Correlation functions in the three-chain Hubbard ladder

TL;DR

This paper investigates the correlation functions in a three-chain Hubbard ladder to understand the dominance of superconducting correlations over magnetic ones, revealing that spin gaps can promote superconductivity.

Contribution

It provides a bosonization-based analysis of the doped three-chain Hubbard model, highlighting the dominance of singlet superconducting pairing due to spin gaps.

Findings

Singlet superconducting pairing is dominant across the central and edge chains.

Intra-edge spin density wave correlation is subdominant, reflecting a gapless mode.

Multiple spin modes with gaps can still support dominant superconductivity.

Abstract

In order to check whether odd-numbered Tomonaga-Luttinger ladders are dominated by antiferromagnetic correlations associated with gapless spin excitations, correlation functions of the doped three-chain Hubbard model are obtained with the bosonization at the renormalization-group fixed point. The correlation of the singlet superconducting pairing across the central and edge chains is found to be dominant, reflecting two gapful spin modes, while the intra-edge spin density wave correlation, reflecting the gapless mode, is only subdominant. This implies that, when there are multiple spin modes, a dominant superconductivity can arise from the presence of {\it some} spin gap(s) despite the coexistence of power-law correlated spins.