Electronic transport in carbon nanotubes, study under magnetic field
Transport électronique dans les nanotubes de carbone; étude sous champ magnétique
Résumé
This thesis is devoted to the study of the electronic transport in carbon nanotubes. In
this scheme, we combine a high magnetic field (60T) with an electrostatic control of the
electronic doping. The goal is to show the key role played by the energy band structure
and the disorder. Several kind of metallic tubes with variable structural quality have
been studied. Depending on the ratio between the elastic mean free path (le) and the
nanotube circumference (L), different regimes appear. When le>L, a ballistic conduction is established and clearly shows the unique role of the
band structure. A complete opening of the energy gap under magnetic field is observed
(Aharonov-Bohm effect, AB). A simulation based on the Landauer formalism explains
the prominent role of the Schottky barrier at the contacts. It is the first experimental
evidence of the Aharonov-Bohm Schottky barrier modulations.
this scheme, we combine a high magnetic field (60T) with an electrostatic control of the
electronic doping. The goal is to show the key role played by the energy band structure
and the disorder. Several kind of metallic tubes with variable structural quality have
been studied. Depending on the ratio between the elastic mean free path (le) and the
nanotube circumference (L), different regimes appear. When le>L, a ballistic conduction is established and clearly shows the unique role of the
band structure. A complete opening of the energy gap under magnetic field is observed
(Aharonov-Bohm effect, AB). A simulation based on the Landauer formalism explains
the prominent role of the Schottky barrier at the contacts. It is the first experimental
evidence of the Aharonov-Bohm Schottky barrier modulations.
Cette thèse a pour objet l'étude du transport électronique dans les nanotubes de carbone grâce à l'utilisation combinée d'un fort champ magnétique (60T) et d'un contrôle électrostatique du dopage électronique. Il s'agit alors de montrer les rôles clés joués par la structure de bande en énergie et par le désordre. Plusieurs types de tubes métalliques de qualité structurale variable ont été étudiés. Selon le rapport entre le libre parcours moyen élastique (le) et la circonférence du nanotube (L), différents régimes apparaissent. Lorsque le
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