Asymmetric Spin Gap Opening of Graphene on Cubic Boron Nitride (111) Substrate

Graphene grown on cubic BN (111) is studied using the first-principles method based on density functional theory. Results of our calculations reveal that spin polarized surface states break the equivalence of the A and B sublattices and lead to spin polarized graphene bands with finite energy gaps. As a result, spin polarized carriers can be generated by shifting the Fermi-level inside the band gap of minority (majority) spin but inside the conduction (valence) band of majority (minority) spin. The spin state of the injected electrons can be manipulated by an external electric field alone.