Revealing the Link between Structural Relaxation and Dynamic Heterogeneity in Glass-Forming Liquids

TL;DR

This paper uncovers a fundamental link between structural relaxation and dynamic heterogeneity in glass-forming liquids, revealing a common time scale related to fragility that unifies their behavior near the glass transition.

Contribution

It introduces a characteristic time scale that connects dynamic heterogeneity with structural relaxation, providing a unified understanding across different glass-forming liquids.

Findings

Identifies a time scale linked to fragility.

Achieves scaling collapse of relaxation time and heterogeneity.

Reveals a characteristic temperature associated with heterogeneity.

Abstract

Despite the use of glasses for thousands of years, the nature of the glass transition is still mysterious. On approaching the glass transition, the growth of dynamic heterogeneity has long been thought to play a key role in explaining the abrupt slowdown of structural relaxation. However, it still remains elusive whether there is an underlying link between structural relaxation and dynamic heterogeneity. Here we unravel the link by introducing a characteristic time scale hiding behind an identical dynamic heterogeneity for various model glass-forming liquids. We find that the time scale corresponds to the kinetic fragility of liquids. Moreover, it leads to scaling collapse of both the structural relaxation time and dynamic heterogeneity for all liquids studied, together with a characteristic temperature associated with the same dynamic heterogeneity. Our findings imply that studying the glass transition from the viewpoint of dynamic heterogeneity is more informative than expected.