Generalized Fluctuation-Dissipation Relation and Effective Temperature upon Heating a Deeply Supercooled Liquid

TL;DR

This study demonstrates a generalized fluctuation-dissipation relation in supercooled liquids upon heating, revealing an effective temperature lower than the bath temperature and its relation to phase space exploration.

Contribution

It introduces a generalized fluctuation-dissipation relation applicable during heating of supercooled liquids, highlighting the concept of an effective temperature with specific properties.

Findings

Effective temperature is lower than bath temperature during heating.

The relation exhibits a two-step shape similar to cooling but with opposite violation.

Effective temperature depends on time and relates to phase space in aging.

Abstract

We show that a generalized fluctuation-dissipation relation applies upon instantaneously increasing the temperature of a deeply supercooled liquid. This has the same two-step shape of the relation found upon cooling the liquid, but with opposite violation, indicating an effective temperature that is lower than bath temperature. We show that the effective temperature exhibits some sensible time-dependence and that it retains its connection with the partitioned phase space visited in ageing. We underline the potential relevance of our numerical results for experimental studies of the fluctuation-dissipation relation in glassy systems.