Electronic transport properties of amorphous and quasicrystals TMxAl100−x alloys

The electrical resistivity ρ(T), and the thermopower S(T), of amorphous films of (Mn,Fe)xAl100−x (15 ⩽ x ⩽ 50), as well Al70.5 Pd21Mn8.5 and Al62.5Cu25Fe12.5 have been measured in the temperature range between 5 K and 350 K. The amorphous films were prepared in situ by the sequential flash-evaporation technique at low temperature (T ≈ 10 K) and the quasicrystalline phases were obtained after annealing the samples to 900 K. The resistivity as well as the thermopower both show dependences on the TM-content and a pronounced non- metallic behaviour versus temperature. This behaviour can be explained in the frame of electronic stabilized amorphous systems, very similar to a Peierls effect in 1D-systems or Hume–Rothery alloys, where hybridisation effects of Al-p with TM-d electrons play an important rule. The electronic stabilization explanation is supported by resistivity and thermopower measurements, together with measurements of the static structure factor and the crystallisation behaviour of the amorphous samples. Finally, the resistivity and the thermopower both are fit to a model based on LMTO calculations, developed for TM-Al quasicrystalline materials, and supplies our description of the electronic density of states around the Fermi energy.