Dynamics of topological defects in critical binary fluids, metamagnets and 3He-4He mixtures

The dynamical theory of topological defects in critical and tricritical systems is presented. Starting with the bulk stochastic equation like the time dependent Ginzburg-Landau model we derive the equation of motion of the topological defects such as interfaces and vortices in a unified way. We are primarily concerned with critical binary fluids, metamagnets and 3He-4He mixtures. The method utilized here is based on the idea originally used by Thiele in his theory of magnetic bubbles. (orig.)