BAND-STRUCTURE GAP AND ELECTRON-TRANSPORT IN METALLIC QUASI-CRYSTALS AND CRYSTALS

Studies of icosahedral quasicrystals have revealed a conductivity pseudogap much narrower than the density-of-states pseudogap, resulting in a rapid suppression of electron diffusivity inside the latter. In contrast, measurements of the new metallic compound Al2Ru show the formation of a semiconducting-like gap with localized gap states. The imminence of Anderson localization and absence of a real gap in quasicrystals are compared with current calculations of electronic properties on metallic quasiperiodic, as well as periodic, systems.