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 Al{sub 70}Pd{sub 21}Mn{sub 9}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 terms of principles known to govern surface structures of simpler, crystalline metals. {copyright} {ital 1997} {ital The American Physical Society}