2019 Fiscal Year Annual Research Report
Characterization of Coupling between Mechanical Angular Momentum and Electron Spin
| Project/Area Number |
19J21720
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| Research Institution | The University of Tokyo |
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Principal Investigator |
許 明然 東京大学, 新領域創成科学 研究科, 特別研究員(DC1)
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| Project Period (FY) |
2019-04-25 – 2022-03-31
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| Keywords | Nonreciprocity / Magneto-rotation / Suface acoustic waves |
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| Outline of Annual Research Achievements |
Magnon-phonon coupling (MPC) has attracted enormous attention in recent years. However, the form of MPC has been limited to magneto-elastic coupling (MEC). In fact, there is an alternative path, namely, magneto-rotation coupling (MRC), which was first proposed in 1976[AIP Conference Proceedings 29, 542 (1976)] but so far has been elusive. MRC originates from the magnon emission induced by rotationally deformed magnetic lattice, which applies to all the magnetic material. Thus, to break the symmetry of the propagation, we employ magneto-rotation coupling to capture the chirality of the acoustic waves in a perpendicularly anisotropic ultra-thin film Ta/CoFeB(1.6 nm)/MgO, achieving a giant nonreciprocal acoustic wave attenuation with a rectification ratio up to 77%.
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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
Currently, we have achieved the first two-step, optimization of the device, and demonstration of magneto-rotation coupling(MRC). However, there are still many unknowns in the coupling between rotation with spin. Thus, we are now working on the second stage of the project, extending our study to a broader perspective. More specifically, to explore the functionality, we are working on the electric modulation of MRC. From the theoretical point of view, it is possible to modulate MRC if the magnetic anisotropy is controllable. Towards this direction, at the moment, we employ the ultra-thin CoFeB/MgO film, which is famous for its electrically modulable magnetic anisotropy energy, examing the possibility and also the efficiency of the controllable MRC.
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| Strategy for Future Research Activity |
In recent years, Spin conversion has attracted intense attention from the industry. However, currently, there are only a few successful applications based on it. For the future work of this study, we plan to start a direction which guides to a real application.
Noise-canceling has been a popular function in market for many years. However, the basic mechanism behind remains the same. Namely, active noise canceling(ANC). It requires a sensitive micro mic and speaker to capture the noise and send an anti-noise signal. In need of a more compacted device and longer using time, ANC does not seem ideal. However, Magnon- rotation coupling is a passive method and requires no external source to block the coming acoustic waves.
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[Presentation] Spintronics Lectures, Magnetoelastic effect, surface acoustic waves, and magnon-phonon coupling2019
Author(s)
Mingran Xu, Kei Yamamoto, Jorge Puebla, Korbinian Baumgaertl, Bivas Rana, Katsuya Miura, Hiromasa Takahashi, Dirk Grundler, Sadamichi Maekawa, Yoshichika Otani.
Organizer
Spintronics Lectures
Int'l Joint Research
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