Coulomb Correlations and Pseudo-gap Effects in a Pre-formed Pair Model for the Cuprates

TL;DR

This paper investigates how Coulomb correlations influence pseudo-gap phenomena and thermodynamic properties in pre-formed pair models of cuprate superconductors, highlighting the role of charge fluctuations and plasmon effects.

Contribution

It extends existing pre-formed pair models by incorporating Coulomb correlation effects, providing a more comprehensive understanding of pseudo-gap behavior in cuprates.

Findings

Coulomb interactions significantly alter collective modes.

Charge fluctuations impact the pseudo-gap and critical temperature.

Thermodynamic quantities are affected by plasmon effects.

Abstract

We extend previous work on pre-formed pair models of superconductivity to incorporate Coulomb correlation effects. For neutral systems, these models have provided a useful scheme which interpolates between BCS and Bose Einstein condensation with increasing coupling and thereby describes some aspects of pseudo-gap phenomena. However, charge fluctuations (via the plasmon, $\omega_p$) significantly modify the collective modes and therefore the interpolation behavior. We discuss the resulting behavior of the pseudo-gap and thermodynamic quantities such as $T_c$, $\chi$ and $C_v$ as a function of $\omega_p$.