Electrically switching the valley polarization of 2D semiconductor

Controlling the valley degree of freedom in transition metal dichalcogenide(TMD) semiconductors is essential to the application of valleytronic devices. The strong magnetic coupling between monolayer TMD semiconductor WSe2 and few layer CrI3, a recently discovered 2D magnet, provides a novel approach for lifting the valley degeneracy and switching the valley polarization. In this talk we present our result on gate controlled valley polarization in CrI3/WSe2 heterostructures. Due to the short-range magnetic proximity interaction, WSe2 shows clear valley polarization controlled by the spin orientation of CrI3. We demonstrate that the magnetic coupling between WSe2 and CrI3 could be effectively tuned by gate voltage, allowing reversible and efficient electrical switching of the valley polarization in WSe2.