Growing timescales and lengthscales characterizing vibrations of amorphous solids

TL;DR

This paper provides numerical evidence of a transition in vibrational behavior within amorphous solids, revealing growing timescales and lengthscales that may underpin universal low-temperature anomalies explained by the Gardner phase transition.

Contribution

It identifies a specific vibrational transition inside the glass phase and links it to the Gardner phase transition, offering a real-space description of the phenomenon.

Findings

Vibrational properties change at a well-defined location inside the glass phase.

Rapidly growing time and length scales accompany the transition.

Results support the Gardner phase transition as a framework for understanding glass anomalies.

Abstract

Low-temperature properties of crystalline solids can be understood using harmonic perturbations around a perfect lattice, as in Debye's theory. Low-temperature properties of amorphous solids, however, strongly depart from such descriptions, displaying enhanced transport, activated slow dynamics across energy barriers, excess vibrational modes with respect to Debye's theory (i.e., a Boson Peak), and complex irreversible responses to small mechanical deformations. These experimental observations indirectly suggest that the dynamics of amorphous solids becomes anomalous at low temperatures. Here, we present direct numerical evidence that vibrations change nature at a well-defined location deep inside the glass phase of a simple glass former. We provide a real-space description of this transition and of the rapidly growing time and length scales that accompany it. Our results provide the seed for a universal understanding of low-temperature glass anomalies within the theoretical framework of the recently discovered Gardner phase transition.