Effects of a weak disorder on two coupled Hubbard chains

TL;DR

This paper investigates how weak nonmagnetic disorder influences the phases of two coupled Hubbard chains, revealing that disorder can both enhance and suppress certain superconducting states depending on interaction types.

Contribution

It provides a detailed analysis of disorder effects on coupled fermionic chains, highlighting the contrasting behaviors of superconducting phases with and without spin.

Findings

Disorder increases localization in spinless chains with repulsive interactions.

Disorder stabilizes s-wave superconductivity in spinless chains with attractive interactions.

Disorder destroys the d-wave phase in spinful chains with repulsive interactions.

Abstract

We consider the effect of weak nonmagnetic disorder on two chains of interacting fermions (with and without spins) coupled by interchain hopping. For the spinless case, interchain hopping increases localization for repulsive interactions but {\it stabilizes} the s-wave superconducting phase for attractive interactions. For the case with spin, the d-wave phase arising from purely repulsive interactions in the clean system is destroyed by an infinitesimal disorder while for attractive interactions, the s-wave superconductivity is more resistant to disorder than in the one-chain case.