Chirality-Dependent Valley Polarization in Magnetic van der Waals Heterostructures via Spin-Selective Charge Transfer.

Wu, Wei; Liu, Mengyu; Zhou, Jiangpeng; Li, Jin'an; Zhang, Yuxiang; Xu, Feiya; Li, Xu; Wu, Yaping et al. · Nano Lett · 2024

basic_science · Level V

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Abstract

Magnetic proximity interaction provides a promising route to manipulate the spin and valley degrees of freedom in van der Waals heterostructures. Here, we report a control of valley pseudospin in the WS<sub>2</sub>/MoSe<sub>2</sub> heterostructure by utilizing the magnetic proximity effect of few-layered CrBr<sub>3</sub> and, for the first time, observe a substantial difference in valley polarization of intra/interlayer excitons under different circularly polarized laser excitations, referred to as chirality-dependent valley polarization. Theoretical and experimental results reveal that the spin-selective charge transfer between MoSe<sub>2</sub> and CrBr<sub>3</sub>, as well as between MoSe<sub>2</sub> and WS<sub>2</sub>, is mostly responsible for the chiral feature of valley polarization in comparison with the proximity exchange field. This means that a long-distance manipulation of exciton behaviors in multilayer heterostructures can be achieved through spin-selective charge transfer. This work marks a significant advancement in the control of spin and valley pseudospin in multilayer structures.