Morphological instabilities of moving extended defects

Moving extended defects experience, via continuous energy exchange with the host material, a viscous-friction force which, depending on the nature of the exchange, can lead to unexpected acceleration effects. These occur at well-defined velocity thresholds where they imply phase-transition–like dynamic instabilities of the defect morphology. The apparent universal character of these phenomena is used to exemplify them by the simple scenario of a moving domain boundary which is coupled to a Ginzburg-Landau field of the bulk material.