Guy Trambly de Laissardière

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My research activity has mainly deal with the electronic confinement of Dirac electrons in twisted bilayer graphene, and the quantum transport in graphene sheet with adsorbates and in perfect quasiperiodic tilings.

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 large and intermediated rotation angles, we present analytical and numerical studies of the electronic structure which compare well to STM spectra [1,3]. For very small angles, Moiré pattern ultimately leads to electronic confinement in AA regions at some energies close to the Dirac point [1,2].

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 [4]. 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 [3,4]. Sufficiently far from the Dirac energy and at sufficiently small concentrations the semi-classical theory is a good approximation. Near the Dirac energy we identify different quantum regimes, where the conductivity presents universal behaviours.

The understanding of the remarkable transport properties of quasicrystals is a long standing question. We have performed numerical studies on quantum diffusion in two dimensional Penrose tiling and octagonal tillings. Results show that long range quasiperiodic order induces a sub-diffusive regime at some energies in perfect tilings. In approximants, this unusual transport in analyse in term of Boltzmann (semi-classical) and non-Boltzmann contributions to the conductivity [6].

[1] G. Trambly de Laissardière, D. Mayou and L. Magaud, Nano Lett. 10, 804 (2010).
[2] G. Trambly de Laissardière, D. Mayou and L. Magaud,
Phys. Rev. B 86, 125413 (2012).
[3] I. Brihuega, P. Mallet, H. González-Herrero, G. Trambly de Laissardière, M. M. Ugeda, L. Magaud, J. M. Gómez-Rodríguez, F. Ynduráin, J.-Y. Veuillen,
Phys. Rev. Lett. 109, 196802 (2012).
[4] G. Trambly de Laissardière, D. Mayou, Mod. Phys. Lett. B 25, 1019-1028 (2011)
[5] G. Trambly de Laissardière, D. Mayou, Phys. Rev. Lett. 111, 146601 (2013).
[6] G. Trambly de Laissardière, C. Oguey, D. Mayou, Phil. Mag. 91, 2778-2786 (2011).


v. 27 Nov 2013