Extremal fluctuations driving the relaxation in glassy energy landscapes

TL;DR

This study demonstrates that large energy fluctuations, or record events, are crucial for relaxation in glassy systems, and constraining these fluctuations impedes relaxation, revealing their fundamental role in aging dynamics.

Contribution

We introduce a method to restrict record-high energy fluctuations in simulations, showing their essential role in glassy relaxation across diverse materials.

Findings

Prohibiting record-high fluctuations slows down relaxation.

Record events explain logarithmic energy decay.

Memory effects are linked to fluctuation dynamics.

Abstract

Cooperative events requiring anomalously large fluctuations are a defining characteristic for the onset of glassy relaxation across many materials. The importance of such intermittent events has been noted in systems as diverse as superconductors, metallic glasses, gels, colloids, and granular piles. Here, we show that prohibiting the attainment of new record-high energy fluctuations -- by explicitly imposing a ``lid'' on the fluctuation spectrum -- impedes further relaxation in the glassy phase. This lid allows us to directly measure the impact of record events on the evolving system in extensive simulations of aging in such vastly distinct glass formers as spin glasses and tapped granular piles. Interpreting our results in terms of a dynamics of records succeeds in explaining the ubiquity of both, the logarithmic decay of the energy and the memory effects encoded in the scaling of two-time correlation functions of aging systems.