Superconductivity generated by coupling to a Cooperon in a 2-dimensional array of 4-leg Hubbard ladders

TL;DR

This paper proposes a mechanism for superconductivity in a 2D array of four-leg Hubbard ladders, where coupling to a Cooperon excitation induces an attractive interaction leading to superconductivity, supported by both weak and strong coupling analyses.

Contribution

It introduces a low-energy effective model showing how Cooperon excitations can generate superconductivity in ladder arrays, bridging weak and strong coupling regimes.

Findings

Effective model with a truncated Fermi surface and Cooperon excitation.

Attractive interaction in the Cooper channel induced by virtual scattering.

Features consistent with strong coupling t-J model results near half-filling.

Abstract

Starting from an array of four-leg Hubbard ladders weakly doped away from half-filling and weakly coupled by inter-ladder tunneling, we derive an effective low energy model which contains a partially truncated Fermi surface and a well defined Cooperon excitation formed by a bound pair of holes. An attractive interaction in the Cooper channel is generated on the Fermi surface through virtual scattering into the Cooperon state. Although the model is derived in the weak coupling limit of a four-leg ladder array, an examination of exact results on finite clusters for the strong coupling t-J model suggests the essential features are also present for a strong coupling Hubbard model on a square lattice near half-filling.