Characterization of surface morphologies at the Al–Pd–Mn fivefold surface

Fivefold surfaces of Al–Pd–Mn quasicrystal have been prepared under ultra-high vacuum (UHV) by sputtering and annealing above 700 K and characterized by electron diffraction, Auger spectroscopy and X-ray photoemission spectroscopy (LEED, AES, XPS). X-ray reflectivity at grazing incidence reveals that an in situ temperature annealing at 900 K is necessary to irreversibly produce the signature of a flat and bulk terminated surface. Air-AFM investigations of surfaces prepared below or in the vicinity of this transformation temperature show a large scale structure in the micrometer range with high steps and parallel terraces. Terrace morphology is dominated by clusters with a typical size of about 10 nm. Nanometer steps can coexist with this cluster structure. With UHV-STM, terrace roughness based on cluster assembly is found to extend down to the nanometer scale.