Intrinsic valley polarization and manipulation by interfacial coupling in two-dimensional GdIBr/In2Se3 van der Waals multiferroic heterojunction

Abstract

The manipulation of valley degree of freedom provides a new paradigm for applications in electronic devices. In this work, using first-principles density functional theory, a two-dimensional (2D) GdIBr/In2Se3 van der Waals (vdW) heterojunction consisting of ferromagnetic GdIBr and ferroelectric In2Se3 is proposed. The valley polarization of GdIBr at K and K' points is regulated by the magnetoelectric coupling effect between ferromagnetic and ferroelectric materials. The valley polarization of all heterojunctions with different stacking patterns is larger than that of the monolayer GdIBr. The interfacial charge transfer, valley polarization origin, magnetic properties and Curie temperature of the heterojunction are analyzed. In addition, the valley polarization of the GdIBr/In2Se3 heterojunction can also be modulated by biaxial strain. Interestingly, the bandgap opening behavior is observed when compressive strains is applied to the heterojunction, and the bandgap size is correlated with the strain coefficient. These results all suggest that the GdIBr/In2Se3 vdW heterojunction is a promising valleytronic material with potential applications for novel electronic devices.