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Diffusion quantique et conductivité dans les systèmes apériodiques

Abstract : The purpose of this theoretical work is to study electronic transport in some aperiodic solids. In the independent electrons approximation and at zero temperature, the calculation of conductivity comes down to the problem of quantum diffusion of electrons in an aperiodic potential. We have worked out numerical methods allowing the computation of quantum diffusion in large tight-binding models (about one million orbitals) with any geometry. Then, these methods have been applied to two types of systems: quasicrystals and carbon nanotubes. Quasicrystals are intrinsically aperiodic and their transport properties could be explained by anomalous quantum diffusion laws. We have studied quasiperiodic models in 2 and 3 dimensions, and observed such anomalous laws. A peculiar dependence of these laws on the energy of the wavepacket, and on possible structural defects introduced in the model, was also observed. Multiwall carbon nanotubes can also present an intrinsinc aperiodicity, of which we have investigated possible effects on transport. In particular, we have studied magnetoconductance oscillations in presence of a magnetic field parallel to the nanotube axis. An effect of aperiodicity is observed on these oscillations.
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https://tel.archives-ouvertes.fr/tel-00002292
Contributor : François Triozon <>
Submitted on : Monday, January 20, 2003 - 12:21:32 PM
Last modification on : Wednesday, November 29, 2017 - 10:26:48 AM
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François Triozon. Diffusion quantique et conductivité dans les systèmes apériodiques. Physique [physics]. Université Joseph-Fourier - Grenoble I, 2002. Français. ⟨tel-00002292⟩

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