Composite operators for BCS Superconductor

TL;DR

This paper introduces a generalized composite operator for BCS superconductors, extending the concept of Cooper pairs to include various pairing symmetries in a 2D t-J model.

Contribution

It presents a new form of composite operator that generalizes Cooper pairs, applicable to different pairing symmetries in superconductors.

Findings

Defined composite operators for d_{x^2-y^2}, d_{xy}, and p-wave symmetries

Extended the composite operator framework to a 2D t-J model

Provided examples illustrating the applicability of the new operators

Abstract

The new form of the composite operator generalizing the Cooper pairs for a BCS superconductor is introduced. The approach is similar to the derivation of the composite operator of the odd - frequency superconductors. The examples of the $d_{x^2-y^2}-,~d_{xy}-$ and $p-$ wave composite operators for a 2D $t-J$ model are given.