Spin and chiral orderings of frustrated quantum spin chains

TL;DR

This paper investigates the complex ordering phenomena in frustrated quantum spin chains, revealing unique chiral phases in S=1 XY chains characterized by spontaneous parity breaking, which are absent in S=1/2 and Heisenberg chains.

Contribution

It demonstrates the existence of gapless and gapped chiral phases in S=1 XY chains with competing interactions, a novel finding not observed in related spin models.

Findings

S=1 XY chain exhibits both gapless and gapped chiral phases.

Chiral phases characterized by spontaneous parity breaking and long-range chirality order.

Chiral phases are absent in S=1/2 XY and Heisenberg chains.

Abstract

Ordering of frustrated S=1/2 and 1 XY and Heisenberg spin chains with the competing nearest- and next-nearest-neighbor antiferromagnetic couplings is studied by exact diagonalization and density-matrix renormalization-group methods. It is found that the S=1 XY chain exhibits both gapless and gapped `chiral' phases characterized by the spontaneous breaking of parity, in which the long-range order parameter is a chirality, $\kappa_i = S_i^xS_{i+1}^y-S_i^yS_{i+1}^x$, whereas the spin correlation decays either algebraically or exponentially. Such chiral phases are not realized in the S=1/2 XY chain nor in the Heisenberg chains.