| Project/Area Number |
19F19815
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| Research Category |
Grant-in-Aid for JSPS Fellows
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| Allocation Type | Single-year Grants |
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| Section | 外国 |
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| Review Section |
Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
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| Research Institution | Institute of Physical and Chemical Research |
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Principal Investigator |
永長 直人 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, グループディレクター (60164406)
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| Co-Investigator(Kenkyū-buntansha) |
MASELL JAN 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, 外国人特別研究員
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| Project Period (FY) |
2019-11-08 – 2022-03-31
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| Project Status |
Completed (Fiscal Year 2021)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 2021: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2020: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2019: ¥600,000 (Direct Cost: ¥600,000)
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| Keywords | skyrmions / micromagnetics / simulations / topology / helimagnetism / spintronics / Nernst effect / scalar spin chirality / スキルミオン / トポロジカルなスピン構造 |
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| Outline of Research at the Start |
スキルミオンをはじめとするトポロジカルなスピン構造が様々な磁性体において発見され、その相図構造が調べられている。一方、トポロジカルに異なる相の間の変化はダイナミクスの問題となり、より高度な理論的解析を必要とする。従来は、ポテンシャル障壁によって遷移確率が決まるとされるが、エントロピーに対応する経路の数を考慮に入れることが必要となる。
本研究では、スキルミオンが強磁性状態などのトポロジカルに自明な状態へと崩壊する寿命を、これらの因子を取り入れて精度よく理論的に計算する手法を確立し、数値シミュレーション結果と併用することでトポロジカルな相変化の全貌を明らかにする。
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| Outline of Annual Research Achievements |
In my original proposal for the fiscal year 2021, I planned to continue my collaborations on (1)the three-dimensional texture of skyrmions as well as the collaborations on (2)the effects of thermally activated scalar spin chirality on atomic lattices. Moreover, I planned to study the effects of temperature and temperature gradients on the motion of skyrmions, supporting recent experimental results at RIKEN.
On the end of (1), I have worked on various different topics, exploiting the computational power of my modified version of the open source simulation tool MuMax3. I could explain the unusual experimental observations at topological defects in the helical (lamellar) phase of chiral magnets and, in a different project, explain the stability of skyrmions and antiskyrmions in an experimentally mapped out series of various material compositions. Moreover, a work on the current-induced distortion of skyrmions pinned at defects is under review, as well as a work on the electrical and spin currents induced by the motion of a magnetic screw.
Our first work on the large Hall and Nernst effects induced by (2) has also been published and subsequent projects were initiated. However, my program for simulating the thermal Hall effect in such systems is not ready for use yet.
Finally, I also tried the motion of skyrmions in temperature gradient which was described in previous theories which,but failed to explain experimental observations at RIKEN.I corrected small errors in these previous and combined the results with a compensate theory for error, which finally described the experiments.
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| Research Progress Status |
令和3年度が最終年度であるため、記入しない。
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| Strategy for Future Research Activity |
令和3年度が最終年度であるため、記入しない。
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