Chirally Stabilized Critical State in Marginally Coupled Spin and Doped Systems

TL;DR

This paper investigates a class of one-dimensional frustrated spin models and doped systems, revealing a chirally stabilized critical phase with unique universal properties, and analyzes their spectral and correlation characteristics.

Contribution

It provides an exact solution at a Toulouse point for a frustrated spin ladder model, uncovering its critical phase and universal properties, including spectral and correlation functions.

Findings

Identification of a chirally stabilized critical phase with non-integer central charge.

Exact solution at a Toulouse point capturing universal properties.

Analysis of spectral properties and spin correlations.

Abstract

We study a class of one-dimensional models consisting of a frustrated (N+1)-leg spin ladder, its asymmetric doped version as a special example of a Luttinger liquid in an active environment, and the N-channel Kondo-Heisenberg model away from half-filling. It is shown that these models exhibit a critical phase with generally a non-integer central charge and belong to the class of chirally stabilized spin liquids recently introduced by Andrei, Douglas, and Jerez [Phys. Rev. B 58, 7619 (1998)]. By allowing anisotropic interactions in spin space, an exact solution in the N=2 case is found at a Toulouse point which captures all universal properties of the models. At the 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. The Toulouse limit solution enables us to discuss the spectral properties, the computation of the spin-spin correlation functions as well as the estimation of the NMR relaxation rate of the frustrated three-leg ladder. Finally, it is shown that the critical point becomes unstable upon switching on some weak backscattering perturbations in the frustrated three-leg ladder.