Double zigzag spin chain in strong magnetic field close to saturation

TL;DR

This paper investigates the phase diagram of a frustrated double zigzag spin chain near saturation, revealing complex phases including two-component Luttinger liquids and chiral states through analytical and numerical methods.

Contribution

It introduces a detailed analysis of the nearly-saturated phase diagram of a frustrated spin tube, combining effective bosonic quasiparticle interactions with DMRG simulations.

Findings

Identification of multiple phases including two-component Luttinger liquids and chiral phases.

Good agreement between analytical predictions and numerical DMRG results.

Elucidation of the role of bound magnons in the phase behavior.

Abstract

We study the ground state phase diagram of a frustrated spin tube in a strong external magnetic field. This model can be viewed as two coupled zigzag spin chains, or as a two-leg spin ladder with frustrating next-nearest-neighbor couplings along the legs, and its study is motivated by the physics of such materials as Sulfolane-Cu_{2}Cl_{4} and BiCu_{2}PO_{6}. In magnetic fields right below the saturation, the system can be effectively represented as a dilute gas of two species of bosonic quasiparticles that correspond to magnons with inequivalent incommensurate momenta at two degenerate minima of the magnon dispersion. Using the method previously proposed and tested for frustrated spin chains, we calculate effective interactions in this two-component Bose gas. On this basis, we establish the phase diagram of nearly-saturated frustrated spin tube, which is shown to include the two-component Luttinger liquid, two types of vector chiral phases, and phases whose physics is determined by the presence of bound magnons. We study the phase diagram of the model numerically by means of the density matrix renormalization group technique, and find a good agreement with our analytical predictions.