2019 Fiscal Year Final Research Report
Determination of magnon dispersion and lifetime of spin-Seebeck insulators
| Project/Area Number |
19K21031
|
|---|
| Project/Area Number (Other) |
18H05841 (2018)
|
|---|
| Research Category |
Grant-in-Aid for Research Activity Start-up
|
| Allocation Type | Multi-year Fund (2019)
Single-year Grants (2018) |
|---|
| Review Section |
0202:Condensed matter physics, plasma science, nuclear engineering, earth resources engineering, energy engineering, and related fields
|
|---|
| Research Institution | Tohoku University |
|---|
Principal Investigator |
Kikkawa Takashi 東北大学, 材料科学高等研究所, 助教 (60828846)
|
|---|
| Project Period (FY) |
2018-08-24 – 2020-03-31
|
| Keywords | スピントロニクス / スピンゼーベック効果 / マグノン / 磁性ガーネット / 中性子散乱 / スピン流 |
|---|
| Outline of Final Research Achievements |
In this research, we investigate the magnetic excitation characteristics (dispersion relations and quasiparticle lifetime) of magnetic garnets by means of neutron scattering techniques and so on. Based on the results, we aim to obtain deep understanding of the spin Seebeck effect (SSE), in which such magnonic properties play an essential role. Through this research, we revealed the magnetic excitations of Y3Fe5O12(YIG) and Tb3Fe5O12(TbIG), and by combining the results with theoretical calculations based on an LLG equation, we found that the temperature-dependent SSE features in these materials can be understood in terms of their magnon excitation characteristics. Furthermore, in a Bi-Ga substituted LuIG system, we observed a strong enhancement of SSE at a low field induced by magnon-phonon hybridization and explained it in terms of change of the magnon dispersion and reduced magnon lifetime caused by the non-magnetic ions substitution into Fe sites of LuIG.
|
| Free Research Field |
スピントロニクス
|
| Academic Significance and Societal Importance of the Research Achievements |
本研究により、物性物理学の重要概念である“素励起”という観点から、熱スピン変換現象を包括的に理解するための指針が得られた。絶縁体スピントロニクス分野の基盤材料であるイットリウム鉄ガーネットYIGのマグノン分極を初めて観測したことは意義深く、今後本手法を利用して、より複雑な磁気構造をもつ材料のマグノン分散・分極の検出が期待されている。また本研究を通じて、これまで関係性が希薄であった中性子などを利用する量子ビーム分野とスピントロニクス分野とが有機的に結合していくための端緒が開かれたと言える。
|
