Phase-Dependent Magnetic Proximity Modulations on Valley Polarization and Splitting.

Proximate-induced magnetic interactions present a promising strategy for precise manipulation of valley degrees of freedom. Taking advantage of the splendid valleytronic platform of transition metal dichalcogenides, magnetic two-dimensional VSe ₂ with different phases are introduced to intervene in the spin of electrons and modulate their valleytronic properties. When constructing the heterostructures, 1T-VSe ₂ /WX ₂ (X = S and Se) showcases significant improvement in the valley polarizations at room temperature, while 2H-VSe ₂ /WX ₂ exhibits superior performance at low temperatures and demonstrates heightened sensitivity to the external magnetic field. Simultaneously, considerable valley splitting with a large g _eff factor up to -29.0 is observed in 2H-VSe ₂ /WS ₂ , while it is negligible in 1T-VSe ₂ /WX ₂ . First-principles calculations reveal a phase-dependent magnetic proximity mechanism on the valleytronic modulations, which is dominated by interfacial charge transfer in 1T-VSe ₂ /WX ₂ and the proximity exchange field in 2H-VSe ₂ /WX ₂ heterostructures. The effective control over valley degrees of freedom will bridge the valleytronic physics and devices, rendering enormous potential in the field of valley quantum applications.