KINK MODEL FOR EXTENDED DEFECT MIGRATION: THEORY AND SIMULATIONS

The motion of extended defects in solids is the key to understanding many important physical phenomena. This paper addresses the relationship between defect velocity and driving force. Monte Carlo simulations of linear defects in two dimensions are performed. The force-velocity relationship is found to be non-linear, in disagreement with commonly used models. A new analytical model for the force-velocity relationship is derived that includes the effects of kinks on multiple levels, the non-simultaneity of kink formation, the disappearance of kinks and the non-linear kink force-velocity relationship. The resulting force-velocity relationship is relatively simple, but non-linear. This model is shown to yield excellent agreement with the simulation results over a wide range of driving forces and temperatures, and is readily extendable to a wide variety of defects in two and three dimensions.