Superconductivity near Charge Transfer Instability in CuO₂ Structure

抄録

The possible symmetries of superconductivity is studied on a system near charge transfer instability in CuO₂ layer structure for a case where the Cu sites do not have magnetic moment. This case corresponds either to ignore the existence of magnetic moments in actual high T_c Cu-oxides by focusing only on charge fluctuations or to consider the ground state configurations of d⁸ or d¹⁰ at the Cu-sites. By deriving effective interaction processes, which become important near the charge transfer instability, the critical temperatures have been estimated as a function of the doping rate, δ, based on weak-coupling approximation. It is seen that they have characteristic δ-dependence depending on symmetry.