A Theoretical Analysis of Superconducting Pairing in Correlated Metallic Systems

TL;DR

This paper presents a theoretical study of superconducting pairing in correlated metallic systems, highlighting the emergence of a two-gap structure influenced by Coulomb correlations and phonon interactions.

Contribution

It introduces a variational approach incorporating Coulomb correlations via Gutzwiller projection in a 3D system, revealing a novel two-gap-like superconducting structure.

Findings

Two-gap-like superconducting structure observed

Coulomb correlation strength modulates pairing gaps

Application to a simple cubic lattice system

Abstract

We have introduced a Coulomb correlated normal state to study the superconducting pairing with a Fermi liquid like normal phase background in a 3 dimensional system. The role of the Coulomb correlation has been actively incorporated by means of Gutzwiller projection scheme, in the presence of phonon mediated attractive electron-electron interaction throughout the entire regime of its applicability. We variationally modulate the Coulomb correlation strength from the weak to the strong regime in our calculational procedure. The main highlight of our results is the appearance of a '2-gap-like' structure in the superconducting phase, arising out of the two-body interacting matrix elements, calculated in the presence of the active Coulomb correlation. We have made use of the 'two-square well model' potential to evaluate the superconducting pairing gaps at zero temperature. Our Calculational scheme has been applied to a simple cubic lattice system for a physical realization. All the consequences are elaborated and discussed.