Avalanches and self-organization in the dynamics of cellular magnetic domain patterns (invited)

Cellular magnetic domain patterns in magnetic garnet films are an example of a spatially-extended metastable system whose evolution is limited by topological constraints. For sufficiently large applied magnetic fields, the entire pattern is under tension and can respond to local perturbations via large collective motions. In this regime disordered cellular patterns respond to small increases in applied field or to manual cell breakage via avalanches of sequential cell destruction which sweep through the pattern via the motion of cell walls. After one avalanche has stopped another can be started by a small increase in field or by another manual cell breakage; the system thus tends to self-organize into barely stable states. The measured distributions of avalanche size and duration are best fit by power laws. These features suggest that cellular avalanches may be an example of self-organized criticality.