Valence charge fluctuations in YBa/sub 2/Cu/sub 3/O/sub 7-//sub delta/ from core-level spectroscopies
From x-ray photoemission and Auger measurements of the Cu 2p and O 1s core levels of YBa/sub 2/Cu/sub 3/O/sub 7-//sub delta/ as a function of the oxygen concentration delta, the average copper charge is determined. Evidence is found of dynamic charge fluctuations on the oxygen sublattice giving rise to a greater concentration of trivalent copper at the Cu(1) sites with respect to that determined by the analysis of neutron-diffraction data. On the basis of our experimental results, we introduce a molecular cluster description for the Cu states. The lowest final-states configurations of Cu/sup 2+/ and Cu/sup 3+/ are c3d/sup 10/L and c3d/sup 10/L/sup 2/, respectively, where c and L denote core holes on copper and oxygen atoms. Oxygen holes have high mobility and a Hubbard correlation energy less than 2 eV, a signature of their delocalization. The effect of temperature on the spectra is minor. Surface degradation modifies the relative intensity of the structures, particularly those of the O spectrum.
- Research Organization:
- Dipartimento di Fisica, Universita degli Studi di Roma II, via Orazio Raimondo, I-00173 Roma, Italy
- OSTI ID:
- 6934482
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Vol. 38:10
- Country of Publication:
- United States
- Language:
- English
Similar Records
Oxygen-stoichiometry dependence of the electronic structure of YBa/sub 2/Cu/sub 3/O/sub 7/. sqrt. /sub delta/ with delta(0
Valence-electron states of YBa sub 2 Cu sub 3 O sub 7 minus. delta. characterized by combined x-ray and photoemission studies
Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BARIUM OXIDES
ELECTRONIC STRUCTURE
HOLE MOBILITY
COPPER OXIDES
YTTRIUM OXIDES
AUGER ELECTRON SPECTROSCOPY
CHEMICAL COMPOSITION
CRYSTAL STRUCTURE
OXYGEN
PHOTOEMISSION
TEMPERATURE DEPENDENCE
VALENCE
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
ELECTRON SPECTROSCOPY
ELEMENTS
EMISSION
MOBILITY
NONMETALS
OXIDES
OXYGEN COMPOUNDS
SECONDARY EMISSION
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies
360204 - Ceramics
Cermets
& Refractories- Physical Properties
656100 - Condensed Matter Physics- Superconductivity