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Phys. Rev. B 73, 184203 (2006) [14 pages]

Use of periodic approximants in a dynamical LEED study of the quasicrystalline tenfold surface of decagonal Al-Ni-Co

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K. Pussi
Department of Electrical Engineering, Lappeenranta University of Technology, P.O. Box 20, FIN-53851 Lappeenranta, Finland

N. Ferralis
Physics Department and Materials Research Institute, Penn State University, University Park, Pennsylvania 16802, USA

M. Mihalkovic
Slovak Academy of Sciences, Dubravska Cesta 9, Bratislava 84228, Slovakia

M. Widom
Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA

S. Curtarolo
Department of Materials Science and Mechanical Engineering, Duke University, Durham, North Carolina 27708, USA

M. Gierer
Institute for Crystallography and Applied Mineralogy, Theresienstrasse 41, 80333 München, Germany

C. J. Jenks, P. Canfield, and I. R. Fisher*
Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA

R. D. Diehl
Physics Department and Materials Research Institute, Penn State University, University Park, Pennsylvania 16802, USA

Received 8 February 2006; revised 4 April 2006; published 12 May 2006

The determination of quasicrystal (QC) surface structures is a challenge to current surface structure techniques. Low-energy electron diffraction (LEED) is the primary technique for the determination of periodic surface structures, but application of dynamical LEED to quasicrystals requires the use of many approximations. In this study, two different approaches were used to apply dynamical LEED to the structure of the tenfold surface of decagonal Al73Ni10Co17. One method (method 1) involves the use of a quasicrystalline model along with approximations that average over the composition and local geometries. The other method (method 2) uses periodic models that approximate the actual local QC structure (approximants) in more exact, atomistic calculations. Although the results using the two methods were consistent, the results of the approximant analysis (method 2) suggested a different way to apply the approximations in method 1, resulting in a better fit between experimental and calculated beams. Thus, periodic approximant structure models can provide a simpler and more efficient method for the determination of local geometries in QC surfaces, and may also facilitate analyses using quasicrystal models.

© 2006 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.73.184203
DOI:
10.1103/PhysRevB.73.184203
PACS:
61.14.Hg, 61.44.Br, 68.35.Bs

*Present address: Department of Applied Physics, Stanford University, Stanford CA 94305.

 
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