Europhys. Lett.
Volume 63, Number 1, July 2003
Page(s) 63 - 68
Section Condensed matter: structure, mechanical and thermal properties
Published online 01 June 2003
DOI: 10.1209/epl/i2003-00478-8
Europhys. Lett., 63 (1) , pp. 63-68 (2003)

Semiconductivity in aluminum-transition-metal quasicrystalline alloys induced by ordering in six dimensions

M. Krajcí1, 2 and J. Hafner1

1  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

(Received 23 January 2003; accepted 2 May 2003)

We report on a class of icosahedral aluminum-transition-metal ( $\chem{Al}$-TM) alloys with true semiconducting behavior. The existence of a semiconducting gap is found to depend critically on a particular kind of $\chem{Al}$-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 $\chem{Al}$, 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 $\chem{Al}$- $\chem{Pd}$- $\chem{Re}$ turns out to be a semiconductor with a band gap filled by the localized states.

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.

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