Magnetic proximity effect and tunable valley splitting in 2D CrGeTe3/MTe2 (M = Mo, W) van der Waals heterostructures

Proximity-induced magnetic exchange interactions offer a novel approach to manipulate the valley degree of freedom (DOF) in nonmagnetic monolayers without external magnetic fields. Transition metal dichalcogenides (TMDs) serve as an ideal platform for valleytronics research. Here, by introducing a two-dimensional (2D) magnetic substrate, chromium germanium telluride (CrGeTe 3 ), we demonstrate effective control over the spin and valley properties of CrGeTe 3 /MTe 2 (M = Mo, W) van der Waals (vdW) heterostructures. Our first-principles calculations and model Hamiltonian analysis reveal that the magnetic proximity effect (MPE) induces valley splitting and polarization in monolayer MoTe 2 and WTe 2 through the synergistic action of spin-orbit coupling (SOC) and proximity exchange interactions. Further investigation shows that valley splitting in these heterostructures is highly sensitive to the overlap between the atomic projection positions of TMDs and the magnetic Cr atoms, and can be continuously adjusted by varying the magnetization of CrGeTe 3 . Additionally, normal strain and experimentally accessible electric fields can effectively modulate the proximity exchange coupling, thus enabling extensive tunability of valley splitting. These controllable manipulations of the valley DOF through external stimuli mark a significant advancement in valleytronics, paving the way for next-generation electronic devices with enhanced performance and novel functionalities. • We identified an optimal stacking configuration that is universally applicable to similar systems. • Introduced a model to extract the actual proximity exchange parameters. • Explained the cosine-like relationship between valley splitting and magnetization direction. • Achieved the modulation of valley splitting through normal strain and external electric fields.