Field dependence of the soliton contribution to the dynamic correlation function of a classical Heisenberg antiferromagnet

Abstract

Recent theoretical and experimental work confirm the existence of solitons in the nearly classical two-dimensional (2D) Heisenberg antiferromagnet. Previous ac susceptibility measurements on (n-propyl ammonium)2MnCl4 or (PAMC), a 2D spin 5/2 antiferromagnet AFM shows that the susceptibility is strongly dependent on a weak magnetic field (≈0.2 Oe) at temperatures below TC. These data provided the motivation for a calculation of the field dependence of the static soliton structure factor. This is done by assuming the small field dependent term as a perturbation around the static soliton solution. The dynamic part of the correlation function is assumed to result from soliton–magnon scattering in the Born approximation. These field-dependent and dynamic results are combined to obtain the dynamic field-dependent correlation function.