Temperature dependence of positron annihilation parameters in Tl-Ba-Ca-Cu-O superconductors

Journal Article · Wed Aug 01 04:00:00 EDT 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.42.2193· OSTI ID:6338900

Sundar, C S; Bharathi, A; Ching, W Y; Jean, Y C ^[1]; Hor, P H; Meng, R L; Huang, Z J; Chu, C W ^[2]

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1. University of Missouri-Kansas City, Kansas City, MO (USA)
2. Texas Center for Superconductivity, University of Houston, Houston, TX (USA)

The results of positron lifetime and Doppler broadened line-shape parameter measurements as a function of temperature, across {Tc}, in the Tl-Ba-Ca-Cu-O superconductors are presented. The bulk lifetime in the normal state is found to decrease with the increase in the number of CuO{sub 2} layers. Different temperature dependencies of the annihilation parameters are observed in the various Tl systems containing different numbers of CuO{sub 2} layers. In the Tl{sub 2}Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} system, an increase in lifetime is observed below {Tc}, whereas in Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8}, a decrease in lifetime is seen below {ital T}{sub {ital c}}. In the Tl{sub 2}Ba{sub 2}CuO{sub 6} system, the lifetime is observed to be temperature independent. The different temperature variations of positron annihilation parameters are discussed in the light of the positron density distribution, obtained with use of the results of the self-consistent orthogonalized linear combination of atomic orbitals band-structure calculations. It is argued that the different temperature dependencies of the annihilation parameters is related to the positron density distribution within the unit cell and arise due to local charge transfer in the vicinity of the CuO{sub 2} layer in the superconducting state.

• OSTI ID: 6338900
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 42:4; ISSN PRBMD; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
656003 -- Condensed Matter Physics-- Interactions between Beams & Condensed Matter-- (1987-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
ANNIHILATION
BARIUM COMPOUNDS
BARIUM OXIDES
BASIC INTERACTIONS
CALCIUM COMPOUNDS
CALCIUM OXIDES
CHALCOGENIDES
CHARGE TRANSPORT
COLLISIONS
COPPER COMPOUNDS
COPPER OXIDES
DOPPLER BROADENING
ELECTROMAGNETIC INTERACTIONS
HIGH-TC SUPERCONDUCTORS
INTERACTIONS
LIFETIME
LINE BROADENING
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POSITRON COLLISIONS
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
THALLIUM COMPOUNDS
THALLIUM OXIDES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE