Compton profiles for polycrystallineCuxNi1−xalloys: Theory and experiment

We present experimental and theoretical Compton profiles, J(q), for a series of ${\mathrm{Cu}}_{\mathrm{x}}$ ${\mathrm{Ni}}_{1\mathrm{-}\mathrm{x}}$ alloys. This is the first comprehensive study of Compton profiles in an alloy system. The experiments were carried out using 60-keV γ rays on five polycrystalline alloy samples with Cu concentrations x=0.40,0.50,0.55,0.60,0.65 and on pure Cu and pure Ni. Our computations of J(q) are based on the Korringa-Kohn-Rostoker coherent-potential approximation scheme for treating the average electronic spectrum of the alloy. The theory reproduces the main features of the observed Compton profiles. The experimental Compton profiles show a nearly linear dependence on concentration while the theoretically predicted Compton profiles are more nonlinear at low q. We discuss possible explanations for this discrepancy. We also discuss the relation between J(q) and the alloy Fermi surface.