title: Hot electron cooling by acoustic phonons in graphene.
abstract: We have investigated the energy loss of hot electrons in metallic graphene by means of GHz noise thermometry at liquid helium temperature. We observe the electronic temperature T ∝ V at low bias in agreement with the heat diffusion to the leads described by the Wiedemann-Franz law. We report on T ∝ √V behavior at high bias, which corresponds to a T(4) dependence of the cooling power. This is the signature of a 2D acoustic phonon cooling mechanism. From a heat equation analysis of the two regimes we extract accurate values of the electron-acoustic phonon coupling constant Σ in monolayer graphene. Our measurements point to an important effect of lattice disorder in the reduction of Σ, not yet considered by theory. Moreover, our study provides a strong and firm support to the rising field of graphene bolometric detectors.
authors.affiliation: Laboratoire Pierre Aigrain, ENS-CNRS UMR, Universités P. et M. Curie and Paris-Diderot, France.
authors.forename: A C
authors.initials: AC
authors.lastname: Betz
authors.forename: F
authors.initials: F
authors.lastname: Vialla
authors.forename: D
authors.initials: D
authors.lastname: Brunel
authors.forename: C
authors.initials: C
authors.lastname: Voisin
authors.forename: M
authors.initials: M
authors.lastname: Picher
authors.forename: A
authors.initials: A
authors.lastname: Cavanna
authors.forename: A
authors.initials: A
authors.lastname: Madouri
authors.forename: G
authors.initials: G
authors.lastname: Fève
authors.forename: J-M
authors.initials: JM
authors.lastname: Berroir
authors.forename: B
authors.initials: B
authors.lastname: Plaçais
authors.forename: E
authors.initials: E
authors.lastname: Pallecchi