Electron energy loss spectroscopy of YBa2Cu3O7-x

Electronic excitations of Y-Ba-Cu-O polycrystalline material in superconducting form have been investigated by electron energy loss spectroscopy in reflection. The data obtained confirm recent band structure models for this material. Low electron energy losses correspond to energy levels close to the Fermi energy with an upper and lower Hubbard subband and an anionic O 2p band in the middle. Loss peaks due to interband transitions, plasmon excitations, and core electron excitations have been observed, the origin of which is interpreted by a schematic energy level diagram. (orig.)