2021 Fiscal Year Research-status Report
量子井戸効果を用いたスピン軌道トルクの制御：電流―スピン流変換の新しい自由度
| Project/Area Number |
21K14523
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| Research Institution | Tohoku University |
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Principal Investigator |
杜 野 東北大学, 先端スピントロニクス研究開発センター, 学術研究員 (70795319)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | Spin-orbit torque / Quantum confinement / Spin current |
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| Outline of Annual Research Achievements |
The current-induced spin-orbit torque (SOT) has been shown to be an efficient means to control the local magnetization electrically. On one hand, efficient spin-current generation using high-conductivity materials is desirable to achieve small energy loss; on the other hand, the ability to control the sign of the effective spin Hall angle may stimulate new spintronic functions. Here in this proposal, we aim to realize effective control (magnitude and sign) of spin-current generation in high-conductivity magnetic hetero-structures via a coherent control of electron spin (e.g. the quantum-confinement effect). Firstly, we have successfully prepared epitaxial Cu/Co bilayers upon a MgO substrate. Thin films show desirable interlayer flatness. Secondly, we have fabricated magnetic devices by using such bilayers and studied the current-induced SOT. The SOT measurement procedure has been optimized. As a result, we have found that both the magnitude and sign of the SOT oscillate with varying Cu thickness. This suggests that it is possible to manipulate the spin-current generation by taking advantage of the Cu band structure (Fermi surface). Our study potentially adds a new degree of freedom to the control of charge-spin current generation in high-conductivity magnetic hetero-structures.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
We successfully prepared epitaxial Cu/Co bilayers and studied the current-induced spin-orbit torque (SOT) in such magnetic hetero-structures. As a result, we found both the magnitude and sign of SOT oscillate as a function of Cu thickness. The results are consistent with our expectation. Therefore, our project is progressing smoothly.
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| Strategy for Future Research Activity |
On one hand, we aim to gain a better physical understanding of the current experimental results. This can be achieved by collaborating with theoretical researchers working on the current-induced spin-orbit torque (SOT). The mechanism of the SOT oscillation via the quantum confinement effect will be explored. On the other hand, we aim to prepare higher-quality magnetic hetero-structures by using the molecular-beam epitaxy technique (the present material preparation method is magnetron sputtering). With this technique, electron quantum confinement channel is expected to have longer mean free path and more pronounced effect on the SOT manipulation will be anticipated.
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| Causes of Carryover |
物品の納期が延期され、年度内の支払いはできなくなり、残額は次年度の物品費（基板など）として使用します。
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Research Products
(1 results)
