Evidence for unconventional electronic transport in quasicrystals

The conductivity {σ} of a series of AlCuFe and AlPdMn quasicrystals and approximant phases can be written {σ}(T)=σ₄ K+{δ}{σ}(T). The σ4K term is very low, decreases with improvement of structural quality, and varies strongly with composition. {δ}{σ}(T) is independent of the sample and increases anomalously with temperature up to 1000 K, with σ1000K/σ4K greater than 10. The results are interpreted by electronic hopping between structural entities separated by about 30 {}. Within a band picture, this process would correspond to interband transitions.