PHOTOELECTRON-SPECTRA OF THIN-FILMS OF THE HIGH-T-C SUPERCONDUCTOR YBA2CU3O7-DELTA

The results of calculations of the energy band structure of thin films are used to obtain theoretical photoelectron spectra of the valence b and of the compound YBa2Cu3O7-delta for delta=0 and delta=1 at various photon energies; the spectra are averaged over the photoelectron emis sion angles. The principal structural features of the spectra are dete rmined by the tt states of copper atoms, while the variation of the sh ape of the spectra with increasing photon energy is attributed to a re lative decrease in the contribution from the p states of oxygen atoms. The density of d states around the Fermi level for YBa2Cu3O6 films is observed to increase relative to YBa2Cu3O7 films. (C) 1997 American I nstitute of Physics.