ELECTRONIC DISTRIBUTIONS IN QUASI-CRYSTALLINE AL-PD-MN ALLOYS

We report on experimental valence and conduction electronic distributions of quasicrystalline Al-Mn-Pd alloys probed using the soft x-ray emission and absorption spectroscopy techniques. The various partial distributions are adjusted in the binding energy scale in order to investigate the electronic interactions characteristic in the material. In the valence band, interaction exists between Al states and Mn 3d states near the Fermi level and with Pd 4d states in the middle of the band. At the Fermi level the intensity of the Al 3p states is very low and a rather wide pseudo-gap is observed. In the conduction band, interaction exists also between Al p-Mn d states in the energy range of the absorption edge. Pd d-s states are found about 2 eV beyond the Fermi level. It is suggested that unlike the case of Mn, a small charge transfer may exist from Al to Pd states. Adjustment of Al 3p and Al p distributions at the same intensity at the Fermi level shows that the density of available Al p conduction states is dramatically decreased in the quasicrystal in comparison to pure Al. We propose that this could be connected to the existence of numerous narrow gaps and spikes in the densities of states as predicted theoretically elsewhere for crystal approximant phases with very large unit cells.