title: Parity of the pairing bosons in a high-temperature Pb-Bi2Sr2CaCu2O8 bilayer superconductor by angle-resolved photoemission spectroscopy.
abstract: We report the observation of a novel effect in the bilayer Pb-Bi2Sr2CaCu2O8 (Pb-Bi2212) high-T(c) superconductor by means of angle-resolved photoemission with circularly polarized excitation. Different scattering rates, determined as a function of energy separately for the bonding and antibonding copper-oxygen bands, strongly imply that the dominating scattering channel is odd with respect to layer exchange within a bilayer. This is inconsistent with a phonon-mediated scattering and favors the participation of the odd collective spin excitations in the scattering mechanism in near-nodal regions of the k space, suggesting a magnetic nature of the pairing mediator.
authors.affiliation: Leibniz-Institute for Solid State Research, IFW-Dresden, P.O. Box 270116, D-01171 Dresden, Germany.
authors.forename: S V
authors.initials: SV
authors.lastname: Borisenko
authors.forename: A A
authors.initials: AA
authors.lastname: Kordyuk
authors.forename: A
authors.initials: A
authors.lastname: Koitzsch
authors.forename: J
authors.initials: J
authors.lastname: Fink
authors.forename: J
authors.initials: J
authors.lastname: Geck
authors.forename: V
authors.initials: V
authors.lastname: Zabolotnyy
authors.forename: M
authors.initials: M
authors.lastname: Knupfer
authors.forename: B
authors.initials: B
authors.lastname: Büchner
authors.forename: H
authors.initials: H
authors.lastname: Berger
authors.forename: M
authors.initials: M
authors.lastname: Falub
authors.forename: M
authors.initials: M
authors.lastname: Shi
authors.forename: J
authors.initials: J
authors.lastname: Krempasky
authors.forename: L
authors.initials: L
authors.lastname: Patthey