Theory of sound attenuation in glasses: The role of thermal vibrations

TL;DR

This paper demonstrates that thermal vibrations significantly contribute to sound attenuation in glasses, challenging previous assumptions and showing effects comparable to crystalline materials at ultrasonic and hypersonic frequencies.

Contribution

It introduces a realistic model of amorphous silicon showing thermal vibrations cause substantial sound attenuation, driven by large Grüneisen parameters of low-frequency modes.

Findings

Thermal vibrations induce notable sound attenuation in glasses.

Attenuation levels are comparable or larger than in crystals.

Large Grüneisen parameters explain the high attenuation.

Abstract

Sound attenuation and internal friction coefficients are calculated for a realistic model of amorphous silicon. It is found that, contrary to previous views, thermal vibrations can induce sound attenuation at ultrasonic and hypersonic frequencies that is of the same order or even larger than in crystals. The reason is the internal-strain induced anomalously large Gr\"uneisen parameters of the low-frequency resonant modes.