Spontaneous energy-barrier formation in an entropy-driven glassy dynamics

TL;DR

This paper presents a phenomenological model for glassy dynamics that reveals spontaneous formation of energy barriers, leading to thermally activated aging behavior in systems with complex energy landscapes.

Contribution

It introduces a novel description of glassy dynamics through spontaneously emerging dynamical basins, highlighting energy barrier formation without explicit barriers in the landscape.

Findings

Relaxation paths often cross finite energy barriers despite lower-energy escape routes.

High fixed threshold energies are episodically reached, causing activated aging behavior.

The model's phenomenology is expected to be relevant for realistic glass-formers.

Abstract

The description of activated relaxation of glassy systems in the multidimensional configurational space is a long-standing open problem. We develop a phenomenological description of the out-of-equilibrium dynamics of a model with a rough potential energy landscape and we analyse it both numerically and analytically. The model provides an example of dynamics where typical relaxation channels go over finite potential energy barriers despite the presence of less-energy-demanding escaping paths in configurational space; we expect this phenomenon to be also relevant in the thermally activated regime of realistic models of glass-formers. In this case, we found that typical dynamical paths episodically reach an high fixed threshold energy unexpectedly giving rise to a simple thermally activated aging phenomenology. In order to unveil this peculiar aging behavior we introduce a novel description of the dynamics in terms of spontaneously emerging dynamical basins.