title: Weak-localization magnetoresistance and valley symmetry in graphene.
abstract: Because of the chiral nature of electrons in a monolayer of graphite (graphene) one can expect weak antilocalization and a positive weak-field magnetoresistance in it. However, trigonal warping (which breaks p-->-p symmetry of the Fermi line in each valley) suppresses antilocalization, while intervalley scattering due to atomically sharp scatterers in a realistic graphene sheet or by edges in a narrow wire tends to restore conventional negative magnetoresistance. We show this by evaluating the dependence of the magnetoresistance of graphene on relaxation rates associated with various possible ways of breaking a "hidden" valley symmetry of the system.
authors.affiliation: Department of Physics, Lancaster University, Lancaster, LA1 4YB, United Kingdom.
authors.forename: E
authors.initials: E
authors.lastname: McCann
authors.forename: K
authors.initials: K
authors.lastname: Kechedzhi
authors.forename: Vladimir I
authors.initials: VI
authors.lastname: Fal'ko
authors.forename: H
authors.initials: H
authors.lastname: Suzuura
authors.forename: T
authors.initials: T
authors.lastname: Ando
authors.forename: B L
authors.initials: BL
authors.lastname: Altshuler