Randomness-driven quantum phase transition in bond-alternating Haldane chain

TL;DR

This paper investigates how bond randomness affects the topological order in a spin-1 bond-alternating Heisenberg chain, revealing a quantum phase transition driven by randomness that destroys the Haldane phase's topological order.

Contribution

It provides the first detailed analysis of the stability of topological order under bond randomness using quantum Monte Carlo simulations.

Findings

Weak randomness does not destroy the dimer and Haldane phases.

Strong randomness destroys the topological order in the Haldane phase.

A quantum phase transition occurs at a critical randomness strength.

Abstract

The effect of bond randomness on the spin-gapped ground state of the spin-1 bond-alternating antiferromagnetic Heisenberg chain is discussed. By using the loop cluster quantum Monte Carlo method, we investigate the stability of topological order in terms of the recently proposed twist order parameter [M. Nakamura and S. Todo: Phys. Rev. Lett. 89 (2002) 077204]. It is observed that the dimer phases as well as the Haldane phase of the spin-1 Heisenberg chain are robust against a weak randomness, though the valence-bond-solid-like topological order in the latter phase is destroyed by introducing a disorder stronger than the critical value.