Long-range strain correlations in sheared colloidal glasses

TL;DR

This study provides experimental evidence of long-range strain correlations in sheared colloidal glasses, revealing their role in flow transition and elastic behavior, which were previously unobserved in quiescent glasses.

Contribution

The paper demonstrates the existence of long-range strain correlations in sheared colloidal glasses and explores their influence on flow transition, advancing understanding of glass deformation.

Findings

Long-range correlations observed during shear deformation.

Transition from homogeneous to inhomogeneous flow at critical shear rate.

Scaling and symmetry of strain correlations characterized.

Abstract

Glasses behave as solids on experimental time scales due to their slow relaxation. Growing dynamic length scales due to cooperative motion of particles are believed to be central to this slow response. For quiescent glasses, however, the size of the cooperatively rearranging regions has never been observed to exceed a few particle diameters, and the observation of long-range correlations that are signatures of an elastic solid has remained elusive. Here, we provide direct experimental evidence of long-range correlations during the deformation of a dense colloidal glass. By imposing an external stress, we force structural rearrangements that make the glass flow, and we identify long-range correlations in the fluctuations of microscopic strain, and elucidate their scaling and spatial symmetry. The applied shear induces a transition from homogeneous to inhomogeneous flow at a critical shear rate, and we investigate the role of strain correlations in this transition.