Critical dynamics of ferromagnets

The crossover in the dynamics from isotropic to dipolar critical
behaviour has been a matter of debate over many years. We review a
mode coupling theory for dipolar ferromagnets which gives a unified
explanation of the seemingly contradictory experimental situation.
The shape functions, the scaling functions for the damping
coefficients and the precise position of the crossover are
computed. Below Tc only the exchange interaction is taken into
account.