X-ray photoelectron investigation of the valence-band electronic structure of superconducting Y-Ba-Cu oxide

Journal Article · Mon Aug 01 00:00:00 EDT 1988 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.38.2444· OSTI ID:6978857

Frommer, M H

The valence-band electronic structure of single-phase YBa/sub 2/Cu/sub 3/O/sub 7-//sub delta/ orthorhombic (superconducting) and tetragonal (nonsuperconducting) materials was studied at room temperature using x-ray photoelectron spectroscopy. The valence-band (VB) data have very clearly resolved spectral features and appear to yield more information than the core-level spectra which are hybrid states of combined Cu 2p, Cu 3d, and O 2p states. The difference in the density of states (DOS) is striking in that the orthorhombic material has a significant peak at an energy corresponding to bare Cu 3d/sup 8/ holes (Cu/sup 3+/ sites), whereas the tetragonal material has a very much smaller contribution at that energy. In the main part of the VB there is a shift of the maximum in the DOS away from E/sub f/ for the orthorhombic material with respect to the tetragonal. The DOS near E/sub f/ is lower for the former material compared to the latter. When this region is resolved into component peaks the results correspond to Cu 3d/sup 9/L and Cu 3d/sup 10/L/sup 2/ holes, where L is the ligand or O hole(s), which arise from the hybridization of Cu 3d and O 2p states. These are therefore not bare d holes but represent holes screened by O-to-Cu charge transfer. The data are in very good agreement with a configuration-interaction calculation for a CuO/sub 6//sup 10-/ cluster by Fujimori et al., both in shape and energies. The increased participation of oxygen in the VB of orthorhombic material is observed.

• Research Organization: Philips Laboratories, North American Philips Corporation, Briarcliff Manor, New York 10510
• OSTI ID: 6978857
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Vol. 38:4
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BARIUM OXIDES
ELECTRONIC STRUCTURE
COPPER OXIDES
YTTRIUM OXIDES
CONFIGURATION INTERACTION
ENERGY-LEVEL DENSITY
HYBRIDIZATION
MEDIUM TEMPERATURE
ORTHORHOMBIC LATTICES
PHOTOELECTRON SPECTROSCOPY
SUPERCONDUCTORS
TETRAGONAL LATTICES
X RADIATION
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
ELECTROMAGNETIC RADIATION
ELECTRON SPECTROSCOPY
IONIZING RADIATIONS
OXIDES
OXYGEN COMPOUNDS
RADIATIONS
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties
656100 - Condensed Matter Physics- Superconductivity