New Chiral Universality Class in a Frustrated Three-Leg Spin Ladder

TL;DR

This paper introduces a new chiral universality class in a frustrated three-leg spin ladder, revealing a critical phase with unique properties and an exact solution at a special point, expanding understanding of quantum criticality in spin systems.

Contribution

It identifies a novel chiral critical phase in a frustrated spin ladder and provides an exact solution capturing its universal properties, including spectral and correlation features.

Findings

Discovery of a critical phase with central charge C=2

Exact solution at a Toulouse point for anisotropic interactions

Spectral properties and correlation functions characterized

Abstract

We study a model of three $S=1/2$ antiferromagnetic Heisenberg spin chains weakly coupled by on-rung and plaquette-diagonal interchain interactions. It is shown that the model exhibits a critical phase with central charge C=2 and belongs to the class of ``chirally stabilized'' liquids recently introduced by Andrei, Douglas, and Jerez. By allowing anisotropic interactions in spin space, we find an exact solution at a Toulouse point which captures all universal properties of the model, including the SU(2) symmetric case. At the new critical point the massless degrees of freedom are described in terms of an effective $S = 1/2$ Heisenberg spin chain and two critical Ising models. We discuss the spectral properties of the model, compute spin-spin correlation functions and estimate the NMR relaxation rate.