Coupled-layer analysis of the pair potential and the quasiparticle spectrum of superconducting cuprates

Abstract

A model is proposed which adapts BCS theory to describe the nontrivial layering present in the high-temperature superconducting cuprates. Starting from a few basic hypotheses, including that of weakly coupled CuO2 and non-CuO2 metallic layers, the ground-state wave function, Hamiltonian, pair potential, quasiparticle spectrum, and self-consistency condition are derived. A striking difference from the isotropic, homogeneous BCS case is the existence of at least two branches in the quasiparticle spectrum, one with a ‘‘low gap’’ and the other with a ‘‘high gap.’’ Unlike the temperature dependence of the pair potential, the temperature dependences of both spectral gaps are quite different from the homogeneous BCS result. Various implications of this model for measurements are described. Both low-energy features and features higher than the usual gap are related to the specific layered structures found in different cuprates.

Source-reported materials — not catalogue approval

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