Speaker: Muhittin Mungan, Bogazici University, Istanbul
Abstract: We present a toy charge density wave (CDW) model in 1d exhibiting a depinning transition with threshold force and configurations that can be worked out explicitly. Due to the periodic boundary conditions imposed, the threshold configuration has a set of topological defects whose location and number depend on the realization of the random phases. Approaching threshold, these defects are relocated by avalanches whose size dependence on the external driving force is described by a record-breaking process. We find that the depinning transition in this model is a critical phenomenon, The exact avalanche size distributions and their dependence on the external force are obtained. Remarkably, the scaling exponents associated with the critical behavior depend on (1) the initial conditions and (2) the relationship between the system size and the pinning strength. This is joint work with David C. Kaspar, UC Berkeley.