Composition-dependent ultrafast luminescence in Cu-Ni alloys: Combined experimental and ab initio study

TL;DR

This study explores how composition affects ultrafast near-infrared luminescence in Cu-Ni alloys through combined experimental measurements and ab initio calculations, revealing complex electron relaxation behaviors.

Contribution

It provides new insights into electron relaxation dynamics in Cu-Ni alloys by combining experimental data with ab initio calculations of electron-phonon coupling.

Findings

Luminescence intensity peaks in Cu and decreases with Ni addition.

Decay rate decreases then increases with Ni content, showing non-monotonic behavior.

Good agreement between experimental results and theoretical calculations.

Abstract

Properties of Cu-Ni solid solutions have long been studied in physical and materials sciences. Yet, their many-body properties have not been well understood. Here, we investigate ultrafast luminescence in near infrared region for Cu$_{1-x}$Ni$_x$ alloys. The luminescence intensity was the highest in Cu and decreased dramatically by adding Ni, approaching close to the value for pure Ni at $x=0.45$. This composition dependence was well reproduced by calculations assuming two body scattering of the energetic electrons. The luminescent decay rate was not straightforward, i.e., it decreased first by adding Ni up to $x=0.17$ and then started to increase approaching twice the initial value at $x=0.45$. This behavior was in good agreement with ab initio calculations of electron-phonon (e-ph) coupling strength. This work provides a new perspective on the electron relaxation dynamics in solid solutions systems.