Phase diagram of the random Heisenberg antiferromagnetic spin-1 chain

TL;DR

This paper introduces a new real space RG method to analyze the phase diagram of the disordered Heisenberg spin-1 chain, revealing a transition from a random singlet phase to a Griffiths and Haldane phase as disorder varies.

Contribution

A novel perturbative real space RG approach that effectively studies weak disorder in spin-1 chains, overcoming limitations of previous methods.

Findings

Identification of a random singlet phase at strong disorder

Crossover from Griffiths to Haldane phase with decreasing disorder

Zero temperature phase diagram mapped as a function of disorder

Abstract

We present a new perturbative real space renormalization group (RG) to study random quantum spin chains and other one-dimensional disordered quantum systems. The method overcomes problems of the original approach which fails for quantum random chains with spins larger than S=1/2. Since it works even for weak disorder we are able to obtain the zero temperature phase diagram of the random antiferromagnetic Heisenberg spin-1 chain as a function of disorder. We find a random singlet phase for strong disorder and as disorder decreases, the system shows a crossover from a Griffiths to a disordered Haldane phase.