Photoelectron spectra of thin films of the high-Tc superconductor YBa2Cu3O7−δ

The results of calculations of the energy band structure of thin films are used to obtain theoretical photoelectron spectra of the valence band of the compound YBa2Cu3O7−δ for δ=0 and δ=1 at various photon energies; the spectra are averaged over the photoelectron emission angles. The principal structural features of the spectra are determined by the d states of copper atoms, while the variation of the shape of the spectra with increasing photon energy is attributed to a relative 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.