https://scholars.lib.ntu.edu.tw/handle/123456789/626511
標題: | Valley-dependent exciton fine structure and Autler-Townes doublets from Berry phases in monolayer MoSe2 | 作者: | CHAW-KEONG YONG Utama, M Iqbal Bakti Ong, Chin Shen Cao, Ting Regan, Emma C Horng, Jason Shen, Yuxia Cai, Hui Watanabe, Kenji Taniguchi, Takashi Tongay, Sefaattin Deng, Hui Zettl, Alex Louie, Steven G Wang, Feng |
關鍵字: | QUASI-PARTICLE; POLARIZATION | 公開日期: | 十月-2019 | 出版社: | NATURE PUBLISHING GROUP | 卷: | 18 | 期: | 10 | 起(迄)頁: | 1065 | 來源出版物: | Nature materials | 摘要: | The Berry phase of Bloch states can have profound effects on electron dynamics1-3 and lead to novel transport phenomena, such as the anomalous Hall effect and the valley Hall effect4-6. Recently, it was predicted that the Berry phase effect can also modify the exciton states in transition metal dichalcogenide monolayers, and lift the energy degeneracy of exciton states with opposite angular momentum through an effective valley-orbital coupling1,7-11. Here, we report the observation and control of the Berry phase-induced splitting of the 2p exciton states in monolayer molybdenum diselenide (MoSe2) using the intraexciton optical Stark spectroscopy. We observe the time-reversal-symmetric analogue of the orbital Zeeman effect resulting from the valley-dependent Berry phase, which leads to energy difference of +14 (-14) meV between the 2p+ and 2p- exciton states in the K (K') valley, consistent with the ordering from our ab initio GW-Bethe-Salpeter equation results. In addition, we show that the light-matter coupling between intraexciton states is remarkably strong, leading to a prominent valley-dependent Autler-Townes doublet under resonant driving. Our study opens up pathways to coherently manipulate the quantum states and excitonic excitation with infrared radiation in two-dimensional semiconductors. |
URI: | https://scholars.lib.ntu.edu.tw/handle/123456789/626511 | ISSN: | 1476-1122 | DOI: | 10.1038/s41563-019-0447-8 |
顯示於: | 物理學系 |
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