Electronic and magnetic properties of graphene/fluorographene superlattices

On the basis of density functional theory calculations, the electronic and magnetic properties of graphene/fluorographene superlattices (GFSLs) are systematically investigated. Our calculations show that the electronic properties are both interface-orientation- and graphene-width-dependent. All armchair GFSLs (AGFSLs) are semiconducting with a band gap being graphene-width-dependent and exhibiting three distinct families of characteristics similar to that of armchair graphene nanoribbons. The zigzag GFSLs (ZGFSLs) with an extremely small graphene width are nonmagnetic and semiconducting. As the width of graphene increases, however, ZGFSLs become magnetic with the antiferromagnetic (AFM) state being their ground state. Our results also reveal that, if the graphene width is kept constant, the total energy differences between the non-spin-polarized (NSP) state and the AFM state and between the ferromagnetic (FM) state and the AFM are independent of the superlattice period. When the graphene width is large, the AFM and FM states are nearly degenerated as their total energy difference is less than 10 meV. In addition, our results also show that the strain can be practically used to tune the band gap of flat AGFSLs while the strain effect can be effectively shielded by the accordion structure of ZGFSLs.