title: Exciton valley dynamics in monolayer WSe2probed by the two-color ultrafast Kerr rotation.
abstract: The newly developed two-dimensional layered materials provide a perfect platform for valley-spintronics exploration. To determine the prospect of utilizing the valley degree of freedom, it is of great importance to directly detect and understand the valley dynamics in these materials. Here, the exciton valley dynamics in monolayer WSe2is investigated by the two-color pump-probe magneto-optical Kerr technique. By tuning the probe photon energy in resonance with the free excitons and trions, the valley relaxation time of different excitonic states in monolayer WSe2is determined. Valley relaxation time of the free exciton in monolayer WSe2is confirmed to be several picoseconds. A slow valley polarization relaxation process is observed to be associated with the trions, showing that the valley lifetime for trions is one order of magnitude longer than that of free excitons. This finding suggests that trion can be a good candidate for valleytronics applications.
authors.affiliation: State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, P. R. China.
authors.forename: Tengfei
authors.identifier: http://orcid.org/0000-0002-1102-736X
authors.initials: T
authors.lastname: Yan
authors.affiliation: State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, P. R. China.
authors.forename: Jialiang
authors.initials: J
authors.lastname: Ye
authors.affiliation: State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, P. R. China.
authors.forename: Xiaofen
authors.initials: X
authors.lastname: Qiao
authors.affiliation: State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, P. R. China and College of Materials Science and Opto-electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, P. R. China. xinhuiz@semi.ac.cn.
authors.forename: Pingheng
authors.initials: P
authors.lastname: Tan
authors.affiliation: State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, P. R. China and College of Materials Science and Opto-electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, P. R. China. xinhuiz@semi.ac.cn.
authors.forename: Xinhui
authors.identifier: http://orcid.org/0000-0002-5888-3841
authors.initials: X
authors.lastname: Zhang