Pair breaking mechanisms in superconductor-normal metal-superconductor (SNS) junctions
Critical current density, J/sub c/, has been measured for Pb-Ag/sub 1-x-y/Mn/sub x/Al/sub y/-Pb junctions over a wide range of temperature and composition in order to determine the depairing effects of magnetic impurities. Junctions, which are in a sandwich geometry typically 200 to 1000 nm thick, show well-defined diffraction patterns indicating that the junctions are of high quality. The temperature dependence of J/sub c/ for samples containing magnetic impurities are found to follow a theory developed by Makeev et al. 1) for a bridge geometry. This then implies that for the sandwich geometry, the modulus of the order parameter at the boundary is proportional to its bulk value in the superconductor as was assumed by Makeev et al. In this range, xi/sub e/ is essentially independent of T, so this is a reasonable result. As T approaches T/sub c/, J/sub c/ was found to be proportional to (l-T/T/sub c/)/sup 2/ as predicted by the theories for the sandwich geometry. One junction which had a Mn concentration of about 0.5% and a spin glass temperature of 2.9K showed an inflection point in the J/sub c//sup (1/2)/ vs. T data near 2.7K. This change in slope may reflect a change in the spin scattering rate as the temperature falls through the spin glass temperature. If data are taken in the presence of a constant magnetic field, then quantum oscillations are observed. These oscillations arise from interference effect as successive quantized vortices enter the junctions.
- Research Organization:
- Iowa State Univ. of Science and Technology, Ames (USA)
- OSTI ID:
- 7026321
- Country of Publication:
- United States
- Language:
- English
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Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM
CRITICAL CURRENT
CRITICAL TEMPERATURE
CURRENT DENSITY
CURRENTS
DATA
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
ELEMENTS
EXPERIMENTAL DATA
HETEROJUNCTIONS
IMPURITIES
INFORMATION
JUNCTIONS
LEAD
MANGANESE
METALS
NUMERICAL DATA
PHYSICAL PROPERTIES
SEMICONDUCTOR JUNCTIONS
SILVER
SUPERCONDUCTING JUNCTIONS
SUPERCONDUCTIVITY
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS
TRANSITION TEMPERATURE