https://scholars.lib.ntu.edu.tw/handle/123456789/626518
標題: | Biexcitonic optical Stark effects in monolayer molybdenum diselenide | 作者: | CHAW-KEONG YONG Horng, J Shen, YX Cai, H LON A. WANG Yang, CS Lin, CK Zhao, SL Watanabe, K Taniguchi, T Tongay, S Wang, F |
關鍵字: | ELECTRON-SPIN; MANIPULATION; EXCITONS; FIELD; MOS2 | 公開日期: | 2018 | 出版社: | NATURE PUBLISHING GROUP | 卷: | 14 | 期: | 11 | 起(迄)頁: | 1092 | 來源出版物: | NATURE PHYSICS | 摘要: | Floquet states, where a periodic optical field coherently drives electrons in solids 1–3 , can enable novel quantum states of matter 4–6 . A prominent approach to realize Floquet states is based on the optical Stark effect. Previous studies on the optical Stark effect often treated the excited state in solids as free quasi-particles 3,7–12 . However, exciton–exciton interactions can be sizeably enhanced in low-dimensional systems and may lead to light–matter interactions that are qualitatively different from those in the non-interacting picture. Here we use monolayer molybdenum diselenide (MoSe 2 ) as a model system to demonstrate that the driving optical field can couple a hierarchy of excitonic states, and the many-body inter-valley biexciton state plays a dominant role in the optical Stark effect. Specifically, the exciton–biexciton coupling in monolayer MoSe 2 breaks down the valley selection rules based on the non-interacting exciton picture. The photon-dressed excitonic states exhibit an energy redshift, splitting or blueshift as the driving photon frequency varies below the exciton transition. We determine a binding energy of 21 meV for the inter-valley biexciton and a transition dipole moment of 9.3 debye for the exciton–biexciton transition. Our study reveals the crucial role of many-body effects in coherent light–matter interaction in atomically thin two-dimensional materials. |
URI: | https://scholars.lib.ntu.edu.tw/handle/123456789/626518 | ISSN: | 1745-2473 | DOI: | 10.1038/s41567-018-0216-7 |
顯示於: | 物理學系 |
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