| Project/Area Number |
16K14231
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| Research Category |
Grant-in-Aid for Challenging Exploratory Research
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| Allocation Type | Multi-year Fund |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | Kyoto University |
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Principal Investigator |
Ando Yuichiro 京都大学, 工学研究科, 特定准教授 (50618361)
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Fiscal Year 2018: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2017: ¥520,000 (Direct Cost: ¥400,000、Indirect Cost: ¥120,000)
Fiscal Year 2016: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
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| Keywords | トポロジカル絶縁体 / スピントロニクス / 熱電素子 / 熱電 / スピン流 / 熱電変換 / 熱スピン変換 |
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| Outline of Final Research Achievements |
Topological insulators have a two dimensional metallic surface states whereas the bulk states exhibit insulating behaviors. Here, we investigated interconversion between spin currents and thermal gradient, and that between charge current and thermal gradient. Firstly, highly efficient spin-charge conversion was demonstrated by using copper based lateral spin valves, indicating highly efficient conversion between thermal gradient and spin current, because the bulk states of topological insulators has a large Seebeck coefficient and low electrical conductivity. We also established an accurate way to estimate of interconversion efficiency between thermal gradient and spin current. Generally, it is investigated by means of lock-in technique, however it includes non-negligible error if the current-voltage properties have nonlinear properties. By using combination of DC and Lock-in techniques, we successfully distinguished the thermal induced spin signals and the spurious signals.
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| Academic Significance and Societal Importance of the Research Achievements |
一般的な熱電素子の性能はその材料の電子の密度に比例して性能向上する成分と反比例する成分とがあり，電子密度による性能向上は困難でした．本問題を解決しようというのが本研究の目的です．トポロジカル絶縁体のバルク部分は絶縁体的であり，熱伝導率が小さく，ゼーベック係数が大きいという熱電材料に適した性質を有しています．一方，表面状態は電気抵抗率が低くこちらも熱電材料に適した性質を持っています．これらを組み合わせればこれまでの熱電素子には実現しえなかった新しい性能を得ることができるのではと期待しています．
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