Tunable valley splitting and anomalous valley Hall effect in VTe2/Ga2S3 heterostructures

Abstract

The modulation of valley splitting is not only of fundamental interest but is also crucial to valleytronics. Generally, valley splitting stems from spin–orbit coupling and the absence of time-reversal symmetry, which are irreversible. In this work, we proposed another approach to achieve static and reversible valley splitting via an antiferromagnetic/ferroelectric heterostructure. The heterostructure is composed of an antiferromagnetic VTe₂ bilayer deposited on a ferroelectric substrate (Ga₂S₃). The electric field of the ferroelectric substrate lifts the valley degeneracy, leading to valley splitting, which is dependent on the intensity of the electric field. With the increase of substrate thickness, the valley splitting of the VTe₂ bilayer can attain 132 meV. More interestingly, both the Berry curvature and the carrier spin are reversed by switching the ferroelectric direction of the substrate, resulting in tunable anomalous valley Hall effect. Our computational results offer a promising strategy for all-electrical reading and writing memory devices.