Photoemission studies of single crystal CuO(100)

Photoemission studies of a cleaved CuO single crystal have been carried out, using station 6.2 at the CLRC Daresbury Laboratory. The (100) face orientation produced by anvil cleaving was determined using Laue back-reflection and LEED. Resonant photoemission measurements at the Cu 3p→Cu 3d threshold were undertaken and these are compared with existing data from oxidized copper films, and with theoretical configuration interaction calculations for the resonance process. Angle-resolved measurements of the valence band structure have also been performed at different photon energies along three crystal axes, and these are mapped onto the 3D structure of the monoclinic material. This allows general comparison with existing momentum-resolved calculations. The validity of comparisons with both localized and delocalized descriptions of the electronic structure of this highly correlated oxide is discussed.