Non-uniform and anisotropic electric polarizability resulting in pronounced local repulsion minima in high-temperature superconductors

We demonstrate the dramatic effect of non-uniform, discrete electric polarizability in high-T_C superconductors on the spatial fluctuations of the short to medium range Coulomb interactions through a real-space semiclassical model. Although this is a general property, we concentrate on the cuprates as parent compounds, in which the charge carriers are primarily concentrated on the O sublattice. The anisotropic effective Cu-O bond polarization caused by charge transfer energy modulation and the O^2- atomic polarizability together generate a non-monotonic screened hole-hole Coulomb interaction at short distances that displays a local minimum at the in-plane second nearest neighbor O-O distance solely along the Cu-O bond direction. This is in accordance with the pseudogap phase anisotropy and the short coherence length observed in many high-T_C superconductors.