| 研究実績の概要 |
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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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
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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| 今後の研究の推進方策 |
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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