arXiv:cond-mat/9604144 · Physical Review Letters
Dynamics of Coupled Quantum Spin Chains
Heinz J. Schulz
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 ${\mathrm{KCuF}}_{3}$. The existence of a narrow longitudinal mode is predicted. The results are in agreement with general scaling arguments, contrary to spin wave theory.