Politique d`attribution des Allocations de Recherches - ED 397

'Physique et Chimie des Matériaux' – ED 397 – 2009
Proposition pour allocation de recherche, Thème (D):Nanostructures, nanomagnétisme,
spintronique
retour avant le 8 mai 2009 à [email protected], en format PDF
Unité: Institut de Minéralogie et de Physique des Milieux Condensés, IMPMC UMR7590
Adresse : 140 rue de Lourmel, Campus Boucicaut, 75015 Paris
Directeur de l’Unité : Bernard Capelle
Etablissement de rattachement : Université Pierre et Marie Curie (Paris 6)
Directeur de thèse: F. Mauri, Tel: 0144272764, E-mail: [email protected]
Co-encadrant éventuel : M. Lazzeri
TITRE: Coupled electron and thermal transport in graphene
Carbon-based nanomaterials such as carbon nanotubes, single-layer graphene sheets or graphene
nanoribbons are receiving much attention due to their unique properties and in view of possible
applications in future nano-ectronic devices. Since 2004, our group has been one of the leading players
in the characterization of the physical properties of these systems. In this period our group has
published more than 20 scientific papers on this topic (among them 9 PRL, 10 PRB and one Nature
materiasl) with a total number of 804 citations (165 in the first four months of 2009). As an example,
thanks to our results it is now possible to use Raman spectroscopy in order to determine the charge
doping in carbon nanotubes and graphene and the number of layers in a graphene sample [1]. This last
method has become the standard technique used by all the experimentalists working in the field. A list
of publications from our group on this topic can be found in
http://www.impmc.jussieu.fr/~lazzeri/carbon.html
We plan to study the coupled electronic and phononic transport in a graphene sample charged by a gate
voltage in a field-effect device configuration. The microscopic parameters involved in the transport
(electron-phonon, phonon-phonon, electron-defect and phonon-defect scatterings) are determined by
ab-initio computational methods based on density functional theory. The parameters thus obtained are
then used to describe the transport by means of Boltzmann or non-equilibrium Green function
approaches. We plan to study:
i) the high-bias (Voltage >0.2 Volts) electron transport. In this regime, the main source of resistence is
the coupling of electrons with optical phonons, through the same mechanism we already studied in
metallic nanotubes [2]. Preliminary results indicate that, however, in graphene the situation is more
complex since the accurate description of the eleastic scattering (due to defects and acoustic phonons)
is necessary to quantitatively reproduce measurements.
iii) Determination of the thermal transport properties. These are determined by phonons and their
understanding is necessary to conceive new device configurations to ameliorate the thermal dissipation
in nanoelectronic devices. The phonon-phonon scattering coefficients, necessary for this task, will be
computed ab-initio as in [3]. This part of the project is done within the framework of the project
PNANO-ACCATTONE, approved in 2008 (coordinator: F.Mauri).
The student will work in a group of several permanent researchers and Post-Docs. The theoretical work
will be done in strict collaboration with the experimental groups lead by A. Shukla (IMPMC, Paris) and
A. Bachtold (Barcellona).
[1] Phys. Rev. Lett. 97, 187401 (2006).
[2] Phys. Rev. Lett. 95, 236802 (2005); Phys. Rev. B 73, 165419 (2006).
[3] Phys. Rev. Lett. 99, 176802 (2007).
Connaissances et compétences requises :
Solid-state physics background. Programming skills. A certain flexibility to react to the newest results
and trends will be crucial for a succesful thesis.