Biological & Soft Matter Seminar: Yield in Soft Amorphous Materials: The Ant in the Energy Landscape Labyrinth

Abstract:

It was recently shown that yield in soft, condensed, amorphous materials and complex fluids, such as condensed colloids and emulsions, exhibits a dynamical non-equilibrium phase transition from asymptotically periodic to asymptotically chaotic, diffusive dynamics when subject to oscillatory shear. However, the nature of this transition is still undecided. Here we show that the diffusive behavior of the vector of coordinates of the particles comprising the material, when subject to oscillatory shear, is analogous to that of a particle diffusing in a percolating lattice, the so-called ``ant in the labyrinth'' problem, and that yield corresponds to a percolation transition. We explain this as a transition in the connectivity of the energy landscape, which affects the phase-space regions accessible to the coordinate vector, for a given maximal strain amplitude. This transition provides a natural explanation to the limit-cycles, period doubling and diverging time-scales observed at yield.

Seminar Organizer: Guy Yaacoby