Photoemission studies of the sputter-induced phase transformation on the Al–Cu–Fe surface

The surface of a single grain icosahedral (i) Al–Cu–Fe quasicrystalline sample is studied as a function of annealing temperature using ultra-violet photoemission spectroscopy (UPS). Reflection high-energy electron diffraction and X-ray photoelectron spectroscopy are also performed to verify surface structure and composition. The sputtered surface shows structure and chemical composition consistent with that of β-Al–Cu–Fe cubic phase together with a sharp Fermi cut-off. With increasing annealing temperature, the surface structure and composition reverts to that of the quasicrystal. This transformation is correlated with a decrease of the spectral intensity at the Fermi level (EF). Analysis of the UPS spectra in the region near EF is performed by fitting the data with a pseudogap function.