Positron Annihilation Study on the Fermi Surface of Cd–Mg Alloys

Abstract

Angular correlation measurements of annihilation photons have been made on single crystals of the Cd–Mg alloys over all compositions. It is found that the Fermi surfaces of the alloys in the Cd-rich region distort considerably from a free-electron sphere; the 3rd band “stars” and the 4th band horizontal “cigars” around the points L do not exist in Cd, and appear at 10 at% Mg accompanying an appreciable decrease of the energy gap at L . It is proposed that changes in the 4 d core states cause the sudden decrease of the energy gap.