Berezinskii-Kosterlitz-Thouless Transition of Spin-1 XXZ Chains in a Staggered Magnetic Field

TL;DR

This paper numerically investigates the phase diagram of spin-1 XXZ chains in a staggered magnetic field, revealing a Berezinskii-Kosterlitz-Thouless transition and the absence of a Gaussian critical line, suggesting hidden symmetry breaking.

Contribution

It provides the first detailed numerical analysis of the BKT transition in spin-1 XXZ chains under a staggered magnetic field, highlighting differences from the spin-1/2 case.

Findings

Identifies the BKT transition between XY and antiferromagnetic phases.

Finds no Gaussian critical line separating Haldane and antiferromagnetic phases.

Suggests hidden Z2×Z2 symmetry breaking in both phases.

Abstract

Phase diagram of S=1 XXZ chain in a staggered magnetic field is obtained numerically. The Berezinskii-Kosterlitz-Thouless transition between the XY and the antiferromagnetic phases is studied by the level-spectroscopy. Moreover we find that there is no distinction between the Haldane and the antiferromagnetic phases, since the Gaussian critical line does not appear, in contrast to the $S=1/2$ case. It is expected that some hidden $Z_2\times Z_2$ symmetry breaking happens not only in the Haldane phase but also in the antiferromagnetic one.