Light scattering study of low-energy vibrational excitations in the metallic glass Ni$_{67}$Zr$_{33}$ using electronic Raman scattering

TL;DR

This study investigates low-energy vibrational excitations in metallic glass Ni$_{67}$Zr$_{33}$ using electronic Raman scattering, revealing an unexpected increase in response upon cooling explained by electron-vibration interactions.

Contribution

It provides a theoretical explanation for the temperature-dependent Raman response in metallic glasses, highlighting the role of conduction electron scattering on localized vibrations.

Findings

Raman response increases upon cooling up to 300 cm$^{-1}$.

Electron scattering on localized vibrations explains the counterintuitive temperature dependence.

Results are applicable to disordered systems beyond the studied material.

Abstract

The Raman response of the metallic glass Ni$_{67}$Zr$_{33}$ is measured as a function of polarization and temperature and analyzed theoretically. Unexpectedly, the intensity in the range up to 300\wn increases upon cooling, which is counterintuitive when the response originates from vibrations alone as in insulators. The increase finds a natural explanation if the conduction electrons are assumed to scatter on localized vibrations with a scattering probability proportional to the Debye-Waller factor. None of our assumptions is material specific, and the results are expected to be relevant for disordered systems in general.