Reversibility and hysteresis of the sharp yielding transition of a colloidal glass under oscillatory shear

TL;DR

This study investigates the reversible and hysteretic nature of a sharp transition in colloidal glasses under oscillatory shear, revealing frequency-dependent structural rearrangements and consolidating the transition's first-order characteristics.

Contribution

It combines experimental x-ray scattering and rheology with theoretical modeling to elucidate the reversibility and hysteresis of the shear-induced transition in colloidal glasses.

Findings

The transition is reversible with systematic hysteresis depending on frequency.

Hysteresis arises from frequency-dependent non-affine cage rearrangements.

The transition exhibits first-order like behavior, confirmed by measurements and models.

Abstract

The mechanical response of glasses remains challenging to understand. Recent results indicate that the oscillatory rheology of soft glasses is accompanied by a sharp non-equilibrium transition in the microscopic dynamics. Here, we use simultaneous x-ray scattering and rheology to investigate the reversibility and hysteresis of the sharp sharp symmetry change from anisotropic solid to isotropic liquid dynamics observed in the oscillatory shear of colloidal glasses [D. V. Denisov, M. T. Dang, B. Struth, A. Zaccone, and P. Schall, Sci. Rep. 5, 14359 (2015)]. We use strain sweeps with increasing and decreasing strain amplitude to show that, in analogy to equilibrium transitions, this sharp symmetry change is reversible and exhibits systematic frequency-dependent hysteresis. Using the non-affine response formalism of amorphous solids, we show that these hysteresis effects arise from frequency-dependent non-affine structural cage rearrangements at large strain. These results consolidate the first-order like nature of the oscillatory shear transition and quantify related hysteresis effects both via measurements and theoretical modelling.