Classical signatures of quenched and thermal disorder in the dynamics of correlated spin systems

TL;DR

This paper demonstrates that semiclassical models can effectively analyze disordered correlated spin systems, revealing features like quantized excitations and continua that are indicative of complex quantum phases.

Contribution

It introduces a scalable semiclassical approach to study disordered spin systems, capturing quantum-like features in large supercell simulations.

Findings

Disordered models show quantized excitations and broad continua.

Quenched disorder causes anomalous damping.

Semiclassical methods can handle systems with ~10,000 spins.

Abstract

Neutron scattering is frequently used to look for evidence of features indicative of quantum-entangled phases of matter such as continua from fractionalisation or quantised excitations. However, the non-specificity of these features and difficulty of both fully quantum treatments and semiclassical models of disorder, make the diagnosis of such states problematic. Here, we demonstrate the feasibility of semiclassical treatments of disordered systems for supercells of $\sim 10,000$ spins. By examining a number of classically disordered models we show the presence of quantised excitations, broad continua and anomalous damping originating from quenched disorder or large classical degeneracies.