Direct Identification of the Glass Transition: Growing Length Scale and the Onset of Plasticity

TL;DR

This paper provides direct evidence of a diverging length scale at the glass transition, links it to the disappearance of fluid-like regions, and connects fluid-like regions under strain to the onset of plasticity in glasses.

Contribution

It offers the first direct measurement of a diverging length scale at the glass transition and relates fluid-like regions to plasticity onset under strain.

Findings

Diverging length scale at the glass transition

Disappearance of fluid-like regions at the transition

Fluid-like regions under strain signal plasticity onset

Abstract

Understanding the mechanical properties of glasses remains elusive since the glass transition itself is not fully understood, even in well studied examples of glass formers in two dimensions. In this context we demonstrate here: (i) a direct evidence for a diverging length scale at the glass transition (ii) an identification of the glass transition with the disappearance of fluid-like regions and (iii) the appearance in the glass state of fluid-like regions when mechanical strain is applied. These fluid-like regions are associated with the onset of plasticity in the amorphous solid. The relaxation times which diverge upon the approach to the glass transition are related quantitatively.