Anomalous electronic transport in quasicrystals and related complex metallic alloys |
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Institution: | 1. Laboratoire de physique théorique et modélisation, Université de Cergy-Pontoise – CNRS UMR 8089, 95302 Cergy-Pontoise, France;2. Université Grenoble Alpes, Institut Neel, 38042 Grenoble, France;3. CNRS, Institut Neel, 38042 Grenoble, France |
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Abstract: | We analyse the transport properties in approximants of quasicrystals α-AlMnSi, 1/1-AlCuFe and for the complex metallic phase λ-AlMn. These phases present strong analogies in their local atomic structures and are related to existing quasicrystalline phases. Experimentally, they present unusual transport properties with low conductivities and a mix of metallic-like and insulating-like characteristics. We compute the band structure and the quantum diffusion in the perfect structure without disorder and introduce simple approximations that allow us to treat the effect of disorder. Our results demonstrate that the standard Bloch–Boltzmann theory is not applicable to these intermetallic phases. Indeed their dispersion relations are flat, indicating small band velocities, and corrections to quantum diffusion, which are not taken into account in the semi-classical Bloch–Boltzmann scheme, become dominant. We call this regime the small velocity regime. A simple relaxation time approximation to treat the effect of disorder allows us to reproduce the main experimental facts on conductivity qualitatively and even quantitatively. |
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Keywords: | Ab initio DFT calculation Quasicrystals Complex metallic alloys Electronic transport Calcul ab-initio Quasicristaux Alliages intermétalliques complexes Transport électronique |
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