Chiral order in spin-S XY chains

TL;DR

This paper explores chiral ordering in spin-S XY chains, revealing a gapless chiral spin nematic phase with long-range order and incommensurate correlations, using bosonization and phase diagram analysis.

Contribution

It develops a phase diagram for spin-S XY chains including a novel chiral spin nematic phase, and discusses stability and discrepancies with DMRG results.

Findings

Identification of a gapless chiral spin nematic phase

Long-range chiral order with incommensurate correlations

Conflict between stability analysis and DMRG results for integer vs. half-integer spins

Abstract

We consider the issue of chiral ordering in spin chains for an arbitrary value of the spins S. By use of bosonization according to a scheme developped by H.-J. Schulz, we obtain the phase diagram of the chain with XY exchange between nearest and next-to-nearest neighbors. We obtain a satisfactory picture including a chiral spin nematic phase which is gapless, has long-range chiral order and incommensurate spin correlations. We perform a stability analysis of this phase and point out that this analysis is in conflict with existing DMRG results that shows a difference between integer and half-integer spin case.