2023 Fiscal Year Final Research Report
Quantum transport phenomena explored in 4f magnetic topological semimetal films
| Project/Area Number |
22K20353
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| Research Category |
Grant-in-Aid for Research Activity Start-up
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| Allocation Type | Multi-year Fund |
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| Review Section |
0202:Condensed matter physics, plasma science, nuclear engineering, earth resources engineering, energy engineering, and related fields
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
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| Project Period (FY) |
2022-08-31 – 2024-03-31
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| Keywords | トポロジカル半金属 / 薄膜 / 磁性 / ホール効果 |
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| Outline of Final Research Achievements |
This study aims to fabricate high-quality thin films and heterostructures of a group of materials that are expected to realize an ideal band structure as magnetic topological semimetals, and to elucidate quantum transport phenomena originating from the giant Berry phase and chirality of the Weyl point. We have experimentally clarified that EuCd2As2, initially predicted as an ideal Weyl semimetal candidate, has actually an energy gap. On the other hand, based on the films of Weyl semimetal EuCd2Sb2 hosting multiple Weyl point pairs, we have demonstrated that the Berry curvature distribution can be sensitively modulated such as by the magnetization process under field and by the direction of the applied magnetic field, leading to experimental observation of nonmonotonic magnetoresistance effect and in-plane anomalous Hall effect.
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| Free Research Field |
トポロジカル半金属
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| Academic Significance and Societal Importance of the Research Achievements |
ワイル点ペアを一つのみ持つ理想的な物質と当初予想されていたEuCd2As2の低キャリア濃度試料を実現し、実際にはバンドギャップを持つ絶縁体であることを実験的に示したことは、ワイル半金属相を前提としたこれまでの当該物質の先行研究の解釈を覆す重要な発見であると言える。また、ワイル半金属相を実現するEuCd2Sb2薄膜において得られた磁気抵抗効果や異常ホール効果は、4f系ワイル半金属物質の利点でもある磁気秩序の独立操作によってベリー曲率分布やそれに付随した量子輸送現象の制御や新規開拓が可能となることを示しており、今後のワイル半金属物質における機能性開拓の指針になると考えられる。
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