Abstract
Photoemission spectra of the valence band in an Al-Cu-Fe icosahedral phase are studied at excitation photon energies near the Fe threshold. The constant-initial-state spectra in the binding energy region between 0-2 eV show a resonant characteristic. The spectrum has an asymmetric shape, in which the weak peak is on the lower photon energy side and the strong dip is on the higher side. It's resonant energy seems to be slightly smaller than the 3p3d core excitation energy of an Fe natural form. The Fe 3d bands are located in the region ranging from EF to 2-2.5 eV below it, with the maximum contribution at around 0.7 eV binding energy. The smaller binding energy of Fe 3d bands suggests that Fe atoms have small numbers of extra electrons transferred from the other elements. The smaller binding energy (corresponding exactly to Fe 3d states sitting just below EF) is consistent with Friedel's suggestion that the stability of the icosahedral phase is enhanced by a crossing effect of the 3d states with a nearly free electron-like state below EF which enhances the energy gap of the Brillouin zone.
Published Version
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