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

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