Abstract
We investigate the band structure of , an insulating parent compound of doped high- 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 breathing distortions. Though the distortions are often thought to coincide with 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 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 orbitals.
- Received 3 March 2016
DOI:https://doi.org/10.1103/PhysRevLett.117.037002
© 2016 American Physical Society