Theoretical model study of dynamic ferromagnetic susceptibility in mono-layer graphene

We report here a microscopic theoretical study of dynamic ferromagnetic spin susceptibility of electrons for graphene systems, which deal with a tight-binding model Hamiltonian consisting of the hopping of electrons up to third-nearest-neighbors, impurity and substrate effects besides Coulomb interaction of electrons at A-and B- sub- lattices. The spin susceptibility involves four two-particle Green’s functions, which are calculated by Zubarev’s Green’s function technique. The up and down electron occupancies at A and B sub-lattices are computed numerically and self-consistently. The temperature dependent susceptibility shows a pronounced peak at Curie temperature for critical Coulomb interaction U c = 2.2t 1.