| 研究課題/領域番号 |
23KJ0778
|
|---|
| 研究種目 |
特別研究員奨励費
|
| 配分区分 | 基金 |
|---|
| 応募区分 | 国内 |
|---|
| 審査区分 |
小区分13030:磁性、超伝導および強相関系関連
|
|---|
| 研究機関 | 東京大学 |
|---|
研究代表者 |
LIAO Liyang 東京大学, 新領域創成科学研究科, 特別研究員(DC1)
|
|---|
| 研究期間 (年度) |
2023-04-25 – 2026-03-31
|
| 研究課題ステータス |
交付 (2023年度)
|
| 配分額 *注記 |
4,200千円 (直接経費: 4,200千円)
2025年度: 1,400千円 (直接経費: 1,400千円)
2024年度: 1,400千円 (直接経費: 1,400千円)
2023年度: 1,400千円 (直接経費: 1,400千円)
|
|---|
| キーワード | Bosonic transport / Superlattice / Nonreciprocity / Symmetry breaking / Valley / magnon-phonon coupling |
|---|
| 研究開始時の研究の概要 |
The collective motion of magnetism, the spin waves, can couple to sound waves.In this research, we modulate the coupling between spin wave and sound wave by periodic arrays, who can coherently scatter these waves.We will firstly study the transmission of large samples, and then characterize the spin waves and sound waves directly by optical methods.
|
| 研究実績の概要 |
Bosonic transport is studied via surface acoustic wave transmission. By rotating surface acoustic wave propagation direction on 128-Y LiNbO3 substrate, Y' axis was selected for superlattice study for its suitable symmetry. Superlattice was then fabricated using electron beam lithography, e-beam evaporation and lift-off process.
Ni (20 nm) /Ti (15 nm) was used for the deposition. Square and hexagonal lattices with and without symmetry breaking are fabricated. The surface acoustic wave wavelength was 2000 nm, and the lattice size was selected accordingly, so that the wavevector located at the Brillouin zone corners.The transport efficiency spectrum was measured by the vector network analyzer, and a nonreciprocity controlled by out-of-plane magnetization and lattice symmetry was observed.
Systematic magnetic field manitude,angular,and frequency dependence were performed, clearly established the superlattice origin of the nonreciprocity. The nonreciprocity is controlled by the phononic band structures, as it change sign at the center of the phononic Dirac cone, consistant with the chirality change of the Dirac bands. Such frequency-dependent sign change of nonreciprocity in magnon-phonon coupling is observed for the first time. The results were summarized and published in Physical Review Letters.
|
| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
We achieved the nonreciprocal surface acoustic wave transport controlled by superlattice in this year, as a milestone of this project.
Baesd on this achievement, we can explore more possiblities in the further research.
|
| 今後の研究の推進方策 |
We will turn towards to more complicated superlattice structures, to tune the observed nonreciprocity. We will also try to combine the achieved global spectra measurement to local measurements, such as X-ray, NV center. In this way, we may be able to explore more exciting phenomena, such as topological chiral edge modes and Non-Hermitian skin effect.
|
