Dynamics of coupled quantum spin chains

TL;DR

This paper investigates the static and dynamic behaviors of weakly coupled antiferromagnetic spin chains using a mean-field approach, predicting a narrow longitudinal mode and aligning with experimental data on CuF_3.

Contribution

It introduces a mean-field method for coupled spin chains and predicts a longitudinal mode, improving understanding beyond traditional spin wave theory.

Findings

Results agree with experiments on CuF_3.

Predicts a narrow longitudinal mode.

Aligns with scaling arguments rather than spin wave theory.

Abstract

Static and dynamical properties of weakly coupled antiferromagnetic spin chains are treated using a mean--field approximation for the interchain coupling and exact results for the resulting effective one--dimensional problem. Results for staggered magnetization, N\'eel temperature and spin wave excitations are in agreement with experiments on $\rm KCuF_3$. The existence of a narrow longitudinal mode is predicted. The results are in agreement with general scaling arguments, contrary to spin wave theory.