Experimental and theoretical electronic distributions in Al-Cu-based alloys

We report on experimental and calculated occupied and unoccupied electronic distributions of crystalline ${\mathrm{Al}}_2$Cu and various Al-Cu-Fe alloys. The experiments have been carried out by means of soft-x-ray-spectroscopy and photoelectron-spectroscopy techniques. The densities of states have been calculated using either the linear-muffin-tin-orbital atomic-sphere-approximation or the augmented-plane-wave methods. The comparison between experiment and calculations is discussed. We pay special attention to the effect of Fe in the various alloys and emphasize the role of Al atom neighbors. We propose that changes in Al site occupancy that induce changes in Al p-d hybridization near the Fermi level could be responsible for the modifications of the densities of states observed in quasicrystalline Al-Cu-Fe phases with respect to the crystalline Al-${\mathrm{Cu}}_2$Fe alloy.