Superconductivity of metallic graphene

It has been found that the states at the level of the Fermi energ y 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, ������������, is found for different amounts of electron-electron interaction, ������. ������������has higher values when the system possesses electronic ha l f band-filling, whereas the reverse is true when the system does not have ha l f band-filling. However, close to band edges, ������������vanishes when ������becomes sma l l enough.

Automated summary

It has been found that undoped graphene sheet has zero states at the Fermi energy level, making it difficult for Cooper pairing to occur in the superconductive state. However, T-graphene, with physical properties similar to graphene, exhibits metallic behavior and has available electron states near the Fermi level. The gap equation for the s-wave superconductive state is derived based on the attractive Hubbard model and the Bogoliubov de Gennes equation for this two-dimensional metallic system. It is found that a nonzero critical temperature, τ, exists for different levels of electron-electron interaction, ǫ. τ has higher values when the system has electronic half band-filling, but decreases when the system does not have half band-filling. However, τ vanishes when ǫ becomes small enough near the band edges.