Dynamics of Thermal Effects in the Spin-Wave Theory of Quantum Antiferromagnets

TL;DR

This paper develops a master equation within spin-wave theory to analyze non-equilibrium thermal effects in quantum antiferromagnets, revealing magnon decay rates and the robustness of magnetic order at moderate temperatures.

Contribution

It introduces a closed-form analytic approach to magnon decay rates and connects them to experimentally measurable form factors in quantum antiferromagnets.

Findings

Magnon decay rates are analytically derived and related to form factors.

Magnetic order remains stable at moderate temperatures despite isotropic coupling.

The study provides insights into non-equilibrium dynamics of quantum antiferromagnets.

Abstract

We derive a master equation that allows us to study non-equilibrium dynamics of a quantum antiferromagnet. By resorting to spin-wave theory, we obtain a closed analytic form for the magnon decay rates. These turn out to be closely related to form factors, which are experimentally accessible by means of neutron and Raman scattering. Furthermore, we compute the time evolution of the staggered magnetization showing that, for moderate temperatures, the magnetic order is not spoiled even if the coupling is fully isotropic.