Temperature dependence of positron-annihilation parameters in YBa/sub 2/Cu/sub 3/O/sub 7-//sub x/ above and below the superconducting transition
The temperature dependence of positron-annihilation parameters for YBa/sub 2/Cu/sub 3/O/sub 7-//sub x/ x = 0.7, 0.4, and 0.0 are reported. It was found that a transition in the Doppler line-shape parameter S was associated with the superconducting transition temperature (T/sub c/) in YBa/sub 2/Cu/sub 3/O/sub 7-//sub x/ x = 0.4 and 0.0, while no transition was observed in the nonsuperconducting YBa/sub 3/Cu/sub 3/O/sub 6.3/. Positron lifetime parameters in YBa/sub 2/Cu/sub 3/O/sub 7/ were found to be consistent with positrons localized at open volume regions (probably unoccupied crystallographic sites) in this material with a lifetime of 210 psec. The positron lifetime decreased by approximately 5% across the superconducting transition and subsequently by 4% to 193 +- 1 psec at 12 K. These results indicate that the electron density at this site increases approximately 9% between 100 and 12 K. Doppler line-shape results show that the average electron momentum at the annihilation site increases across the superconducting transition and from sample to sample as the oxygen concentration decreases.
- Research Organization:
- Department of Applied Science, Brookhaven National Laboratory, Upton, New York 11973
- OSTI ID:
- 5619430
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 36:16; ISSN PRBMD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
ANNIHILATION
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
BARIUM COMPOUNDS
BARIUM OXIDES
BASIC INTERACTIONS
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
DATA
ELECTROMAGNETIC INTERACTIONS
ELECTRON DENSITY
ELEMENTARY PARTICLES
EXPERIMENTAL DATA
FERMIONS
INFORMATION
INTERACTIONS
LEPTONS
LIFETIME
LOW TEMPERATURE
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POSITRONS
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
YTTRIUM COMPOUNDS
YTTRIUM OXIDES