Ultrafast Dynamics of Spin Generation and Relaxation in Layered WSe2

被引:15
|
作者
Ye, Jialiang [1 ,2 ]
Li, Ying [1 ,2 ]
Yan, Tengfei [1 ]
Zhai, Guihao [1 ,2 ]
Zhang, Xinhui [1 ,2 ]
机构
[1] Chinese Acad Sci, Inst Semicond, State Key Lab Superlattices & Microstruct, Beijing 100083, Peoples R China
[2] Univ Chinese Acad Sci, Ctr Mat Sci & Optoelect Engn, Beijing 100049, Peoples R China
基金
中国国家自然科学基金;
关键词
VALLEY POLARIZATION; CARRIER DYNAMICS; MONO LAYER; MONOLAYER; COHERENCE;
D O I
10.1021/acs.jpclett.9b01068
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
We investigated the build-up and relaxation processes of spin-polarized A-and B-exciton dynamics in monolayer, bilayer, and bulk WSe2 using helicity-resolved two-color pump-probe spectroscopy. Substantial spin polarization was confirmed in bulk crystals, though the spin polarization degree of A excitons decreased from monolayer to bulk. However, the spin polarization of A excitons almost vanished in all different layered-flakes when resonantly pumping the B-exciton transition, owing to the dominant role of interexciton transfer. When resonantly pumping the A-exciton transition, the spin polarization of the up-converted B excitons was inverted in all layers because of the efficient Dexter-like coupling and phonon-assisted scattering. The same short spin relaxation time (1.8 +/- 0.2 ps) of A excitons was found for all studied flakes in the subsequent spin depolarization processes, which was ascribed to the active electron-phonon scattering resulting from the intrinsic small conduction-band spin-orbit coupling splitting in layered WSe2.
引用
收藏
页码:2963 / 2970
页数:15
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