2019/03/16 by Taishen Li, Tao Yu, Li, Taishen +18
Engineering · Materials Science · #2D Materials and Applications #Chalcogenide Semiconductor Thin Films #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Perovskite Materials and Applications
paper · pdf · doi:10.48550/arxiv.1903.06899
openalex publication_date 2019/03/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Manipulating and reserving the valley pseudospin of excitons is one core aim in the two-dimensional transition metal dichalcogenides (TMDs). However, due to the strong electron-hole exchange and spin-orbit coupling interactions, the exciton recombination lifetime is subject to picosecond timescale intrinsically, and the valley polarization is hardly modulated by a moderate magnetic field. It is fortunate that interlayer and defect-localized excitons promise to overcome these difficulties by suppressing the above interactions. Here we clearly reveal that the valley polarization can be reversed and revived in the defect-localized excitons with a microsecond lifetime in AB-stacked WSe2-WS2 heterobilayer. Specifically, for the interlayer defect-localized exciton, the valley polarization is reversed and can be efficiently enhanced by a weak out-of-plane magnetic field (<0.4 T). In sharp contrast, the valley polarization of the intralayer defect-localized exciton can revive after a fast decay process and follows the direction of the moderate out-of-plane magnetic field (<3 T). We explain the reversed valley polarization with highly magnetic sensitivity by the delocalization of defect-localized holes under a weak magnetic field and the revival of valley polarization by the valley Zeeman effect under a moderate magnetic field. Our results demonstrate that the valley pseudospin of defect-localized excitons can be efficiently modulated by the external magnetic field and enrich both the understanding and the technical approaches on manipulating the valley dynamics in TMDs and their heterostructure.