Controllable dual-polarization valley physics in the strain-engineered 2D monolayer of VC2N4

Abstract

Valley-related physics has garnered significant attention in fundamental studies and cutting-edge information technologies. However, such valleytronic materials have rarely been reported and suffer from in-plane magnetization. Herein, based on first-principles calculations and tight-binding model analysis, we identify the existence of intrinsic valley-contrasting physics in bipolar ferromagnetic monolayer VC₂N₄ with robust perpendicular magnetic anisotropy behavior. Valley polarization arises spontaneously due to the simultaneous presence of broken space- and time-inversion symmetries. Interestingly, valley polarization is remarkably observed in both the valence and conduction bands around the K/K′ valley due to large spin splitting, indicating rare dual-polarization valley features, which is advantageous for achieving the captivating anomalous valley Hall effect relied on the valley-contrasting Berry curvature. Remarkably, the valley polarization can be switched on/off by applying a moderate biaxial strain. Our work provides a competitive candidate for exploring valley-dependent physics and its applications in valleytronics.