Defects, Sound Damping, and the Boson Peak in Amorphous Solids

Fuente: arXiv
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Main Authors: Flenner, Elijah, Szamel, Grzegorz
Format: Preprint
Published: 2025
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author Flenner, Elijah
Szamel, Grzegorz
author_facet Flenner, Elijah
Szamel, Grzegorz
contents Two nearly universal and anomalous properties of glasses, the peak in the specific heat and plateau of the thermal conductivity, occur around the same temperature. This coincidence suggests that the two phenomena are related. Both effects can be rationalized by assuming Rayleigh scaling of sound attenuation and this scaling leads one to consider scattering from defects. Identifying defects in glasses, which are inherently disordered, is a long-standing problem that was approached in several ways. We examine candidates for defects in glasses that represent areas of strong sound damping. We show that some defects are associated with quasi-localized excitations, which may be associated with modes in excess of the Debye theory. We also examine generalized Debye relations, which relate sound damping and the speed of sound to excess modes. We derive a generalized Debye relation that does not resort to an approximation used by previous authors. We find that our relation and the relation given by previous authors are almost identical at small frequencies and also reproduce the independently determined density of states. However, the different generalized Debye relations do not agree around the boson peak. While generalized Debye relations accurately predict the boson peak in two-dimensional glasses, they under estimate the boson peak in three-dimensional glasses.
format Preprint
id arxiv_https___arxiv_org_abs_2504_15878
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Defects, Sound Damping, and the Boson Peak in Amorphous Solids
Flenner, Elijah
Szamel, Grzegorz
Disordered Systems and Neural Networks
Soft Condensed Matter
Two nearly universal and anomalous properties of glasses, the peak in the specific heat and plateau of the thermal conductivity, occur around the same temperature. This coincidence suggests that the two phenomena are related. Both effects can be rationalized by assuming Rayleigh scaling of sound attenuation and this scaling leads one to consider scattering from defects. Identifying defects in glasses, which are inherently disordered, is a long-standing problem that was approached in several ways. We examine candidates for defects in glasses that represent areas of strong sound damping. We show that some defects are associated with quasi-localized excitations, which may be associated with modes in excess of the Debye theory. We also examine generalized Debye relations, which relate sound damping and the speed of sound to excess modes. We derive a generalized Debye relation that does not resort to an approximation used by previous authors. We find that our relation and the relation given by previous authors are almost identical at small frequencies and also reproduce the independently determined density of states. However, the different generalized Debye relations do not agree around the boson peak. While generalized Debye relations accurately predict the boson peak in two-dimensional glasses, they under estimate the boson peak in three-dimensional glasses.
title Defects, Sound Damping, and the Boson Peak in Amorphous Solids
topic Disordered Systems and Neural Networks
Soft Condensed Matter
url https://arxiv.org/abs/2504.15878