title: Momentum-Resolved Electronic Structure of the High-T_{c} Superconductor Parent Compound BaBiO_{3}.
abstract: We investigate the band structure of BaBiO_{3}, an insulating parent compound of doped high-T_{c} superconductors, using in situ angle-resolved photoemission spectroscopy on thin films. The data compare favorably overall with density functional theory calculations within the local density approximation, demonstrating that electron correlations are weak. The bands exhibit Brillouin zone folding consistent with known BiO_{6} breathing distortions. Though the distortions are often thought to coincide with Bi^{3+}/Bi^{5+} charge ordering, core level spectra show that bismuth is monovalent. We further demonstrate that the bands closest to the Fermi level are primarily oxygen derived, while the bismuth 6s states mostly contribute to dispersive bands at deeper binding energy. The results support a model of Bi-O charge transfer in which hole pairs are localized on combinations of the O 2p orbitals.
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
authors.forename: N C
authors.initials: NC
authors.lastname: Plumb
authors.affiliation: Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
authors.forename: D J
authors.initials: DJ
authors.lastname: Gawryluk
authors.affiliation: Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
authors.forename: Z
authors.initials: Z
authors.lastname: Ristić
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Park
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.|Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: B Q
authors.initials: BQ
authors.lastname: Lv
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.|Department of Quantum Matter Physics, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
authors.forename: C E
authors.initials: CE
authors.lastname: Matt
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
authors.forename: N
authors.initials: N
authors.lastname: Xu
authors.affiliation: Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Shang
authors.affiliation: Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
authors.forename: K
authors.initials: K
authors.lastname: Conder
authors.affiliation: Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.|Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.|Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Mesot
authors.affiliation: Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200, USA.
authors.forename: S
authors.initials: S
authors.lastname: Johnston
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Shi
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.|SwissFEL, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Radović