectrum of a solid.
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Affiliation(s)
- Liangcai Xu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Xiaokang Li
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
- Laboratoire de Physique et d'Etude des Matériaux (CNRS), ESPCI Paris, PSL Research University, 75005 Paris, France
| | - Xiufang Lu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Clément Collignon
- Laboratoire de Physique et d'Etude des Matériaux (CNRS), ESPCI Paris, PSL Research University, 75005 Paris, France
- JEIP, USR 3573 CNRS, Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France
| | - Huixia Fu
- Department of Condensed Matter Physics, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Jahyun Koo
- Department of Condensed Matter Physics, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Benoît Fauqué
- Laboratoire de Physique et d'Etude des Matériaux (CNRS), ESPCI Paris, PSL Research University, 75005 Paris, France
- JEIP, USR 3573 CNRS, Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France
| | - Binghai Yan
- Department of Condensed Matter Physics, Weizmann Institute of Science, 7610001 Rehovot, Israel
- Corresponding author. (B.Y.); (Z.Z.); (K.B.)
| | - Zengwei Zhu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
- Corresponding author. (B.Y.); (Z.Z.); (K.B.)
| | - Kamran Behnia
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
- Laboratoire de Physique et d'Etude des Matériaux (CNRS), ESPCI Paris, PSL Research University, 75005 Paris, France
- II. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany
- Corresponding author. (B.Y.); (Z.Z.); (K.B.)
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Fu H, Liu CX, Yan B. Exchange bias and quantum anomalous nomalous Hall effect in the MnBi 2Te 4/CrI 3 heterostructure. Sci Adv 2020; 6:eaaz0948. [PMID: 32181356 PMCID: PMC7060064 DOI: 10.1126/sciadv.aaz0948] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 12/11/2019] [Indexed: 05/31/2023]
Abstract
The layered antiferromagnetic MnBi2Te4 films have been proposed to be an intrinsic quantum anomalous Hall (QAH) insulator with a large gap. It is crucial to open a magnetic gap of surface states. However, recent experiments have observed gapless surface states, indicating the absence of out-of-plane surface magnetism, and thus, the quantized Hall resistance can only be achieved at the magnetic field above 6 T. We propose to induce out-of-plane surface magnetism of MnBi2Te4 films via the magnetic proximity with magnetic insulator CrI3. A strong exchange bias of ∼40 meV originates from the long Cr-eg orbital tails that hybridize strongly with Te p orbitals. By stabilizing surface magnetism, the QAH effect can be realized in the MnBi2Te4/CrI3 heterostructure. Moreover, the high-Chern number QAH state can be achieved by controlling external electric gates. Thus, the MnBi2Te4/CrI3 heterostructure provides a promising platform to realize the electrically tunable zero-field QAH effect.
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Affiliation(s)
- Huixia Fu
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Chao-Xing Liu
- Department of Physics, the Pennsylvania State University, University Park, PA 16802, USA
| | - Binghai Yan
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
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