First-order N\'eel-VBS transition in $S=3/2$ antiferromagnets

TL;DR

This paper investigates the nature of the phase transition between Ne9el and valence-bond solid phases in two-dimensional spin-3/2 antiferromagnets, finding evidence for a strongly first-order transition contrary to some theoretical expectations.

Contribution

The study provides the first quantum Monte Carlo analysis of the Ne9el-VBS transition in spin-3/2 systems, revealing a first-order transition in contrast to the continuous transition predicted by deconfined criticality.

Findings

Transition is strongly first-order in studied parameter regions.

Quantum Monte Carlo simulations are sign-problem free for this model.

Contradicts the expectation of a continuous transition in higher-spin systems.

Abstract

We study the transition between N\'eel and columnar valence-bond solid ordering in two-dimensional $S=3/2$ square lattice quantum antiferromagnets with SO(3) symmetry. According to the deconfined criticality scenario, this transition can be direct and continuous like the well-studied $S=1/2$ case. To study the global phase diagram, we work with four multi-spin couplings with full rotational symmetry, that are free of the sign-problem of quantum Monte Carlo. Exploring the phase diagram with quantum Monte Carlo simulations, we find that the phase transition between N\'eel and valence-bond solid is strongly first-order in the parts of the phase diagram that we have accessed.