Activities
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Seminars
| Seminar on Theoretical and Computational Physics:
| | Title | Electronic structure and transport properties in graphene and rotated graphene bilayers
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| Speaker | Dr. Guy Trambly de Laissardière
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| Affiliation | Laboratoire de Physique Théorique et Modélisation (LPTM - UMR 8089) - Université de Cergy-Pontoise / CNRS
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| Date | Tuesday, 19-11-2013
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| Time | 10:00 AM
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| Location | Meeting room, first floor, Institute of physics, 10 Dao Tan, Ba Dinh, Hanoi
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| Abstract | On electronic structure in rotated graphene bilayers, we address the long lasting problem of the origin of the Moiré pattern observed on STM images (for graphene multi layers and graphite). The general belief is that the STM contrast in Moiré patterns is related to the difference in the local density of states for different stacking regions. For large and intermediated rotation angles, we present analytical and numerical studies of the electronic structure which compare well to STM spectra. For very small angles, this Moiré pattern ultimately leads to electronic confinement in AA regions at some energies close to the Dirac point.
We propose a unified description of transport in graphene with adsorbates that fully takes into account localization effects and loss of electronic coherence due to inelastic processes. We focus in particular on the role of the scattering properties of the adsorbates and analyse in detail cases with resonant or non resonant scattering. For both models we identify several regimes of conduction depending on the value of the Fermi energy. Sufficiently far from the Dirac energy and at sufficiently small concentrations the semi-classical theory can be a good approximation. Near the Dirac energy we identify different quantum regimes, where the conductivity presents universal behaviours. Transport in rotated graphene bilayers is also discussed.
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