A consequence of local equilibration and heterogeneity in glassy materials

TL;DR

This paper explores how local equilibration and heterogeneity influence the fluctuation-dissipation theorem in glassy materials, extending previous theories to finite timescales supported by numerical simulations.

Contribution

It introduces a scaling-based extension of the fluctuation-dissipation theorem applicable to non-asymptotic regimes in glassy systems.

Findings

Supports the generalized FDT through extensive simulations

Applicable across different dimensions and dynamics

Highlights the role of local equilibration in glassy behavior

Abstract

The existence of a generalized fluctuation-dissipation theorem observed in simulations and experiments performed in various glassy materials is related to the concepts of local equilibration and heterogeneity in space. Assuming the existence of a dynamic coherence length scale up to which the system is locally equilibrated, we extend previous generalizations of the FDT relating static to dynamic quantities to the physically relevant domain where asymptotic limits of large times and sizes are not reached. The formulation relies on a simple scaling argument and has thus not the character of a theorem. Extensive numerical simulations support this proposition. Our results quite generally apply to systems with slow dynamics, independently of the space dimensionality, the chosen dynamics, or the presence of disorder.