Pairing and Density Correlations of Stripe Electrons in a Two-Dimensional Antiferromagnet

TL;DR

This paper models a one-dimensional electron stripe within a 2D antiferromagnetic insulator, revealing phases with enhanced density and pairing correlations influenced by stripe fluctuations and magnetic configurations.

Contribution

It introduces a low-energy sine-Gordon effective theory for stripe electrons coupled to antiferromagnetic order, analyzing its phases and correlation behaviors.

Findings

Identifies a phase with enhanced spin density and composite charge density wave correlations.

Shows stripe fluctuations suppress density correlations and promote pairing instabilities.

Finds that magnetic orientation affects the amplitude of composite pairing correlations.

Abstract

We study a one-dimensional electron liquid embedded in a 2D antiferromagnetic insulator, and coupled to it via a weak antiferromagnetic spin exchange interaction. We argue that this model may qualitatively capture the physics of a single charge stripe in the cuprates on length- and time scales shorter than those set by its fluctuation dynamics. Using a local mean-field approach we identify the low-energy effective theory that describes the electronic spin sector of the stripe as that of a sine-Gordon model. We determine its phases via a perturbative renormalization group analysis. For realistic values of the model parameters we obtain a phase characterized by enhanced spin density and composite charge density wave correlations, coexisting with subleading triplet and composite singlet pairing correlations. This result is shown to be independent of the spatial orientation of the stripe on the square lattice. Slow transverse fluctuations of the stripes tend to suppress the density correlations, thus promoting the pairing instabilities. The largest amplitudes for the composite instabilities appear when the stripe forms an antiphase domain wall in the antiferromagnet. For twisted spin alignments the amplitudes decrease and leave room for a new type of composite pairing correlation, breaking parity but preserving time reversal symmetry.