Stacking-dependent tunable valley splitting in Janus SMoSiN2-based van der Waals heterostructure

Using the first principles calculation, we explore the modulation of valley-related properties of two-dimensional (2D) Janus SMoSiN2 monolayer by constructing van der Waals (vdW) heterostructure with the ferromagnet CrCl3 monolayer. The monolayered SMoSiN2 possesses excellent stability and direct bandgap at the K/K′ valley, making it a promising candidate for valleytronic semiconductor. The ferromagnet CrCl3 substrate induces a sizable valley splitting via proximity coupling. The valley-contrasting property of the top-stacking is significantly tunable by both in-plane sliding and vertical strain engineering, leading to extraordinary tunability of valley splitting in the range 1.6–9.4 meV. In contrast, the valley-contrasting property of the bottom-stacking is comparably robust due to the screen effect originating from the outmost N sublayer to reduce the proximity interaction. Our investigation reveals that the stacking order is a degree of freedom to manipulate the valley-related properties of various vdW heterostructures, facilitating the achievement of versatile valley-contrasting properties.