Tunable valley polarization and high Curie temperature in two-dimensional GdF2/WSe2 van der Waals heterojunctions†

Abstract

Two-dimensional (2D) van der Waals (vdW) heterojunctions have potential applications in spintronic devices owing to their unique electronic structure and properties. The 2D ferromagnetic material GdF₂, formed by the rare earth element (Gd) with 4f electrons and fluorine, exhibits spontaneous valley polarization, perpendicular magnetic anisotropy and other excellent properties. Monolayer WSe₂ has a similar structure to monolayer GdF₂ and can be used to construct a vdW heterojunction. The heterojunction not only retains the original excellent properties but also generates new physical properties due to interfacial charge transfer and coupling. Therefore, this work investigates the electronic structure, magnetic anisotropy energy and Curie temperature (T_c) of the GdF₂/WSe₂ heterojunction. The GdF₂/WSe₂ heterojunction exhibits spontaneous valley polarization and can be modulated by biaxial strain. Additionally, valley polarization can be regulated by applying an external electric field and changing interface spacing. These results indicate that the GdF₂/WSe₂ heterojunction can be used as a promising platform for the study of spintronic and valleytronic devices and provide ideas for the development of new electronic devices.