An atomic mechanism for the boson peak in metallic glasses

TL;DR

This paper models the boson peak in metallic glasses through local shear rearrangements and elasticity theory, providing insights into vibrational modes and their coupling to sound waves.

Contribution

It introduces a novel atomic-level mechanism for the boson peak based on Eshelby's elasticity solutions in metallic glasses.

Findings

Calculated density of soft vibrational modes.

Quantified coupling to sound waves.

Analyzed energy and potential of structural rearrangements.

Abstract

The boson peak in metallic glasses is modeled in terms of local structural shear rearrangements. Using Eshelby's solution of the corresponding elasticity theory problem (J. D. Eshelby, Proc. Roy. Soc. A241, 376 (1957)), one can calculate the saddle point energy of such a structural rearrangement. The neighbourhood of the saddle point gives rise to soft resonant vibrational modes. One can calculate their density, their kinetic energy, their fourth order potential term and their coupling to longitudinal and transverse sound waves.