Force-driven micro-rheology

Within a microscopic formalism for the nonequilibrium response of colloidal suspensions driven by an external force, we study the active micro-rheology of a glass-forming colloidal suspensions. In this technique, a probe particle is subject to an external force, and its nonequilibrium dynamics is monitored. Strong external forcing delocalizes the particle from its nearest-neighbor cage, resulting in a pronounced force-thinning behavior of the single-particle friction. We discuss the dynamics in the vicinity of this delocalization transition, and how long-range transport is induced for a particle that is localized in the quiescent case