Download Spécialité de M2 : Concepts Fondamentaux de la Physique

PROPOSITION DE SUJET DE THESE
ANNEE 2013
Nom du laboratoire : Laboratoire de physique des solides
Adresse : Bât.510, Université Paris-Sud, 91405 Orsay
Nom du ou des responsables de la thèse : A.Jagannathan
E-mail :[email protected]
Téléphone :0169156943
Page web :http://www.lps.u-psud.fr
Financement envisagé : bourse ministerielle
Ecole doctorale : ED107
Titre (en anglais) : Electronic properties of quasicrystals
Résumé (en anglais) : Crystalline solids can be periodic, corresponding to the vast majority of
cases, or quasiperiodic, as in the case of the hundreds of quasicrystals known to date. The
electronic properties of translationally invariant systems, where the Bloch Theorem applies,
have been extensively studied, whereas the physics of quasiperiodic systems is still in its
infancy. Quasicrystals are experimentally found to exhibit behaviors ranging from metallic,
to semiconducting or insulating, and the variety of behavior is not yet understood
theoretically.
In this project, we propose to study the quantum dynamics of wave packets as a function of
energy and initial position. Unlike periodic solids, where the wave packet grows linearly with
time, and in contrast with strongly disordered systems, where wave packets are localized,
one expects a new, possibly multifractal, behavior in quasicrystals. Although results exist for
simple 1 dimensional quasiperiodic models, not much is known for higher dimensional
quasicrystals. This project will consist of theoretical analyses as well as numerical simulations
of tight-binding models of electrons in 2 dimensional quasicrystals. The results will be useful
for interpretation of experimental studies of diffusion and transport in quasicrystals.
One of the motivations for this project is recent work showing that a new kind of
quasicrystal can be realized by trapping cold atoms in an optical potential 1. This makes it
possible to realize various tight-binding models, and to experimentally study the behavior of
atoms in the strongly interacting, or non interacting limit, in the presence of disorder, etc.
1. A.Jagannathan and M. Duneau, Europhysics Lett. (to appear 2014)
Mots clés 4 ou 5 (en anglais) : electronic properties,quasiperiodicity, tight-binding models
Profil, compétences souhaitées :Prospective candidates should possess a working
background in theoretical condensed matter (solid state) physics, quantum statistical
physics, and mathematical methods.