Random-field-driven phase transitions in the ground state of the S=1 XXZ spin chain

TL;DR

This study investigates how random magnetic fields affect the ground state phases of the S=1 XXZ spin chain, revealing phase transitions including Haldane state destruction and KT transition in the XY phase.

Contribution

It provides the first detailed analysis of the impact of random fields on the S=1 XXZ chain, contrasting with known results for the S=1/2 case.

Findings

Haldane state is destroyed at a critical random field strength.

Disappearance of string order signals the Haldane transition.

XY phase undergoes a KT transition at critical randomness.

Abstract

Ground-state of the S=1 XXZ spin chain under the influence of the random magnetic field is studied by means of the exact-diagonalization method. The S=1/2 counterpart has been investigated extensively so far. The easy-plane area, including the Haldane and the XY phases, is considered. The area suffers significantly from the magnitude of the constituent spin. Destruction of the Haldane state is observed at a critical strength of the random field, which is comparable to the magnitude of the Haldane gap. This transition is characterized by the disappearance of the string order. The XY region continues until at a critical randomness, at which a transition of the KT-universality class occurs. These features are contrasted with those of the S=1/2 counterpart.