Occupied and unoccupied electronic states in layered-perovskite superconductor without copper: Band dispersions, van Hove singularity and hole states in Sr{sub 2}RuO{sub 4}
Book
·
OSTI ID:549848
- Forschungszentrum Karlsruhe (Germany). Inst. fuer Nukleare Festkoerperphysik
- IBM Research Div., Rueschlikon (Switzerland). Zuerich Research Lab.
The occupied and unoccupied electronic structure of high quality single crystals of the copper-free layered perovskite superconductor Sr{sub 2}RuO{sub 4} has been measured for the first time. Angle-resolved photoemission spectroscopy with high energy and angle resolution determined band dispersions along the principle directions of the projected Brillouin zone of the (001) surface. The highlight of these spectra is the observation and characterization of an extended van Hove singularity. The singularity is located 17 meV below the Fermi level and extends around the {bar M} point for around 0.2 {angstrom}{sup {minus}1} along both {bar {Lambda}}-{bar M}-{bar {lambda}} and {bar X}-{bar M}-{bar X}. Dispersions of the near-Fermi level states in Sr{sub 2}RuO{sub 4} reveal 3 bands which cross the Fermi level giving rise to 3 Fermi surfaces; 1 electron-like Fermi surface around the {bar {Lambda}} point and 2 hole-like surfaces encircling the {bar X} point. The topology of the empirically determined Fermi surfaces is found to be in qualitative agreement with Local Density Approximation band structure calculations. Photoemission of the full valence band of Sr{sub 2}RuO{sub 4} are also presented. The total valence band width is {approximately} 9 eV, the density of states at the Fermi level derived from photoemission is 1.3 states/(eV cell) and has a 80%/20% mix of metal to ligand character. Polarization-dependent O1s NEXAFS performed on Sr{sub 2}RuO{sub 4} demonstrate mainly hole states at the Fermi level in orbitals in the RuO{sub 2} planes. Electron correlations among Ru 4d levels in Sr{sub 2}RuO{sub 4} are argued to have a lesser impact than that of 3d levels in the cuprates.
- OSTI ID:
- 549848
- Report Number(s):
- CONF-960163--; ISBN 0-8194-2070-0
- Country of Publication:
- United States
- Language:
- English
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