ANISOTROPIC SUPERCONDUCTIVITY IN THE EMERY MODEL

We have investigated anisotropic superconductivity originating from in tersite pairing between holes in nearest and next nearest neighboring sites in the Emery model. Strong local Coulomb correlations among hole s in copper orbitals have been taken into account within the Hubbard I approximation scheme. The superconducting transition temperature has been evaluated as a function of the hole concentration. It has been sh own that with the onset of superconductivity, pairing among oxygen-lik e quasiparticles in the mixed s-wave+d-wave channel plays the dominati ng role, being replaced by pairing in the extended s-wave channel for higher concentration of holes. Superconducting correlations are mostly effective for a rather narrow range of the model parameter values, cl ose to values derived from band structure calculations. Therefore, the coupling between a-wave and d-wave channels seems to be a general fea ture of superconductivity in CuO2 planes.