Superconductivity of metallic graphene

Abstract

It has been found that the states at the level of the Fermi energy of undoped graphene sheet reduces to zero, making it difficult for the Cooper pairing of such a system to exist in its superconductive state. Instead, T-graphene, having physical properties close to graphene, exhibits a metallic behavior which means the existence of the available states for electrons near to Fermi level. For this two-dimensional metallic system, the gap equation of the s-wave superconductive state is derived based on the Bogoliubov de Gennes equation within the attractive Hubbard model. Using the gap equation, a nonzero critical temperature, Tc, is found for different amounts of electron–electron interaction, U. Tc has higher values when the system possesses electronic half band-filling, whereas the reverse is true when the system does not have half band-filling. However, close to band edges, Tc vanishes when U becomes small enough.