Manipulation of valley splitting for the WSe2/NiCl2 heterostructure by adjusting the interlayer spacing and constructing a NiCl2/WSe2/NiCl2 heterojunction

Abstract The electronic band structure and valley splitting of the WSe 2 /NiCl 2 heterostructure have been investigated by density functional theory and Berry curvature calculations. We demonstrate that the valley polarization of monolayer WSe 2 is induced due to the magnetic proximity effect caused by the single layer of ferromagnetic NiCl 2 . The magnitude of valley splitting depends on the stacking configurations of WSe 2 /NiCl 2 , and the maximum value of valley splitting reaches −11.87 meV. Large valley splitting can be achieved by adjusting the layer spacing and constructing a NiCl 2 /WSe 2 /NiCl 2 heterojunction with Ni spins arranged in parallel between two NiCl 2 sheets. The valley-contrasting Berry curvature between the K and K ′ valleys suggests that the WSe 2 /NiCl 2 -based heterostructure could potentially be used as a valleytronic device to realize the valley-polarized anomalous Hall effect as both spin and valley filter.