First-principles investigation of bilayer graphene with intercalated C, N or O atoms.

We apply first-principles calculations to investigate the structural, electronic and magnetic properties of the bilayer graphene, into which C, N or O atoms are intercalated. The inserted atoms initially set at the middle of the bilayer interval will finally be adsorbed to one graphene layer, resulting in the difference of electrostatic potential between the two graphene layers and then an opening of the energy gap filled with impurity states. Extended or quasilocalized states around the Fermi level introduced by the intercalated atoms induce the itinerant Stoner magnetism in C- and N-intercalated systems. The magnetic moment in the N-intercalated system is mainly contributed by the N atom, while in the C-intercalated system, besides the foreign intercalated C atom, host carbon atoms of the bilayer graphene also become magnetic, with the magnetization distribution showing threefold symmetry. Also, charge transfer from bilayer graphene to the intercalated N or O atoms results in the Fermi level shifting downward to the valence band and then the metallic behavior of the system.