A unified picture of phonon anomalies in crystals and glasses

TL;DR

This paper reviews a resonant-damping model that unifies the understanding of phonon anomalies like van Hove singularities in crystals and boson peaks in glasses, linking vibrational features across different solid states.

Contribution

It introduces a resonant-damping framework that explains both van Hove and boson peaks within a single theory, extending previous models and connecting to microscopic mechanisms.

Findings

The model explains coexistence of van Hove and boson peaks in materials.

It links phonon damping to vibrational softening across solids.

Provides a unified theoretical approach to vibrational anomalies.

Abstract

Phonon spectra in solids often display anomalies that defy the simple Debye law, most prominently the van Hove singularity in crystals and the boson peak in glasses. Although traditionally regarded as distinct, both features are increasingly recognized as sharing a common physical origin. In a recent work, G. Ding et al. (Nat. Phys. 2025) propose a resonant-damping model that unifies these anomalies within a single framework. By coupling phonon damping to vibrational softening, their theory explains why some materials exhibit van Hove peaks, others boson peaks, and many show both. This advance extends earlier ideas and theories of Baggioli and Zaccone on the competition between phonon propagation and damping, while also connecting to microscopic mechanisms such as nonaffine motions in glasses. The resonant-damping paradigm thus offers a promising step toward a unified understanding of vibrational anomalies across ordered and disordered solids.