Surface Fluctuations of an Aging Colloidal Suspension: Evidence for Intermittent Quakes

TL;DR

This study investigates the surface fluctuations of aging colloidal suspensions, revealing that their dynamics become intermittent over time with uncorrelated quake events that influence surface behavior temporarily.

Contribution

It provides direct measurements of surface fluctuations in aging colloids, demonstrating the occurrence of intermittent quakes and their statistical properties.

Findings

Surface fluctuations become intermittent with age.

Large slope changes are associated with quake events.

Quakes are uncorrelated but influence surface temporarily.

Abstract

We present measurements of the thermal fluctuations of the free surface of an aging colloidal suspension, Laponite. The technique consists in measuring the fluctuations of the position of a laser beam that reflects from the free surface. Analysing the data statistics, we show that, as the fluid ages, the dynamics becomes intermittent. The intermittent events correspond to large changes in the local slope of the free surface over a few milliseconds. We show that those quakes are uncorrelated, although they are kept in memory by the surface over short time scales.