Soft x-ray absorption and emission spectra and the electronic structure of the Ba₂YCu₃O₇₋ₓ superconductor

We present e-beam-excited soft-x-ray emission spectra and total-photoelectron-yield spectra in the 20--600 eV photon energy range for Ba₂{YCu}₃O_7-x. In soft x-ray emission, the N₄,5 structure of Ba, the M₄,5 spectrum of Y, and the K spectrum of O provide a direct measure of the p-type partial density of states (p-PDOS) localized on the respective atomic sites. In each case the p-PDOS is very small at the Fermi energy εF. The maximum in the O K spectrum is 2.6±{}0.5 eV below εF. This result provides direct confirmation that the shoulder previously found at εF-2.3 eV in photoelectron emission spectra is associated with O p orbitals. No changes are observed between spectra taken above and below Tc. .AE