On the critical dynamics of ferromagnets

The dynamic scaling functions for ferromagnets above and below the critical temperature are determined using mode coupling theory. Below the critical temperature we study isotropic ferromagnets taking into account the exchange interaction only and give the first numerical solution of the resulting mode coupling equations. In the paramagnetic phase we examine how the critical dynamics is modified by the addition of the dipoledipole interaction. On the basis of this theory we are able to explain in a unifying fashion the results of different experimental methods; i.e.: neutron scattering, hyperfine interaction and electron-spin resonance. Predictions for new experiments are made.