Influence of Lattice Defects on Optical Properties and Electronic Structure of Ni50Ga50

The change of the optical properties of the ordered intermetallic Hume-Rothery phase NiGa as a function of the concentration of lattice defects was measured by differential reflectometry. The lattice defects were produced by changing the composition and quenching from high temperatures. The electron bandstructure of Ni Ga was calculated with the augmented-plane-wave method. The comparison between measured and calculated results shows that the changes in the spectra could be explained with a rigidband model. The existence of free electrons in NiGa was confirmed.