Slow relaxation and aging phenomena at nano-scale in granular materials

TL;DR

This paper investigates how thermal fluctuations influence slow relaxation and aging in granular materials, revealing their significant impact on macroscopic acoustic effects and proposing a universal mechanism for systems with metastable states.

Contribution

It introduces the role of thermal fluctuations in granular relaxation and aging, and proposes a general mechanism for systems with metastable states.

Findings

Thermal fluctuations affect mesoscopic asperities in granular matter.

Acoustic effects can observe thermal influence on macroscopic scale.

A universal mechanism explains slow relaxations and aging in metastable systems.

Abstract

Complex systems having metastable elements often demonstrate nearly log-time relaxations and a kind of aging: repeated stimuli weaken the system's relaxational response. Granular matter is known to exhibit a wealth of such behaviors, for which the role of thermal fluctuations is usually ignored. However, we demonstrate that the latter can pronouncedly affect contacting mesoscopic-scale asperities and be macroscopically observed via appropriate acoustic effects. We also propose a mechanism comprising slow relaxations and aging as intrinsic properties of a wide class of systems with metastable states.