Metal-insulator transition and the anomalous Hall effect in the layered magnetic materials VS₂ and VSe₂

We investigated the electronic structure of the layered transition-metal dichalcogenides VS₂ and VSe₂ by first-principles calculations. Both compounds exhibit metal-insulator transitions when crossing over from the bulk to the two-dimensional monolayer. In the monolayer limit, the Coulomb interaction is enhanced due to the dimension reduction, leading to the insulating state. Moreover, these monolayers are found to be ferromagnetic, supplying excellent candidates for ferromagnetic insulators. When increasing the thickness, the few-layer structure turns metallic and presents large anomalous Hall conductivity (∼100 S/cm), which oscillates with respect to the thickness due to the size effect. Our findings presents profound materials, such as ferromagnetic insulators and anomalous Hall ferromagnets, for the spintronic application.