Stability of the superconducting \({d_{{x^2} - {y^2}}}\) phase in high-Tc superconductors with respect to the intersite coulomb repulsion of holes at oxygen

Abstract

It has been shown that, because of the two-orbital character of the subsystem of holes located at oxygen sites and the spatial separation of this subsystem from that of spins at copper ions, the superconducting phase in high-T_c superconductors is stable with respect to the strong Coulomb repulsion of holes located at nearestneighbor oxygen sites if the order parameter has the \({d_{{x^2} - {y^2}}}\) symmetry. This effect is due to the symmetry characteristics of the Coulomb potential, owing to which the equation determining the Cooper pairing in the \({d_{{x^2} - {y^2}}}\) channel does not include this potential.