VietNam 2013 

IXth Rencontres du Vietnam
Quy-Nhon, August 4-10, 2013

 QNplage

 Nanophysics: from fundamentals to applications

(the return)

 

Wednesday 7
Graphene

› 15:50 - 16:10 (20min)
Supercollision cooling of electrons in graphene
Bernard Plaçais  1@  , Andreas Betz  1@  , Sungho Jhang  1@  , Emiliano Pallecchi  2@  , Robson Ferreira  1@  , Gwendal Feve  1@  , Jean-Marc Berroir  1@  
1 : Laboratoire Pierre Aigrain  (LPA)  -  Website
CNRS : UMR8551, Université Pierre et Marie Curie (UPMC) - Paris VI, Université Paris VII - Paris Diderot, Ecole Normale Supérieure de Paris - ENS Paris
Département de Physique Ecole Normale Supérieure 24, rue Lhomond F-75231 Paris Cedex 05 -  France
2 : Laboratoire de photonique et de nanostructures  (LPN)
CNRS : UPR20
Route de Nozay 91460 MARCOUSSIS -  France

We have investigated the electron-lattice cooling rate in graphene by means of GHz Johnson noise thermometry. For phonon temperatures (Tph) larger than Bloch-Gruneisen temperature (TBG), we find the energy relaxation rate obeys a cubic law as a function of electron temperature. In this regime, the small Fermi surface of graphene drastically restricts the allowed phonon energy in ordinary electron-phonon scattering, and disorder-assisted supercollisions dominate over the conventional electron-phonon collisions. In the low-temperature regime, for Tph< TBG, we regain a Te^4 dependence, which is the signature of standard electron-phonon interaction in 2D graphene. Beside its implication for electron-phonon physics, our observations are of direct relevance for the performance of graphene bolometers and photo-detectors.


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