Dynamic correlations in a classical two-dimensional Heisenberg antiferromagnet.

Abstract

A Monte Carlo molecular-dynamics calculation of the dynamic structure function S(q,\ensuremath{\omega}) for the classical two-dimensional isotropic Heisenberg antiferromagnet is presented. For wave vectors near the antiferromagnetic Bragg point, S(q,\ensuremath{\omega}) is well described by a product of Lorentzians representing damped spin waves. For adequately low temperatures, the dependence of the spin-wave frequency and damping on wave vector and temperature are consistent with a dynamic scaling description of Chakravarty, Halperin, and Nelson. Even for higher temperatures a scaling description is quite well satisfied, but with a modified scaling frequency.