Dynamic heterogeneity in hard and soft sphere colloidal glasses

作者：Rahmani Y; van der Vaart K; van Dam B; Hu Z; Chikkadi V; Schall P^*

来源：Soft Matter, 2012, 8(15): 4264-4270.

DOI：10.1039/c2sm25267h

The nature of dynamic correlations in glasses and jammed soft matter remains a puzzle. Despite the strong increase in viscosity, hard-spheres exhibit only moderate increase of dynamic correlations at the glass transition, while recent experiments on soft-spheres suggest that in these systems, correlations grow to macroscopic length. Here, we present a direct real-space analysis of dynamic correlations in hard and soft-sphere glasses. The motion of the particles is imaged directly with confocal microscopy, and the maximum dynamical susceptibility is determined systematically over a range of probe length and time scales. We elucidate the displacement vector field, and analyze correlations in the particles%26apos; direction of motion. This allows us to demonstrate the different nature of relaxations in hard and soft-sphere systems. We find that the deeply jammed soft sphere suspension shows by far longer-range dynamic correlations that are characterized by small, remarkably coherent displacements. These observations provide direct evidence of the internal elasticity that governs long-range relaxation modes in soft systems.

• 出版日期2012