Prediction of the ferrovalley property with sizable valley splitting in Janus monolayer GdBrI

The exploitation of two-dimensional (2D) ferrovalley materials is of great significance in promoting the development of novel information storage devices, which is garnering increasing interest nowadays. However, the currently discovered 2D ferrovalley materials are very limited, and some of them still suffer from the drawback of small valley splitting, which seriously hinders their application in valleytronics. Herein, using first-principles calculations, we predict a promising 2D ferrovalley material, Janus monolayer GdBrI, which harbors sizable valley splitting and the anomalous valley Hall effect (AVHE). Monolayer GdBrI is a stable ferromagnetic semiconductor with an easy magnetization plane and magnetic transition temperature of 264.5 K. When the magnetization orientation is toward the z direction, valley polarization with a large splitting of 120.4 meV is achieved in the valence band due to the synergetic effect between the magnetic exchange interaction and spin-orbit coupling. The valley-contrasting Berry curvature gives rise to the AVHE in the monolayer. The magnitude of valley splitting can be continuously tuned by varying the magnetization orientation, biaxial strain and perpendicular electric field. These findings offer Janus monolayer GdBrI as a potential candidate for spintronic and valleytronic applications.