Carrier mobility in solids is generally limited by electron-impurity or electron-phonon scattering depending on the most frequently occurring event. Three body collisions between carriers and both phonons and impurities are rare; they are denoted supercollisions (SCs). Elusive in electronic transport they should emerge in relaxation processes as they allow for large energy transfers. As pointed out in Ref. \onlinecite{Song2012PRL}, this is the case in undoped graphene where the small Fermi surface drastically restricts the allowed phonon energy in ordinary collisions. Using electrical heating and sensitive noise thermometry we report on SC-cooling in diffusive monolayer graphene. At low carrier density and high phonon temperature the Joule power P obeys a P∝Te3 law as a function of electronic temperature Te. It overrules the linear law expected for ordinary collisions which has recently been observed in resistivity measurements. The cubic law is characteristic of SCs and departs from the Te4 dependence recently reported for metallic graphene below the Bloch-Gr\"{u}neisen temperature. These supercollisions are important for applications of graphene in bolometry and photo-detection.
@article{arxiv.1210.6894,
title = {Supercollision cooling in undoped graphene},
author = {A. C. Betz and S. H. Jhang and E. Pallecchi and R. Feirrera and G. Fève and J. -M. Berroir and B. Plaçais},
journal= {arXiv preprint arXiv:1210.6894},
year = {2013}
}