| Project/Area Number |
18K13495
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
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| Research Institution | The University of Tokyo |
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Principal Investigator |
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2020: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2019: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2018: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
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| Keywords | 電荷密度波 / 自由エネルギー / 光誘起相転移 / 光物性 / 遷移金属ダイカルコゲナイド / 非平衡現象 / 時間結晶 / 準安定状態 / 非平衡物理 |
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| Outline of Final Research Achievements |
The charge density wave states of the layered transition metal dichalcogenides TaS2 and TaSe2 and their derived problems were theoretically studied. For the microscopic theory, we constructed a model that well represents these materials and clarified the melting and lattice deformation of the charge density wave induced by laser application. As for the phenomenology, we discovered previously unknown minimal points by detailed analysis of the conventional free energy, and showed that they correspond to structures similar to the metastable states observed experimentally. By extending this theory to a time-dependent one, we have developed a theory to investigate the spatio-temporal structure of the phase transition dynamics of charge density wave states. As derivative problems, we clarified the relationship between charge density waves and high-harmonic generation, and a new generation mechanism of time crystals.
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| Academic Significance and Societal Importance of the Research Achievements |
1T-TaS2の光誘起初期ダイナミクスの理論計算については、類似の研究がほとんどなく、この物質の非平衡現象を解明する上で一つの貢献になった。現象論で見出した極小点および時間依存理論の構築については、伝統的な自由エネルギー理論に内在していた強力な予言能力に光を当て、最新の実験結果への適用可能性を示すものであり、今後の層状物質の研究に役立つものと思われる。高次高調波発生については、電荷密度波がこれを増強することが分かり、周波数変換素子への応用に繋がる可能性がある。時間結晶については、電荷密度波との類似性が明らかになったことで、物理学における時間と空間の等価性の現れの１つであり大変興味深い。
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