Tunable Proximity Valley Splitting Via Interfacial Exchange Pinning in WSe<sub>2</sub>-CrBr<sub>3</sub>-CrPS<sub>4</sub> Heterostructures.

Li, Shaofei; Xie, Xing; Chen, Junying; Zhang, Xian; Hou, Shikun; Zhang, Siyu; Luo, Jianyi; He, Jun et al. · Nano Lett · 2026

basic_science · Level V

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Abstract

Magnetic proximity effects in van der Waals heterostructures provide an optical route to manipulate valley pseudospins in transition-metal dichalcogenides, but abrupt switching of two-dimensional (2D) ferromagnets (FM) limits continuous valley modulation. We demonstrate that the proximity-induced valley response of WSe<sub>2</sub> can be modified by engineering the interfacial magnetic environment in WSe<sub>2</sub>-CrBr<sub>3</sub>-CrPS<sub>4</sub> heterostructures. Circularly polarized magneto-photoluminescence reveals robust nonvolatile valley polarization in WSe<sub>2</sub>-CrBr<sub>3</sub> with a pronounced low-field hysteresis tracking CrBr<sub>3</sub> magnetization. Spectroscopy and calculations indicate that spin-selective interfacial charge transfer and orbital hybridization enhance the proximity exchange field and valley Zeeman splitting. Introducing antiferromagnetic (AFM) CrPS<sub>4</sub> weakens the degree of circular polarization modulation and broadens the low-field valley polarization reversal, consistent with an interfacial AFM/FM exchange pinning scenario. These results show that interfacial magnetic engineering can tailor proximity-induced valley responses in 2D heterostructures.