Generation of coherent phonon-anglular-momentum state by using light and terahertz wave

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01018
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 13020:Semiconductors, optical properties of condensed matter and atomic physics-related
• Research Institution: Ritsumeikan University
• Principal Investigator: Koreeda Akitoshi 立命館大学, 理工学部, 教授 (40323878)
• Co-Investigator(Kenkyū-buntansha): 藤井 康裕 立命館大学, 理工学部, 講師 (50432050) ; 野竹 孝志 石巻専修大学, 理工学部, 准教授 (70413995) ; 大野 誠吾 東北大学, 理学研究科, 助教 (70435634)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: フォノン / コヒーレントフォノン / カイラルフォノン / ラマン散乱 / テラヘルツ波

Outline of Final Research Achievements

As a result of spontaneous circularly polarized Raman scattering experiments in alpha-quartz, many phonon modes were found that they exchange angular momenta with photonos. We found that photons and phonons actually exchange angular momenta, and that the law of conservation of angular momentum is necessary in the Raman selection rules. In controlling the wavefront of terahertz waves, it was experimentally confirmed that an optical vortex arrangement is generated by moire structures, and that light acquires a topological charge due to a chiral structure in a focusing optical system. Using backward parametric processes, we were able to establish core technologies for ultra-high sensitivity detection and cascade wavelength conversion of sub-terahertz waves in the 0.3 GHz band.

Free Research Field

固体物性

Academic Significance and Societal Importance of the Research Achievements

角運動量（擬角運動量）を持つフォノンはカイラルフォノンと呼ばれるようになった．カイラルフォノンは磁場を感じると考えられるため，物質中に電子由来の磁気モーメントや磁気的秩序が存在すれば，これらと強く相互作用することが期待され，フォノン物性の立場から，電気・磁気・スピン・熱デバイス応用に対するまったく新しい原理的アプローチを提案できると考える．非磁性体でのコヒーレントフォノン角運動量状態の励振を端緒とし，スピン的and/or軌道的フォノンとスピン波（マグノン）との相互作用を通した，誘電的・磁気的秩序の制御などへとつながる基礎的知見を収集できたと考える．