Positron annihilation in superconducting 123 compounds

Conference · Sun Dec 20 00:00:00 EST 1998 · International Journal of Modern Physics B

OSTI ID:6334441

Peter, M; Manuel, A A; Erb, A ^[1]

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1. Univ. of Geneva (Switzerland). Dept. of Physics of Condensed Matter

After a brief review of the theory of angular correlation of positron annihilation radiation (ACAR), the authors illustrate experimental principles and give examples of successful determination of electron momentum density (EMD) and of positron lifetime in solids. The central question which the authors try to answer concerns the contribution of positron spectroscopy to the knowledge and understanding of the new high temperature superconducting oxides. They find that in these oxides also, partially filled bands exist and they can observe parts of their Fermi surface and measure lifetimes in accordance with band theoretical calculations. There are characteristic differences, however. The intensity of the anisotropy of the ACAR signal is below theoretical expectation and signals depend on sample preparation. Recent studies by the Geneva group have concerned dependence of the signals on impurities, on oxygen content and on the thermal history of preparation. Of particular interest are correlations between the variations of these signals and between the variations of structural and transport properties in these substances. Besides deliberate additions of impurities, the Geneva group also reports progress in the preparations of samples of highest purity (barium zirconate crucibles). The alloy series Pr[sub x]Y[sub 1[minus]x]Ba[sub 2]Cu[sub 3]O[sub 7[minus][delta]] is of special interest because of exceptional transport properties. The recent positron results on these materials will be presented and commented in the light of theoretical models and in the light of the reported superconductivity of the Pr-compound.

• OSTI ID: 6334441
• Report Number(s): CONF-980291-; CODEN: IJPBEV
• Journal Information: International Journal of Modern Physics B, Vol. 12:29-31; Conference: 1. international conference on new theories, discoveries, and applications of superconductors and related materials, Baton Rouge, LA (United States), 19-24 Feb 1998; ISSN 0217-9792
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANNIHILATION
BARIUM OXIDES
COPPER OXIDES
CRYSTAL STRUCTURE
FERMI LEVEL
HIGH-TC SUPERCONDUCTORS
POSITRONS
PRASEODYMIUM OXIDES
SUPERCONDUCTIVITY
YTTRIUM OXIDES
ALKALINE EARTH METAL COMPOUNDS
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
BARIUM COMPOUNDS
BASIC INTERACTIONS
CHALCOGENIDES
COPPER COMPOUNDS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTROMAGNETIC INTERACTIONS
ELEMENTARY PARTICLES
ENERGY LEVELS
FERMIONS
INTERACTIONS
LEPTONS
MATTER
OXIDES
OXYGEN COMPOUNDS
PARTICLE INTERACTIONS
PHYSICAL PROPERTIES
PRASEODYMIUM COMPOUNDS
RARE EARTH COMPOUNDS
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
TYPE-II SUPERCONDUCTORS
YTTRIUM COMPOUNDS
360202* - Ceramics
Cermets
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360204 - Ceramics
Cermets
& Refractories- Physical Properties
665100 - Nuclear Techniques in Condensed Matter Physics - (1992-)