Title: Competing Length and Time Scales in Active Glassy Matter.

Speaker: Vincent Debets (TUE)

Abstract:

Active glassy matter, i.e., dense disordered materials composed of self-propelling particles, have rapidly emerged as an important new materials class in non-equilibrium condensed matter science and biophysics.

Controversially, however, there is still no consensus on the seemingly simple question how activity affects the glassy dynamics. In multiple recent studies, covering a wide array of materials, different conflicting results have been reported – ranging from a monotonic speedup or slowdown of the dynamics to even nonmonotonic changes upon increased activity. In the first part of the talk, we will present a unifying rationale for the seemingly conflicting views on the departure from equilibrium. Specifically, we identify the ratio of the relevant active length scale to the cage length, i.e., the length scale of local particle caging, as the key and unifying control parameter for linear active glassy matter.

In the second part of the talk, we will discuss how the inclusion of chirality (circle swimming) in active glassy matter can give rise to unexpected and new dynamical phenomena, especially compared to a standard linear active glassy fluid. Despite the added complexity, we present a full rationalization for all identified dynamical regimes of our chiral glassy fluid. Most notably, we introduce a new ‘hammering’ mechanism, unique to rapidly spinning particles in high-density conditions, that can fluidize a chiral active solid.

This event will take place in room L1.07.