(29d) Random Organization: Irreversibility & Collisions, a Dynamic Phase Transition

Understanding self-organization is one of the key tasks for controlling and manipulating the structure of materials at the micro- and nanoscale. In general, self-organization is driven by interparticle potentials and is opposed by the chaotic dynamics characteristic of many driven non-equilibrium systems. Here we introduce a new model that shows how the irreversible collisions that generally produce diffusive chaotic dynamics can also cause a system to self-organize to avoid future collisions. This can lead to a self-organized non-fluctuating quiescent state, with a dynamical phase transition separating it from fluctuating diffusing states. We apply the model to recent experiments on periodically sheared particle suspensions where a transition from reversible to irreversible behavior was observed. New experiments presented here exhibit remarkable agreement with this simple model. More generally, the model and experiments provide new insights into how driven systems can self-organize.