SUPERCONDUCTING PAIRING INTERACTIONS AMONG QUASI-PARTICLES IN THE OXYGEN ORBITALS OF CUO2 PLANES

We discuss effective interactions between p-like quasiparticles present in CuO2 planes of the copper oxide superconductors. To do this, we have eliminated the d-p hybridization with the help of canonical transformation. The main effect of the d-p hybridization is the proximity in the vicinity of the M point of antibonding bands which, for small doping, are crossed by the Fermi level. Our analysis of the momentum dependence of effective interactions shows that there are definitively attractive contributions on the whole Fermi surface. Any averaging procedure reduces the number of channels possible for superconductivity and demonstrates the dominant role of bonding p-like quasiparticles in the formation of phonon-free Cooper pairs.