Orbital-Dependent Pseudogap Structure of an Al-Pd-Ru Quasicrystal Probed by X-ray Absorption and Core-Level Photoemission Spectroscopy

The unoccupied electronic states of Al-Pd-Ru quasicrystal (QC) have been investigated by X-ray absorption spectroscopy (XAS). In addition, the core-level peak binding energies have been verified by hard X-ray photoemission spectroscopy. From the comparison of the XAS spectra of the Al-Pd-Ru QC with those of single-element metals, the shift of the Al K edge can be explained by a shift in the Al 1s core level. In contrast, the shifts of the Pd and Ru L3 edges cannot be explained solely by the shifts of the core levels. These differences are due to differences in the orbital-dependent partial density of states near the Fermi level.