Exceptional dynamics of interacting spin liquids

TL;DR

This paper reveals that interactions in quantum spin liquids can lead to non-Hermitian phenomena like exceptional points, affecting observable properties and suggesting broader stability and new features in experimental systems.

Contribution

It demonstrates how phonons and disorder induce non-Hermitian effects in spin liquids, revealing exceptional points and rings that alter their dynamical behavior.

Findings

Exceptional points and rings appear depending on system symmetry.

Dynamical observables like neutron scattering reflect non-Hermitian effects.

Spin liquids may be more stable to perturbations than previously thought.

Abstract

We show that interactions in quantum spin liquids can result in non-Hermitian phenomenology that differs qualitatively from mean-field expectations. We demonstrate this in two prominent cases through the effects of phonons and disorder on a Kitaev honeycomb model. Using analytic and numerical calculations, we show the generic appearance of exceptional points and rings depending on the symmetry of the system. Their existence is reflected in dynamical observables including the dynamic structure function measured in neutron scattering. The results point to new phenomenological features in realizable spin liquids that must be incorporated into the analysis of experimental data and also indicate that spin liquids could be generically stable to wider classes of perturbations.