Tuning Spin Valley Coupling via Strain-Amplified Magnetic Proximity in Fe₃GaTe₂/WS₂ Heterostructures

The magnetic proximity effect (MPE) allows nonmagnetic materials to acquire magnetic properties via interfacial exchange, providing a route to manipulate spin and valley degrees of freedom in 2D heterostructures. However, MPE is typically limited by weak interfacial coupling, constraining the control of valley polarization and excitonic states in high-performance valleytronic devices. Here, we demonstrate that the MPE in the Fe₃GaTe₂/WS₂ heterostructure is effectively tuned as strain from a gold grating substrate enhances the interlayer coupling. The enhanced interlayer coupling promotes spin-dependent charge transfer in the MPE process, driving a pronounced longitudinal expansion of the WS₂ exciton valley polarization hysteresis loop and achieving a substantial modulation amplitude within the ±1 T magnetic field range. Simultaneously, the strain-enhanced MPE induces a pronouncedly enhanced Zeeman splitting, driving a giant Landé g-factor of WS₂ excitons up to -30. First-principles calculations attribute these effects to strain-induced band-structure reconfiguration and enhanced interlayer charge transfer. Our findings establish strain engineering as a powerful and precise approach to control the MPE, opening new avenues for advanced spin-valleytronic applications and next-generation low-dimensional quantum devices.