High resolution photoemission spectroscopy study near the Fermi edge for different surfaces prepared on the icosahedral AlPdMn phase

High resolution photoemission measurements performed at low temperatures on a single-grained sample of tile AIPdMn icosahedral phase show that the den sity of states N(E) strongly depends on tile nature of tile surface. For an ordered quasicrystalline surface, prepared by Ar etching and ultra high va cuum annealing;, a dip feature is observed in N(E) near the Fermi level, wh ich energy dependence can Le analyzed with a simple square-root power law. By contrast, N(E) varies only little with energy both for a disordered surf ace and a crystalline surface of the same sample. A sharp Fermi edge is the n clearly observed. This shows that the metallic character oi the surface o f a quasicrystal is strongly reduced when the surface presents a quasicryst alline ordering.