Spin-3/2 random quantum antiferromagnetic chains

TL;DR

This paper investigates the effects of disorder on spin-3/2 quantum antiferromagnetic chains using a modified renormalization group method, revealing a Griffiths phase and potential random singlet phase under extreme disorder.

Contribution

It introduces a modified perturbative renormalization group approach to analyze disordered spin-3/2 chains, identifying phases and critical behavior not previously characterized.

Findings

Existence of a quantum Griffiths phase with a disorder-dependent dynamical exponent

Potential realization of a random singlet phase under extreme disorder

Differences highlighted between this approach and other methods

Abstract

We use a modified perturbative renormalization group approach to study the random quantum antiferromagnetic spin-3/2 chain. We find that in the case of rectangular distributions there is a quantum Griffiths phase and we obtain the dynamical critical exponent $Z$ as a function of disorder. Only in the case of extreme disorder, characterized by a power law distribution of exchange couplings, we find evidence that a random singlet phase could be reached. We discuss the differences between our results and those obtained by other approaches.