One-Dimensional Electron Liquid in an Antiferromagnetic Environment: Spin Gap from Magnetic Correlations

TL;DR

This paper investigates how magnetic correlations in an antiferromagnetic environment induce a spin gap in a one-dimensional electron liquid, with potential relevance to cuprate striped phases.

Contribution

It demonstrates, via renormalization group analysis, that magnetic correlations can open a spin gap in 1D electron liquids coupled to antiferromagnetic ladders, regardless of the ladder's gap status.

Findings

Magnetic correlations induce a spin gap in the electron liquid.

The effect is enhanced by electron-electron repulsion.

The spin gap formation is insensitive to the sign of the exchange interaction.

Abstract

We study a one-dimensional electron liquid coupled by a weak spin-exchange interaction to an antiferromagnetic spin-S ladder with n legs. A perturbative renormalization group analysis in the semiclassical limit reveals the opening of a spin gap, driven by the local magnetic correlations on the ladder. The effect, which we argue is present for any gapful ladder or gapless ladder with $nS\gg 1$, is enhanced by the repulsive interaction among the conduction electrons but is insensitive to the sign of the spin exchange interaction with the ladder. Possible implications for the striped phases of the cuprates are discussed.