Effect of microstructures on the electron-phonon interaction in the disordered metals Pd$_{60}$Ag$_{40}$

TL;DR

This study investigates how microstructural differences in disordered Pd$_{60}$Ag$_{40}$ films affect electron-phonon interactions, revealing an unexpected temperature and disorder dependence and highlighting the influence of deposition methods.

Contribution

It demonstrates an anomalous $1/\tau_{ep} \propto T^2\ell$ dependence and shows that electron-phonon coupling varies with microstructural quality and deposition technique.

Findings

Anomalous $T^2\ell$ dependence of electron-phonon scattering time.

Stronger electron-phonon coupling in DC-sputtered films.

Sensitivity of electron-phonon interaction to microstructural quality.

Abstract

Using the weak-localization method, we have measured the electron-phonon scattering times $\tau_{ep}$ in Pd$_{60}$Ag$_{40}$ thick films prepared by DC- and RF-sputtering deposition techniques. In both series of samples, we find an anomalous $1/\tau_{ep} \propto T^2\ell$ temperature and disorder dependence, where $\ell$ is the electron elastic mean free path. This anomalous behavior cannot be explained in terms of the current concepts for the electron-phonon interaction in impure conductors. Our result also reveals that the strength of the electron-phonon coupling is much stronger in the DC than RF sputtered films, suggesting that the electron-phonon interaction not only is sensitive to the total level of disorder but also is sensitive to the microscopic quality of the disorder.