Tailoring coercive fields and the Curie temperature via proximity coupling in WSe₂/Fe₃GeTe₂ van der Waals heterostructures

Hybrid structures consisting of two-dimensional (2D) magnets and semiconductors have exhibited extensive functionalities in spintronics and opto-spintronics. In this work, we have fabricated WSe₂/Fe₃GeTe₂ van der Waals (vdW) heterostructures and investigated the proximity effects on 2D magnetism. Through reflective magnetic circular dichroism (RMCD), we have observed a temperature-dependent modulation of magnetic order in the heterostructure. For temperatures above $40$ K, WSe₂-covered Fe₃GeTe₂ exhibits a larger coercive field than that observed in bare Fe₃GeTe₂, accompanied by a noticeable enhancement of the Curie temperature by $21$ K. This strengthening suggests an increase in magnetic anisotropy in the interfacial Fe₃GeTe₂ layer, which can be attributed to the spin-orbit coupling (SOC) proximity effect induced by the adjacent WSe₂ layers. However, at much lower temperatures ($T<20$ K), a non-monotonic modification of the coercive field is observed, showing both reduction and enhancement, which depends on the thickness of the WSe₂ and Fe₃GeTe₂ layers. Moreover, an unconventional two-step magnetization process emerges in the heterostructure, indicating the short-range nature of SOC proximity effects. Our findings revealing proximity effects on 2D magnetism may shed light on the design of future spintronic and memory devices based on 2D magnetic heterostructures.