Switchable valley splitting by external electric field effect in graphene/CrI3 heterostructures

Abstract

Achieving and controlling valley splitting is a core issue for valleytronics applications. Conventionally, valley splitting was achieved by applying an external magnetic field or structural manipulation. However, this approach is less efficient. Here, we explored single layer and bilayer graphene on CrI3 (g-CrI3 and 2g-CrI3) heterostructures to induce valley splitting. In g-CrI3, we found a valley splitting with the majority gap difference of Δ1↑ − Δ2↑ = 44 meV. Even in 2g-CrI3 system, we also found valley splitting of Δ1↑ − Δ2↑ = 21 meV. Moreover, we also investigated the electric field effect on valley splitting. In both systems, we observed that valley splitting could be switched in the majority spin band. For instance, the sign of gap difference at ±K changed from Δ1↑ > Δ2↑ at zero field to Δ1↑