Valley polarization, magnetic anisotropy and Dzyaloshinskii-Moriya interaction of two-dimensional graphene/Janus 2H-VSeX (X = S, Te) heterostructures

Two-dimensional (2D) heterostructures based on graphene (Gr) and 2D magnetic materials have attracted much attention due to the unique properties, which have the potential applications in nanoelectronics, optoelectronics and spintronics. Here, the electronic structure and magnetic properties of 2D Gr/Janus 2H-VSeX (X = S, Te) (Gr/VSeX) heterostructures are investigated systematically by density functional theory. The Dirac cones of graphene in Gr/VSeX heterostructures open a band gap, where the valley splitting appears at K and K′ points by considering spin-orbit coupling effect. By comparing to Janus VSeTe monolayer, the valley splitting and Dzyaloshinskii-Moriya interaction (DMI) of Gr/VSeTe heterostructure are significantly enhanced. Meanwhile, the electronic structure and magnetic properties of Gr/VSeTe heterostructure can also be modulated by external electric field, interlayer distance and in-plane biaxial strain, where the in-plane biaxial strain effects on DMI is more pronounced. Moreover, the valley splitting of graphene (VSeTe) can be effectively enhanced by decreasing the interlayer distance of Gr/VSeTe heterostructure. These results show the potential applications of 2D magnetic heterostructures in nonoelectronics, spintronics and valleytronics.