Electrical resistivity and magnetic susceptibility in the amorphous CrxGe1-x alloy system.

Abstract

The electrical resistivity and magnetic susceptibility of amorphous ${\mathrm{Cr}}_{\mathrm{x}}$${\mathrm{Ge}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$ alloys (0\ensuremath{\le}x\ensuremath{\le}0.65) prepared by means of the flash-evaporation method were investigated in relation to the amorphous structure. The partial pair distribution function determined by the x-ray diffraction method shows a change from the tetrahedral random network to the dense-random-packing structure with increasing Cr content. The electrical resistivity shows a transition from semiconductorlike conduction to metal-like conduction in accordance with the structure change. On the basis of the idea of Mott's hopping conduction, the density of states at the Fermi level increases with increasing Cr content and the length of decay of a localized wave function decreases with decreasing substrate temperature during evaporation. An increase in the Fermi level was deduced from analysis of the metallic conduction in terms of the Baym-Faber-Ziman theory incorporating electron mean-free-path effects. The magnetic susceptibility shows the Curie-Weiss-like behavior characterized by a significantly small localized moment per Cr atom (${\ensuremath{\mu}}_{\mathrm{eff}}$\ensuremath{\sim}0.4${\ensuremath{\mu}}_{B}$). The small moment is discussed on the basis of the idea of the virtual bound state, with local environment effects taken into account.