A continuum model reproducing the multiple frequency crossovers in acoustic attenuation in glasses

TL;DR

This paper introduces a continuum viscoelastic model that accurately captures the complex frequency-dependent acoustic attenuation in glasses, spanning GHz to THz, including temperature effects, with a novel multi-scale approach.

Contribution

The work presents a new continuum model that reproduces multiple frequency crossovers in acoustic attenuation in glasses, incorporating temperature dependence through a hierarchical multi-scale strategy.

Findings

Successfully reproduces $oldsymbol{ ext{omega}^2- ext{omega}^4- ext{omega}^2}$ attenuation dependence

Models attenuation over three orders of magnitude from GHz to THz

Includes temperature effects in the attenuation behavior

Abstract

Structured metamaterials are at the core of extensive research, promising for acoustic and thermal engineering. Nevertheless, the computational cost required for correctly simulating large systems imposes to use a continuous model to describe the effective behavior without knowing the atomistic details. Crucially, a correct description needs to describe both the extrinsic interface-induced and the intrinsic atomic scale-originated phonon scattering, especially when the component material is made of glass, a highly dissipative material in which wave attenuation is strongly dependent on frequency as well as on temperature. In amorphous systems, the effective acoustic attenuation triggered by multiple mechanisms is now well characterized and exhibits a nontrivial frequency dependence with a double crossover of power laws. In this work, we propose a continuum viscoelastic model based on the hierarchical strategy multi-scale approach, able to reproduce well the phonon attenuation in a large frequency range, spanning three orders of magnitude from GHz to THz with a $\omega^2-\omega^4-\omega^2$ dependence, including the influence of temperature.