Upper critical fields in granular superconductors

Journal Article · Sat Nov 01 04:00:00 EST 1980 · Phys. Rev., B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.22.4264· OSTI ID:6971291

Deutscher, G; Entin-Wohlman, O; Shapira, Y

We have measured the upper critical field in granular Al-Ge samples, as a function of temperature and for different metal concentrations. For small metal concentrations, we find that the upper critical field of the sample is that of the isolated grains at all temperatures. For high metal concentrations, the upper critical field is that of a bulk dirty superconductor. For intermediate metal concentrations, one observes a crossover from the bulk type-II behavior at high temperatures to the isolated grain behavior at low temperatures, with an upturn of the critical field at the crossover temperature. We present a Landau-Ginzburg model for the critical fields in a granular system and show that it explains the experimental data.

• Research Organization: Department of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
• OSTI ID: 6971291
• Journal Information: Phys. Rev., B: Condens. Matter; (United States), Journal Name: Phys. Rev., B: Condens. Matter; (United States) Vol. 22:9; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
ALUMINIUM ALLOYS
CRITICAL FIELD
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
GERMANIUM ALLOYS
GINZBURG-LANDAU THEORY
GRAIN SIZE
MAGNETIC FIELDS
MICROSTRUCTURE
PHYSICAL PROPERTIES
QUANTITY RATIO
SIZE
SUPERCONDUCTIVITY
TEMPERATURE DEPENDENCE