2019 Fiscal Year Final Research Report
Investigation of unconventional superconducting phenomena induced in ferromagnetic semiconductors
| Project/Area Number |
17K05492
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Condensed matter physics I
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| Research Institution | The University of Tokyo |
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Principal Investigator |
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Keywords | 超伝導接合 / 半導体 / 磁性 / ジョセフソン効果 / 近接効果 / スピン三重項超伝導 |
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| Outline of Final Research Achievements |
We fabricated superconducting junctions with a ferromagnetic semiconductor (In,Fe)As and conventional superconductor Nb. We observed that the resistance reaches zero down to the lowest temperature of 0.1 K. The current-voltage characteristics of the junction evidenced that the zero resistance originates from the Josephson effect. This is the first observation of the supercurrent in ferromagnetic semiconductors. We also measured the field dependence and temperature dependence of the critical current and demonstrated that the induced superconductivity in the ferromagnetic semiconductor is due to the spin-triplet Cooper pairing.
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| Free Research Field |
固体物理学
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| Academic Significance and Societal Importance of the Research Achievements |
本研究はこれまで困難であった強磁性半導体中での超伝導近接効果と有限の超伝導電流の観測に世界で初めて成功した。強磁性半導体は強磁性金属と異なり、電場によって磁性を大きく変えることができるため、これを用いた超伝導接合では超伝導電流のスピン状態を電場で制御する、これまでにない画期的な超伝導デバイスの実現も期待できる。強磁性半導体はスピントロニクス材料としても有力であり、スピン三重項超伝導のスピントロニクスへの応用可能性も示すことができた。
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