Suppression of superconductivity in high-temperature superconductors: Electronic-structure effects
The author studied the electronic structure of the copper oxide high-temperature superconductors RBa{sub 2}Cu{sub 3}O{sub 7-x}, where R = Eu and Y. The objective was to study the electronic state of the copper and oxygen ions as the system was chemically driven from the superconducting to the non-superconducting regime. Specifically, the oxygen content was reduced by adjusting the annealing conditions, Zn was substituted for Cu, and Pr and Ce were introduced as dopants on the rare-earth sites. Measurements of the Cu-1s and Cu-2p edge structure in high-T{sub c} superconducting compounds can be consistently interpreted by assuming Cu to be in a 2+ state. Unoccupied states of Cu-3d character were detected in these compounds. More important, measurements of the O-1s edge indicate empty states of O-2p symmetry exist at the Fermi level. When the oxygen content is reduced, and superconductivity is suppressed, there is clear evidence for the formation of Cu{sup 1+} ions. When Zn sufficient to suppress superconductivity is substituted for Cu there is little change in the electronic states of the Cu and O ions. Microprobe analysis of Pr-doped samples indicate that Pr is completely soluble in the Eu 1-2-3 compound.
- Research Organization:
- New York Univ., NY (USA)
- OSTI ID:
- 7198294
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHARGED PARTICLES
COPPER COMPOUNDS
COPPER IONS
CUPRATES
ELECTRONIC STRUCTURE
EUROPIUM COMPOUNDS
IONS
OXYGEN COMPOUNDS
OXYGEN IONS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
YTTRIUM COMPOUNDS