Angle-resolved photoemission investigation of the electronic band properties ofYBa2Cu3O7−x(001)

The electronic energy-band properties of epitaxially grown YBa/sub 2/CuO/sub 3/O/sub 7-//sub x/(001) single-crystal thin films have been investigated by angle-resolved ultraviolet photoemission spectroscopy (ARUPS) with synchrotron radiation as the light source. The (001) surfaces exhibit sharp (1 x 1) low-energy electron-diffraction patterns. Our ARUPS data show a clear Fermi edge and dispersive nature of the valence bands, suggesting the validity of the band concept for this oxide. We determined energy-band dispersion along the GAMMA-X-M-GAMMA directions in the bulk Brillouin zone. The experimental results are compared with the existing ground-state band calculations.