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Unoccupied electronic states and surface phenomena for YBa/sub 2/Cu/sub 3/O/sub 6. 9/

Technical Report ·
OSTI ID:6231000
Inverse photoemission was used to probe the unoccupied electronic levels within 25 eV of E/sub F/ for the high temperature superconductor YBa/sub 2/Cu/sub 3/O/sub 6.9/. Our results show that the density of states is low from E/sub F/ to /approximately/3.7 eV. Large emission features appearing at 6.5 eV and 8.6 eV are associated with Ba 5d- and Y 4d-derived bands, respectively, while structure at 14 eV above E/sub F/ is due to localized Ba 4f states. Energy dependent studies reveal a dispersive band between /approximately/4 and /approximately/6 eV above E/sub F/. An oxygen- induced feature was observed at 1.8 eV, but there is no evidence that high-energy electron-stimulated-desorption removes these chemisorption states.
Research Organization:
Argonne National Lab., IL (USA)
DOE Contract Number:
W-31109-ENG-38
OSTI ID:
6231000
Report Number(s):
ANL/PPRNT-89-167; ON: DE89008356
Country of Publication:
United States
Language:
English