Correlation Between Optical Conductivity and Photoemission Measurements on Pd-Y Amorphous Alloys

Abstract

Strong variations of the optical conductivity between 0.1 and 6 eV are observed for samples ranging from pure Pd to amorphous Pd30Y70. For the case of pure Pd, the optical conductivity can be divided into two regions : below 0.1 eV, Pd exhibits a Drude-like behaviour; above 0.1 eV, electronic interband transitions involving d states dominate. When the Y concentration is increased, contributions of interband transitions originating from both Y and Pd d electronic states are indentified. A confirmation of this interpretation is given by valence band photoemission spectra. Pure Pd presents a large density of d-states at the Fermi level; by increasing the Y concentration, Y electronic states are present at EF and the Pd density of states decreases rapidly. This decrease is asymmetric, i.e. the low-binding-energy side of the Pd density of states is heavily shifted towards higher energy. Both types of measurements give evidence of a strong interaction between the two constituants. © by R. Oldenbourg Verlag