Showing papers by "Hans-Gerd Boyen published in 1990"

Photoemission valence-band structure of Hume-Rothery-type metallic glasses

Abstract: Photoemission spectra of the valence-band of Hume-Rothery-type Ag45Cu35Ge20 and Ag37.5Cu37.5Ge25 metallic glasses are reported. In the present measurements and in contrast to previous measurements on liquid-quenched samples of these alloys the authors avoid any sputter-cleaning procedure prior to the spectroscopy by vapour quenching the samples in the preparation chamber of the spectrometer. Whereas in the liquid-quenched samples no indications of distinct structure-induced effects in the electronic density of states near EF have been observed, in the new samples the existence of a minimum can clearly be seen and so the earlier conclusion is partly corrected by this paper. Structural influences on the density of states exist and can be detected by photoelectron spectroscopy in electronic states with large dispersion such as s and p states. In addition they show that the decrease of the density of states towards EF cannot be discussed in terms of sp-d hybridization effects as stated previously.

Influence of thermal relaxation and ion bombardment on the electronic properties of amorphous SiAu films

Abstract: Effects of thermal relaxation on amorphous SiAu films are investigated by means of photoelectron spectroscopy and measurements of the electrical resistivity and specific heat. Annealing of the films in the amorphous state increases the resistivity and reduces the electronic density of states at the Fermi energy. These relaxation effects can be reversed by irradiation with 5 keV argon ions at low temperature. The results are discussed in the framework of structural relaxation, clustering and a scaling theory given by McMillan (1981).