Tunable valley states in two-dimensional ScBr2

Effective manipulation of valley degrees of freedom can offer significant opportunities for both fundamental research and practical applications. In this work, based on the first-principles calculations, we, respectively, studied the modulation of the valley states of the two-dimensional (2D) ferrovalley material ScBr2 in its bilayers and multiferroic heterostructures. The sliding ferroelectricity is found in ScBr2 bilayers, and the ferroelectric polarization is coupled with valley polarization, which can enable the switching of layer-polarization anomalous Hall effect. The switching of magnetic ground states can also be achieved through layer sliding. On the other hand, the reversal of the ferroelectric polarization of Ga2S3 in the ScBr2/Ga2S3 heterojunction can induce a semiconductor to half-metal phase transition, thereby enabling control of the anomalous valley Hall effect for “on” and “off” states. Our work provides two effective ways to manipulate the valley states in 2D materials.