Spin-Valley Locking Effect in Defect States of Monolayer MoS<sub>2</sub>
Yaqian Wang, Longjiang Deng, Qilin Wei, Yi Wan, Zhen Liu, Xiao Lu, Yue Li, Lei Bi, Li Zhang, Haipeng Lu, Haiyan Chen, Peiheng Zhou, Linbo Zhang, Yingchun Cheng, Xiaoxu Zhao, Yu Ye, Wei Huang, Stephen J. Pennycook, Kian Ping Loh, Bo Peng
Abstract
Valley pseudospin in two-dimensional (2D) transition-metal dichalcogenides (TMDs) allows optical control of spin-valley polarization and intervalley quantum coherence. Defect states in TMDs give rise to new exciton features and theoretically exhibit spin-valley polarization; however, experimental achievement of this phenomenon remains challenges. Here, we report unambiguous valley pseudospin of defect-bound localized excitons in CVD-grown monolayer MoS2; enhanced valley Zeeman splitting with an effective g-factor of −6.2 is observed. Our results reveal that all five d-orbitals and the increased effective electron mass contribute to the band shift of defect states, demonstrating a new physics of the magnetic responses of defect-bound localized excitons, strikingly different from that of A excitons. Our work paves the way for the manipulation of the spin-valley degrees of freedom through defects toward valleytronic devices.