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

Abstract

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 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 on proximity coupling may shed light on the design of future spintronic and memory devices based on 2D magnetic heterostructures.