Ferromagnetism and valley polarization in Janus single-layer VSCl

Abstract

Two-dimensional ferromagnetic semiconductors have received extensive attention due to their promising application for valleytronics along with the opportunity to realize spontaneous valley polarization. Herein, by means of the first-principles calculations, we design a two-dimensional ferromagnetic semiconductor single-layer VSCl with the direct band gap is 0.88 eV, and magnetic moment is 2 μB per unit. The Curie temperature of single-layer VSCl is estimated to be 125 K based on the mean field approximation. In addition, the ferromagnetism can be further improved by adopting moderate tensile strain. Importantly, the intrinsic breaking of time and spatial inversion symmetry leads to the spontaneous valley polarization in single-layer VSCl. The corresponding valley polarization energy is about 57.8 meV, which is sizeable enough for practical operations. Our findings provide a candidate material for realizing the potential application of two-dimensional valleytronic devices.