Volume 63, Number 1, July 2003
|63 - 68
|Condensed matter: structure, mechanical and thermal properties
|01 June 2003
Semiconductivity in aluminum–transition-metal quasicrystalline alloys induced by ordering in six dimensions
Institut für Materialphysik and Center for Computational Materials Science Universität Wien - Sensengasse 8/12, A-1090 Wien, Austria
2 Institute of Physics, Slovak Academy of Sciences Dúbravská cesta 9, SK-84228 Bratislava, Slovak Republic
Accepted: 2 May 2003
We report on a class of icosahedral aluminum–transition-metal (-TM) alloys with true semiconducting behavior. The existence of a semiconducting gap is found to depend critically on a particular kind of -TM ordering defined by a simple rule in the 6-dimensional superspace. Any deviation from this 6D order leads to the formation of strongly localized defect states in the gap. We show that by a judicious selection of transition metals to be alloyed with , we can find alloys with a semiconducting gap at the Fermi level for a hierarchy of approximants to a quasicrystal. As the electron/atom ratio placing the Fermi level into the gap is slightly different for each approximant, this suggests that the gap persists also in the quasiperiodic limit. Icosahedral -- turns out to be a semiconductor with a band gap filled by the localized states.
PACS: 61.44.Br – Structure of solids and liquids; crystallography: Quasicrystals / 71.20.-b – Electron density of states and band structure of crystalline solids / 71.23.Ft – Electronic structure of bulk materials: Quasicrystals
© EDP Sciences, 2003
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