Symmetry of Superconductivity in Fullerides by Repulsive Interaction Model

A repulsive interaction model for superconductivity (SC) in fullerides is studied using a second-order perturbation theory with respect to Coulomb repulsion. With the purely repulsive interaction, Tg and Eg pairs are the most stable in bcc and fcc lattices, respectively. In addition to anisotropic SC pairs, the s-wave (Ag) pair can also be formed in both lattice models. Multiple Fermi surfaces in fullerides stabilize the Ag pairs. We propose that the cooperation between Coulomb repulsion and electron-phonon interaction is responsible for the high Tc