Electronic Properties and Complexity of Al-Based Complex Metallic Alloys

As a consequence of their structural complexity, the electron transport properties of Al-based complex metallic alloys scale as simple power laws of the number of atoms in the primitive unit cell. Furthermore, presence in energy space of localised, d-like states below the Fermi level is systematically observed, even in the absence of any transition metal constituting element. The relative intensity of this contribution to the total density of states correlates with the structural complexity of the compound. Thus, complexity plays a key role, via Hume-Rothery, hybridization effects and most probably hopping, in the selection, formation and stability of Al-based complex metallic alloys. The results are interpreted in terms of self-organized criticality. In order to promote discussion about the essence of the quasicrystalline state ("why are the atoms where they are?"), a speculative model is suggested.