A pairing mechanism in which attractive intersite interaction arises from the highly correlated electronic structure of the superconducting ceramics has been recently proposed by Balseiro and collaborators. This model is studied here in the limit of infinite Coulomb repulsion (i.e., Ũ→∞) by employing standard decoupling techniques of the relevant Green’s functions. We derive the critical temperature $T_c$ and the superconducting gap $E_g$ as a function of the relevant parameters of the model. The ratio $E_g$/$T_c$ obtained is not a constant and is different from the universal value of BCS superconductivity.

• Received 20 June 1989

DOI:https://doi.org/10.1103/PhysRevB.40.9288