B. Sinkovic

Study of Magnetic Materials Using Spin-Resolved Circularly-Polarized Resonant Photoemission

We have recently demonstrated that it is possible to obtain spin-resolved valence band spectra with a very high degree of spin polarization from macroscopically non-magnetic transition metal materials if the excitation light is circularly polarized and has an energy close to the cation 2p3/2 (L3) white line. Using the layered compound Sr2CuO2Cl2 as a test system, we report in this paper that the degree of spin polarization is strongly dependent on the transition metal 3d orbital orientation relative to the Poynting vector of the light.

The electronic structure of YBa2Cu3O7−δ above and below Tc

The electronic structure of YBa2Cu3O7−δ has been investigated using synchrotron radiation above and below the superconducting transition temperature. Valence band spectra show a low density of states at the Fermi Level, a shift of the Cu3d‐O2p derived bands ∼1.5 eV below their calculated binding energy and a Cu 3p‐3d shake‐up satellite that suggest localization of the copper 3d‐states and also suggest that the copper ions have 2+ valence. Corelevel spectra also give evidence of the Cu2+ ion and show at least two distinct oxygen bonding environments. Cooling the surface to 20K, leaves the Cu and Ba corelevels unmodified, may produce a new O 1s corelevel component at 533 eV and causes a small change in the shape of the valence band. The Cu 3p‐3d satellite is weaker and increased photoemission coincident with states derived from the O 2p orbitals at the Cu 3p threshold is noted in the valence band. These changes upon cooling suggest that small changes in the Cu‐O electronic states occur and their possible re...