Electronic structure near E sub F in YBa sub 2 Cu sub 3 O sub x for 6. 35 le x le 6. 9: A photoemission study

Journal Article · Sun Mar 01 00:00:00 EST 1992 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.45.5614· OSTI ID:5070802

Liu, R; Veal, B W; Paulikas, A P; Downey, J W; Shi, H ^[1]; Olson, C G; Gu, C ^[2]; Arko, A J; Joyce, J J ^[3]

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1. Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
2. Ames Laboratory and Department of Physics, Iowa State University, Ames, Iowa 50011 (United States)
3. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

High-resolution angle-resolved photoemission measurements are reported for YBa{sub 2}Cu{sub 3}O{sub {ital x}} when oxygen stoichiometries are in the range 6.35{le}{ital x}{le}6.9. The stoichiometry dependence of spectral features at energies close to the Fermi level was monitored along major symmetry lines in the two-dimensional Brillouin zone. Along {bar {Gamma}}-{ital {bar S}}, two bands dispersing through {ital E}{sub {ital F}} were observed in YBa{sub 2}Cu{sub 3}O{sub 6.9}. Band calculations indicate that these are plane''-related features. These two bands and the Fermi surfaces that they define are nearly independent of oxygen stoichiometry. The spectral weight near {ital E}{sub {ital F}} is relatively constant for 6.4{le}{ital x}{le}6.9. However, the spectral weight falls off significantly when {ital x}=6.35 (insulating), although the dispersive behavior that is characteristic of the higher oxygen stoichiometries persists. This abrupt intensity change might signal the onset of an electronic structure governed by strong correlation. Along {bar {Gamma}}-{ital {bar Y}}({ital {bar X}}), one band dispersing through {ital E}{sub {ital F}} was observed in YBa{sub 2}Cu{sub 3}O{sub 6.9}. As oxygen was removed, the intensity of this dispersive feature decreased systematically. Predictions of band theory indicate that this band is a chain''-related feature. In general, predictions of band theory appear to be quite reliable near {ital E}{sub {ital F}} in the oxygen stoichiometry range {ital x}{ge}6.4, where the material shows metallic behavior.

• DOE Contract Number: W-31-109-ENG-38; W-7405-ENG-82
• OSTI ID: 5070802
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 45:10; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
ELECTRONIC STRUCTURE
COPPER OXIDES
HIGH-TC SUPERCONDUCTORS
YTTRIUM OXIDES
BRILLOUIN ZONES
FERMI LEVEL
OXYGEN
PHOTOEMISSION
STOICHIOMETRY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
ELEMENTS
EMISSION
ENERGY LEVELS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
SECONDARY EMISSION
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
ZONES
360207* - Ceramics
Cermets
& Refractories- Superconducting Properties- (1992-)