Theory of Superconductivity in Graphite Intercalation Compounds

TL;DR

This paper demonstrates that a successful model for superconductivity in graphite intercalation compounds can accurately predict transition temperatures across various compounds, and suggests potential for higher Tc values beyond 10 K.

Contribution

It extends a previously successful model to new compounds, showing its robustness and predictive power for superconductivity in graphite intercalation compounds.

Findings

Model reproduces observed Tc in CaC6 and YbC6

Predicts Tc can be enhanced beyond 10 K

Comparison with density functional theory highlights advantages

Abstract

On the basis of the model that was successfully applied to KC8, RbC8, and CsC8 in 1982, we have calculated the superconducting transition temperature Tc for CaC6 and YbC6 to find that the same model reproduces the observed Tc in those compounds as well, indicating that it is a standard model for superconductivity in the graphite intercalation compounds with Tc ranging over three orders of magnitude. Further enhancement of Tc well beyond 10 K is also predicted. The present method for calculating Tc from first principles is compared with that in the density functional theory for superconductors, with paying attention to the feature of determining Tc without resort to the concept of the Coulomb pseudopotential.