Two-magnon correlations in Heisenberg antiferromagnets: an equation of motion study

Publisher Website
Google Scholar
Abstract
In the first of this series of four papers in which two-magnon processes and their manifestation in light and neutron scattering from Heisenberg antiferromagnets are studied, general expressions for the temperature dependent electric and magnetic dynamical susceptibilities are derived. The method employed is based on an equation of motion technique and a decoupling scheme which in essence is equivalent to a t matrix approximation in a perturbation expansion in terms of the magnon density. Kinematical effects and spin wave damping are neglected. The method is considered to be valid for the temperature regime where the usual spin wave theory is applicable, that is roughly up to 9/10TN. Applying this method to evaluate the electrical susceptibility for light absorption and scattering, the temperature dependent cross sections are obtained and for neutron scattering the longitudinal dynamical susceptibility evaluated.