A point detector positron annihilation study of Cu85Zn15

Abstract

A high resolution point detector geometry has been applied to the study of the angular correlation spectra from positron annihilation in Cu85Zn15 single crystals. Strong anisotropies are observed and some features are interpreted in terms of the alloy Fermi surface. A value for the [111] neck diameter is obtained which is 50% greater than that for pure copper. Considerable smearing of the expected slope discontinuity in the neighbourhood of the Fermi momentum is interpreted as evidence for Stern's theory of charging. A large anisotropy in the higher momentum contribution to the annihilation is also observed.