title: Anomalous Fermi-surface dependent pairing in a self-doped high-Tc superconductor.
abstract: We report the discovery of a self-doped multilayer high Tc superconductor Ba2Ca3Cu4O8F2 (F0234) which contains distinctly different superconducting gap magnitudes along its two Fermi-surface sheets. While formal valence counting would imply this material to be an undoped insulator, it is a self-doped superconductor with a Tc of 60 K, possessing simultaneously both electron- and hole-doped Fermi-surface sheets. Intriguingly, the Fermi-surface sheet characterized by the much larger gap is the electron-doped one, which has a shape disfavoring two electronic features considered to be important for the pairing mechanism: the van Hove singularity and the antiferromagnetic (pi/a, pi/a) scattering.
authors.affiliation: Department of Physics, Applied Physics, and Stanford Synchrotron Radiation Laboratory, Stanford University, Stanford, California 94305, USA.
authors.forename: Yulin
authors.initials: Y
authors.lastname: Chen
authors.forename: Akira
authors.initials: A
authors.lastname: Iyo
authors.forename: Wanli
authors.initials: W
authors.lastname: Yang
authors.forename: Xingjiang
authors.initials: X
authors.lastname: Zhou
authors.forename: Donghui
authors.initials: D
authors.lastname: Lu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Eisaki
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Devereaux
authors.forename: Zahid
authors.initials: Z
authors.lastname: Hussain
authors.forename: Z-X
authors.initials: ZX
authors.lastname: Shen