Composition dependence of optical gaps in copper-based Hume-Rothery alloys

Abstract

We discuss the composition dependence of a number of critical energy gaps in the Cu-based Hume-Rothery alloys $\mathrm{Cu}\mathrm{Zn}$, $\mathrm{Cu}\mathrm{Al}$, and $\mathrm{Cu}\mathrm{Ge}$. Our computations, employing the Korringa-Kohn-Rostoker coherent-potential approach, provide a remarkably simple and consistent explanation of a variety of available optical experiments on these systems. Polyvalent impurities are found to influence the spectrum of Cu in a manner which varies strongly from one solute to another.