2020 Fiscal Year Final Research Report
Quantum transport phenomena of ferromagnetic two dimensional electron system by gas source MBE films
| Project/Area Number |
18H01878
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 29020:Thin film/surface and interfacial physical properties-related
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| Research Institution | Institute of Physical and Chemical Research |
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Principal Investigator |
Takahashi Kei 国立研究開発法人理化学研究所, 創発物性科学研究センター, 上級研究員 (90469932)
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Keywords | 分子線エピタキシー / 酸化物薄膜 / 量子伝導 / 強磁性 / スピン偏極電子 |
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| Outline of Final Research Achievements |
By fabricating high quality films of EuTiO3 using gas source molecular beam epitaxy, we tried to observe quantum transport phenomena and quantum Hall effect in the magnetic semiconductor.
Compressive strained films on LSAT substrate show peculiar anomalous Hall effect during the magnetization process from antiferromagnetic order to ferromagnetic one. The Weyl nodes path through the Fermi energy during the magnetization process. I found that such process causes the magnetic field dependence of anomalous Hall effect. On lattice matched substrate SrTiO3, the mobility of La doped EuTiO3 film reaches 3200 cm2V-1s-1 at 2 K, which is the record of this system. This is demonstrated by measuring the Shubnikov de Haas (SdH) oscillations in the ferromagnetic state. Using first-principles calculations, it is shown that the observed SdH oscillations originate genuinely from Ti 3d-t2g states which are fully spin-polarized due to their energetical proximity to the in-gap Eu 4f bands.
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| Free Research Field |
酸化物エレクトロニクス
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| Academic Significance and Societal Importance of the Research Achievements |
磁性半導体はスピントロニクス応用材料として期待されている。スピントロニクスは電子のスピン自由度をデバイスに応用するが、電子には量子効果、つまり電子の波の性質がある。この量子効果を使うことで電子に機能をさらに持たせることができる。通常、磁性半導体は磁性不純物をドープするためその不純物散乱により移動度が低下し、電子の波の性質を反映した量子干渉効果を観察することは困難であった。磁性半導体EuTiO3が量子常誘電体であり電子ドープしたときの移動度が高いことに注目し、スピン偏極電子の量子伝導の観察に成功した本研究は、今後スピントロニクスに量子効果を取り入れた応用研究への貢献が期待できる。
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