Pseudogap and its influence on normal and superconducting states of cuprates

A model incorporating simultaneous superconducting and Jahn-Teller-like lattice instabilities has been studied in detail to estimate the nature of coupling and interplay between them in cuprates. It is found that a pseudogap develops due to lattice distortion in Cu-O layer and interferes destructively with superconductivity. The phase diagram is obtained in the temperature-filling plane at different values of the parameters of the model. The superconducting instability is strongest for the regime of filling where the van Hove singularity in the 2D density of states is close to the chemical potential. The pseudogap, developed in the distorted phase, is a function of temperature via the temperature dependence of the distortion itself. Transport properties, namely resistivity and thermopower are found to be strongly dependent on the variations of the pseudogap. (C) 2001 Published by Elsevier Science B.V.