Evidence for the Collective Nature of the Glass Transition

TL;DR

This paper provides evidence that the glass transition in simple liquids is governed by collective equilibrium fluctuations rather than individual particle dynamics, using rheology and aging experiments.

Contribution

It demonstrates that collective fluctuations, not single-particle motions, dominate the structural relaxation in simple glass-forming liquids.

Findings

Collective equilibrium fluctuations govern structural relaxation.

Single-particle dynamics are not the primary relaxation mechanism.

Results support the collective nature of the glass transition.

Abstract

Self- and cross-correlation dynamics of deeply supercooled liquids were recently identified using photon correlation spectroscopy and spin relaxometry on the one hand, and using dielectric investigations on the other. These results fueled a controversial discussion whether the "generic" response identified by the former techniques or rather the non-universal dielectric response reflect the liquid's structural relaxation. The present study employs physical aging and oscillatory shear rheology to directly access the structural relaxation of a non-associating glass forming liquid and reveals that collective equilibrium fluctuations of simple liquids and not single-particle dynamics govern their structural relaxation.