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

Abstract

The manipulation of the 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 the 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 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 be modulated through biaxial strain. Interestingly, bandgap opening behavior is observed when compressive strains are 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.