Copper-Oxide Superconductors as Mixed-Valence Heavy Fermions: Spin-Fluctuation Mechanism of Superconductivity

Abstract

It is proposed that the physics of high-T_c superconductors with a CuO₂ network can be understood in a way parallel to that of heavy-fermion superconductors where the spin fluctuations play an important role. On the basis of a periodic Wolff model with aspects specific to copper oxides, it is shown that the charge carriers are the p-like holes when the antibonding band is filled less than half. It is also shown that these charge carriers form relatively heavy Fermi liquid with an effective bandwidth T₀∼10³ K, which is consistent with experiments.