Effective pairing theory for strongly correlated d-wave superconductors

TL;DR

This paper develops a simple pairing theory for strongly correlated d-wave superconductors with moderate disorder, incorporating strong correlations and inhomogeneities, and shows it aligns with more complex methods.

Contribution

It introduces a pairing theory that accounts for strong correlations and disorder effects in d-wave superconductors, matching results from advanced Gutzwiller-based calculations.

Findings

Normal states capture disorder and correlation effects accurately

The pairing results align with Gutzwiller-augmented Bogoliubov-de Gennes analysis

Theory explains impurity insensitivity in d-wave superconductors

Abstract

Motivated by recent proposals of correlation induced insensitivity of d-wave superconductors to impurities, we develop a simple pairing theory for these systems for up to a moderate strength of disorder. Our description implements the key ideas of Anderson, originally proposed for disordered s-wave superconductors, but in addition takes care of the inherent strong electronic repulsion in these compounds, as well as disorder induced inhomogeneities. We first obtain the self-consistent one-particle states, that capture the effects of disorder exactly, and strong correlations using Gutzwiller approximation. These `normal states', representing the interplay of strong correlations and disorder, when coupled through pairing attractions following the path of Bardeen-Cooper-Schrieffer (BCS), produce results nearly identical to those from a more sophisticated Gutzwiller augmented Bogoliubov-de Gennes analysis.