Cylindrical Josephson tunneling
Measurements of the Josephson tunneling current between thin cylindrical superconductors in an axial magnetic field are presented and compared with the theory which is developed in this dissertation. The essential idea is that the wave functions in the superconductors must be of the form psi/sub 1/ = /psi/sub infinity//f/sub 1/(r)e/sup in/1/sup theta/ and psi/sub 2/ = /psi/sub infinity//f/sub 2/(r)e/sup i/(/sup n//sub 2/theta + delta/sub 0/) to guarantee that they are single valued. This, together with the Josephson relation J = J/sub 0/ Sin delta, where J/sub 0/ is the maximum Josephson current and delta is the phase difference between the superconductors leads to the conclusion that the Josephson current will be zero for n/sub 1/ not equal to n/sub 2/. For n/sub 1/ = n/sub 2/, the current will be proportional to f/sup 2//sub 1/f/sup 2//sub 2/ in the thin film approximation. If the inner cylinder is solid and of higher transition temperature, then J/sub 0/ is proportional to f/sup 2//sub 2/ which provides a means for determining the order parameter as a function of axial magnetic field. The size of the cylinders relative to the coherence length and the penetration depth determines the variation of J/sub 0/ with magnetic field. Pairs of thin tin film cylinders were deposited on plastic optical fibers of 25 ..mu..m radius and quartz fibers of several sizes down to 3.5 ..mu..m radius. The inner tin film was oxidized in an oxygen glow discharge prior to the deposition of the second film. The Josephson currents decreased with field much as predicted by the theory but the cylinders were always in the same quantum states i.e., n/sub 1/ = n/sub 2/.
- Research Organization:
- Clemson Univ., SC (USA)
- OSTI ID:
- 5946336
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360104* -- Metals & Alloys-- Physical Properties
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COHERENCE LENGTH
CONFIGURATION
CURRENTS
CYLINDRICAL CONFIGURATION
DATA
DIMENSIONS
ELECTRIC CURRENTS
ELEMENTS
EXPERIMENTAL DATA
FILMS
INFORMATION
JOSEPHSON EFFECT
LENGTH
MAGNETIC FIELDS
METALS
NUMERICAL DATA
ORDER PARAMETERS
PENETRATION DEPTH
PHYSICAL PROPERTIES
SUPERCONDUCTING FILMS
THERMODYNAMIC PROPERTIES
TIN
TRANSITION TEMPERATURE