Enhancement of pairing in a boson-fermion model for coupled ladders

TL;DR

This study investigates how generalized Andreev couplings in a coupled ladder model enhance long-distance pairing correlations, influenced by Coulomb repulsion, with implications for strongly correlated systems.

Contribution

It introduces a numerical analysis of a boson-fermion coupled ladder model showing pairing enhancement due to generalized Andreev couplings and Coulomb interactions.

Findings

Long-distance pairing correlations are enhanced by both types of couplings.

Pair splitting into electrons on neighboring chains yields a larger effect near quarter filling.

Coulomb repulsion influences the competition between pairing and charge order.

Abstract

Motivated by the presence of various charge inhomogeneities in strongly correlated systems of coupled ladders, a model of spatially separated bosonic and fermionic degrees of freedom is numerically studied. In this model, bosonic chains are connected to fermionic chains by two types of generalized Andreev couplings. It is shown that for both types of couplings the long-distance pairing correlations are enhanced. Near quarter filling, this effect is much larger for the splitting of a pair in electrons which go to the two neighboring fermionic chains than for a pair hopping process. It is argued that the pairing enhancement is a result of the nearest neighbor Coulomb repulsion which tunes the competition between pairing and charge ordering.