Observation of strongly heterogeneous dynamics at the depinning transition in a colloidal glass

TL;DR

This study experimentally investigates the heterogeneous and intermittent dynamics of colloidal particles near the depinning transition in a glass, revealing insights into the microscopic behavior of driven glassy systems.

Contribution

It provides experimental evidence of heterogeneous dynamics at the depinning transition in colloidal glasses, supported by mode coupling theory calculations.

Findings

Intermittent dynamics observed near the depinning threshold

Linear response relates mean displacement to mean squared displacement

Mode coupling theory explains the experimental observations

Abstract

We study experimentally the origin of heterogeneous dynamics in strongly driven glass-forming systems. Thereto, we apply a well-defined force with a laser line trap on individual colloidal polystyrene probe particles seeded in an emulsion glass composed of droplets of the same size. Fluid and glass states can be probed. We monitor the trajectories of the probe and measure displacements and their distributions. Our experiments reveal intermittent dynamics around a depinning transition at a threshold force. For smaller forces, linear response connects mean displacement and quiescent mean squared displacement. Mode coupling theory calculations rationalize the observations.