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 heterostructures and investigated proximity effects on 2D magnetism. Through reflective magnetic circular dichroism, we have observed a temperature-dependent modulation of magnetic order in the heterostructure. For temperatures above 40K , WSe2-covered Fe3GeTe2 exhibits a larger coercive field than that observed in bare Fe3GeTe2, accompanied by a noticeable enhancement of the Curie temperature by 21K . 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<20K ), 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.