Band Gap Opening in Bilayer Graphene-CrCl3/CrBr3/CrI3 van der Waals Interfaces

We report experimental investigations of transport through bilayer graphene (BLG)/chromium trihalide (CrX3; X = Cl, Br, I) van der Waals interfaces. In all cases, a large charge transfer from BLG to CrX3 takes place (reaching densities in excess of 10(13) cm(-2)), and generates an electric field perpendicular to the interface that opens a band gap in BLG. We determine the gap from the activation energy of the conductivity and find excellent agreement with the latest theory accounting for the contribution of the sigma bands to the BLG dielectric susceptibility. We further show that for BLG/CrCl3 and BLG/CrBr3 the band gap can be extracted from the gate voltage dependence of the low-temperature conductivity, and use this finding to refine the gap dependence on the magnetic field. Our results allow a quantitative comparison of the electronic properties of BLG with theoretical predictions and indicate that electrons occupying the CrX3 conduction band are correlated.

Automated summary

We experimentally investigate the charge transfer and electric field effect at the interface of bilayer graphene and chromium trihalide. Our findings demonstrate the generation of a band gap in bilayer graphene due to charge transfer, and the gap size is determined by the conductivity and gate voltage dependence. The experimental results agree well with theoretical predictions and suggest the correlation of electrons in the chromium trihalide conduction band.