Nonequilibrium pattern formation in strongly interacting driven colloids

Abstract

Dynamical instabilities are discussed for strongly interacting colloidal suspensions which are driven into nonequilibrium by an external field in the limit where hydrodynamic interactions can be neglected. Brownian dynamics computer simulations indicate that stripe-like patterns of particles driven alike are spontaneously formed if the external drive exceeds a critical strength. Recent previous studies of stripe formation obtained for symmetric equimolar mixtures in the steady state are reviewed. These results are then extended in two directions: first, we show that stripe-like segregation occurs also in asymmetric mixtures and observe an additional compression/expansion effect in the stripes composed of the small/large particles. Second, we study the relaxation into the stripe-patterned steady state starting from a uniform demixed state and show that different transient processes such as jamming, anisotropic coarsening and void formation are relevant on the route into the stratified steady state.