Non-equilibrium dynamics of the glass transition: new perspectives from colloidal hard spheres

TL;DR

This study offers new insights into the glass transition in colloidal hard spheres, revealing that correlated cage fluctuations drive the slowdown and that amorphous caged states are self-organized critical, linking dynamics to thermodynamics.

Contribution

It introduces a novel experimental approach to analyze cage fluctuations and proposes a connection between glassy dynamics and the thermodynamic freezing transition.

Findings

Correlated cage fluctuations explain the dramatic slowdown.

Amorphous caged states exhibit self-organized criticality.

Onset of caging precedes thermodynamic freezing transition.

Abstract

A fresh approach to the data from experiments with hard sphere colloids yields seminal insights into the glass transition. The precise determination of the fraction of particles caged by their neighbours is unprecedented and provides cornerstone of our study. We show that the so-called "dramatic slowing" that accompanies super-packing is due to correlated cage fluctuations, rather than caging per se. Their statistics establish that the amorphous assemblies of caged particles are in states of self-organised criticality. The implied connection between the onset of caging and the thermodynamic 1st order freezing transition challenges the status quo, as does our contention that the dynamically critical amorphous assemblies are precursory to that transition.