First-principles study of a single-molecule magnet $Mn_{12}$ monolayer on the graphene surface.*

Electronic structures of single-molecule magnets $Mn_{12}$ on graphene surfaces are studied using spin-polarized density-functional theory. Charge transfer between molecule and graphene, densities of states, and magnetization are fully analyzed. We also report effects of various ligands and strain. Our results suggest that graphene can be p-doped upon $Mn_{12}$ adsorption, and the doping level is closely related to the choice of ligands in molecule. In addition, we find that the strain in graphene plays an important role in modulating the doping level.