Optical conductivity of the icosahedral quasicrystal Al 75.5Mn20.5Si4 and its 1/1 crystalline approximant alpha -Al72.5Mn17.4Si10.1

X. Wu, C. C. Homes, S. E. Burkov, T. Timusk, F. S. Pierce, S. J. Poon, S. L. Cooper, M. A. Karlow

Research output: Contribution to journalArticlepeer-review

Abstract

The reflectance of the metastable icosahedral quasicrystal Al 75.5Mn20.5Si4 and its 1/1 crystalline approximant alpha -Al72.5Mn17.4Si10.1 has been measured from 50 cm-1 to 46000 cm-1 at temperatures from approximately=10 K to 295 K. The optical conductivity of the icosahedral sample is similar to that reported for the stable quasicrystal Al63.5Cu 24.5Fe12; starting out from a low DC value it rises linearly with frequency up to approximately=1 eV reaching a maximum at approximately=2.2 eV with a magnitude that is comparable with transition metals, above which it decreases slowly. The conductivity of the approximant phase is similar in shape, but the overall magnitude is lower. There is a broad structure at 200 cm-1 in the quasicrystal which is resolved into at least nine sharp phonon lines in the approximant. Band structure calculations of the crystalline approximant predict a pseudogap in the electronic density of states at the Fermi surface suggesting that the unusual optical properties of the icosahedral material may also be explained by band structure arguments.

Original languageEnglish (US)
Article number026
Pages (from-to)5975-5990
Number of pages16
JournalJournal of Physics: Condensed Matter
Volume5
Issue number32
DOIs
StatePublished - 1993
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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