Elucidation and control of valley physics in atomically thin materials

2018 Fiscal Year Final Research Report

• Project/Area Number: 17H06786
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Single-year Grants
• Research Field: Condensed matter physics I
• Research Institution: Kyoto University
• Principal Investigator: Shinokita Keisuke 京都大学, エネルギー理工学研究所, 特定助教 (60806446)
• Project Period (FY): 2017-08-25 – 2019-03-31
• Keywords: 原子層物質 / バレートロニクス / 遷移金属ダイカルコゲナイド / 励起子

Outline of Final Research Achievements

Valley degrees of freedom of electrons and holes has recently attracted much interest in fundamental and applied research areas because of novel phenomena and their potential for next generation electronics device with high speed operation (valleytronics). This study focuses on elucidation and control of valley relaxation mechanism in monolayer transition metal dichalcogenides (MX2, M=Mo, W, X=S, Se) in which valley and spin degrees of freedom are coupled. By using device structure fabrication and spectroscopic technique, we obtained deep understanding of relaxation mechanism of valley polarized state and demonstrated proof of principle to achieve high valley polarization, which holds potential for novel valleytronics devices.

Free Research Field

ナノ光科学

Academic Significance and Societal Importance of the Research Achievements

本研究では、これまで未解明であった中性励起子のバレー分極率の緩和メカニズムを完全に解明し、バレー分極率を制御する新たな方法を実証した。また、荷電励起子のバレー分極状態の包括的な緩和ダイナミクスを明らかにした。これにより、荷電励起子のバレー分極状態緩和メカニズムの理論的な研究を推進して、将来のバレートロニクスデバイスの実現に向けての新たな知見を集積することができた。