title: Direct view of hot carrier dynamics in graphene.
abstract: The ultrafast dynamics of excited carriers in graphene is closely linked to the Dirac spectrum and plays a central role for many electronic and optoelectronic applications. Harvesting energy from excited electron-hole pairs, for instance, is only possible if these pairs can be separated before they lose energy to vibrations, merely heating the lattice. Until now, the hot carrier dynamics in graphene could only be accessed indirectly. Here, we present a dynamical view on the Dirac cone by time- and angle-resolved photoemission spectroscopy. This allows us to show the quasi-instant thermalization of the electron gas to a temperature of ≈2000 K, to determine the time-resolved carrier density, and to disentangle the subsequent decay into excitations of optical phonons and acoustic phonons (directly and via supercollisions).
authors.affiliation: Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Jens Christian
authors.initials: JC
authors.lastname: Johannsen
authors.forename: Søren
authors.initials: S
authors.lastname: Ulstrup
authors.forename: Federico
authors.initials: F
authors.lastname: Cilento
authors.forename: Alberto
authors.initials: A
authors.lastname: Crepaldi
authors.forename: Michele
authors.initials: M
authors.lastname: Zacchigna
authors.forename: Cephise
authors.initials: C
authors.lastname: Cacho
authors.forename: I C Edmond
authors.initials: IC
authors.lastname: Turcu
authors.forename: Emma
authors.initials: E
authors.lastname: Springate
authors.forename: Felix
authors.initials: F
authors.lastname: Fromm
authors.forename: Christian
authors.initials: C
authors.lastname: Raidel
authors.forename: Thomas
authors.initials: T
authors.lastname: Seyller
authors.forename: Fulvio
authors.initials: F
authors.lastname: Parmigiani
authors.forename: Marco
authors.initials: M
authors.lastname: Grioni
authors.forename: Philip
authors.initials: P
authors.lastname: Hofmann