Photoelectron spectra of YBa 2Cu 3O x ( x=6.9 and 6.0)

Abstract

Using synchrotron radiation, photoelectron energy distribution curves in the valence band region have been measured on sintered polycrystalline YBa 2Cu 3O 6.9 and YBa 2Cu 3O 6.0 at liquid nitrogen temperature. Spectra measured on scraped clean surfaces are found to be reproducible. Overall spectra shapes coincide with the energy-band density-of-states curves calculated by the full potential linear augmented plane wave method, provided the locations of the bands are shifted by 1.0 eV. The Fermi edge is recognized in YBa 2Cu 3O 6.9 but not in YBa 2Cu 3O 6.0. The step at the Fermi edge is about one fiftieth as high as the highest peak at 2.3 eV.