title: Terahertz radiation driven chiral edge currents in graphene.
abstract: We observe photocurrents induced in single-layer graphene samples by illumination of the graphene edges with circularly polarized terahertz radiation at normal incidence. The photocurrent flows along the sample edges and forms a vortex. Its winding direction reverses by switching the light helicity from left to right handed. We demonstrate that the photocurrent stems from the sample edges, which reduce the spatial symmetry and result in an asymmetric scattering of carriers driven by the radiation electric field. The developed theory based on Boltzmann's kinetic equation is in a good agreement with the experiment. We show that the edge photocurrents can be applied for determination of the conductivity type and the momentum scattering time of the charge carriers in the graphene edge vicinity.
authors.affiliation: Terahertz Center, University of Regensburg, Regensburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Karch
authors.forename: C
authors.initials: C
authors.lastname: Drexler
authors.forename: P
authors.initials: P
authors.lastname: Olbrich
authors.forename: M
authors.initials: M
authors.lastname: Fehrenbacher
authors.forename: M
authors.initials: M
authors.lastname: Hirmer
authors.forename: M M
authors.initials: MM
authors.lastname: Glazov
authors.forename: S A
authors.initials: SA
authors.lastname: Tarasenko
authors.forename: E L
authors.initials: EL
authors.lastname: Ivchenko
authors.forename: B
authors.initials: B
authors.lastname: Birkner
authors.forename: J
authors.initials: J
authors.lastname: Eroms
authors.forename: D
authors.initials: D
authors.lastname: Weiss
authors.forename: R
authors.initials: R
authors.lastname: Yakimova
authors.forename: S
authors.initials: S
authors.lastname: Lara-Avila
authors.forename: S
authors.initials: S
authors.lastname: Kubatkin
authors.forename: M
authors.initials: M
authors.lastname: Ostler
authors.forename: T
authors.initials: T
authors.lastname: Seyller
authors.forename: S D
authors.initials: SD
authors.lastname: Ganichev