Influence of alloying on the electron momentum density in the Cu-Ni system

We report on the measurement of the three-dimensional electron momentum den sity (EMD) of a 22 nm Cu/22 nm Ni sandwich foil and of a Cu0.50Ni0.50 alloy film with the same thickness, which was obtained from an identical sandwic h by interdiffusion. The EMD's were measured by coincident detection of a C ompton scattered photon with its recoil electron. The experiments were perf ormed at the High-Energy beamline of the European Synchrotron Radiation Fac ility. The experimentally observed small change of the EMD due to alloying is reproduced by the Korringa-Kohn-Rostoker coherent-potential approximatio n scheme [Benedek et al., Phys. Rev. B 32, 7650 (1985)]. [S0163-1829(99)081 43-6].