Pairing mechanisms in high-Tcsuperconductors

Abstract

We study the electronic structure of Cu-O high-$T_c$ superconductors using a tight-binding Hamiltonian with strong intra-atomic and interatomic Coulomb repulsion. We assume that only $\mathrm{Cu}\left({3d}_{x^2-y^2}\right)$ and $\mathrm{O}\left({2p}_x\right)$ and $\mathrm{O}\left({2p}_y\right)$ orbitals are relevant. We solve finite clusters exactly and use a cell approximation to show that the basic assumptions together with quasidegeneracy of $p$ and $d$ energies leads to attractive interactions between holes in the ceramic superconductors.