Structural analysis of the fivefold symmetric surface of the Al70Pd21Mn9 quasicrystal by low energy electron diffraction

The atomic structure of the fivefold symmetric quasicrystal surface of Al70Pd21Mn9 was investigated by means of a dynamical low energy electron-diffraction analysis. Approximations are developed to address the high structural complexity of quasicrystals, yielding average layer-by-layer structural and compositional information. A mix of several relaxed bulklike terminations is found, consistently favoring dense AL-rich outermost atomic layers. These results can be understood in terns of principles known to govern surface structures of simpler, crystalline metals.