Theory of Modulation of Effective Interactions and Coherent Manipulation of Electronic States by Strong Optical Fields

2021 Fiscal Year Final Research Report

• Project/Area Number: 16K05459
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Chuo University
• Principal Investigator: Yonemitsu Kenji 中央大学, 理工学部, 教授 (60270823)
• Project Period (FY): 2016-04-01 – 2022-03-31
• Keywords: 有機導体 / 量子スピン液体 / 光誘起相転移 / 動的局在 / 非線形同期振動 / 逆ファラデー効果

Outline of Final Research Achievements

For organic conductors with α-type structure, it is shown that photoinduced transient charge order requires not only dynamical localization that suppresses electronic mobility but also electron-electron interactions that compete with the electronic mobility. For organic conductors with κ-type dimerized structure, after strong photoexcitation that produces large charge disproportionation, charge oscillations are synchronized through electron-electron interactions, and a stimulated emission occurs. The mechanism is clarified through numerical simulations and an analysis of equations of charge motion. Furthermore, for a multi-orbital electron system on a honeycomb lattice that exhibits a quantum-spin-liquid state, the inverse Faraday effect is observed, where a circularly polarized light field produces magnetization perpendicular to the lattice. This fact is demonstrated by calculations of photoinduced magnetization dynamics, and its origin is clarified by quantum Floquet theory.

Free Research Field

物性理論

Academic Significance and Societal Importance of the Research Achievements

強い光をとても短い時間だけ物質に照射することで起きる変化を理論的に示した。そのうち空間反転対称性を破るもの（過渡的に電荷分極をつくるもの）と時間反転対称性を破るもの（過渡的に磁化をつくるもの）は実現している。用いたエネルギー（あるいは振動数）の光では直接的に電子を動かし、上述の巨視的変化はともに電子が隣の原子に移動する程度の時間内で超高速に起きている。このように、多数の電子を一斉にかつ直接的に操作する方法とその帰結を、量子多体理論から明らかにし、共同研究により実証した。