Pairing interaction in two-dimensionalCuO2

Abstract

We show that planar ${\mathrm{CuO}}_2$ clusters with strong repulsive Coulomb interactions can exhibit an effective attractive pairing interaction. This interaction arises from a disruption of the local lattice charge distribution produced when a hole is added and occurs for a wide range of parameter values, in the region where both the on-site Cu repulsion and the nearest-neighbor Cu-O repulsion are appreciable. A signature of this mechanism is that the occupation of Cu sites decreases as the system is doped. We suggest that this effective attractive interaction is responsible for high-$T_c$ superconductivity in oxides.