DYNAMICS OF DOMAINS IN DILUTED ANTIFERROMAGNETS

We investigate the dynamics of two-dimensional site-diluted Ising anti ferromagnets. In an external magnetic held these highly disordered mag netic systems have a domain structure which consists of fractal domain s with sizes on a broad range of length seals. We focus on the dynamic s of these systems during the relaxation from a long-range ordered ini tial stale to the disordered fractal-domain state after applying an ex ternal magnetic field. The equilibrium state with applied field consis ts of fractal domains with a size distribution which follows a power l aw with an exponential cutoff. The dynamics of the system can be under stood as a growth process of this fractal-domain state in such a way t hat the equilibrium distribution of domains develops during time. Foll owing these ideas quantitatively we derive a simple description of the time dependence of the order parameter. The agreement with simulation s is excellent.