Properties of superconducting thin-film microbridges
This work reports investigations upon the dependences of critical current and current phase relation on the dimensions of a superconducting thin-film microbridge. A model has been developed upon the Volkov's hyperbolic bridges and the Zaitsev's boundary conditions to calculate the spatial variation of the order parameter for given bridge dimensions. The results indicate that the rigid boundary conditions are good approximations to narrow bridges (W much less than L) only. The critical current density of the bridge has been calculated also as a function of the bridge dimensions. It is found that the critical current density of small bridges is enhanced above its mean field critical value due to the proximity effects of the banks. Very good agreement is found between the calculated enhancement of the critical current density and the experimental results. Direct measurements have been made on the current phase relation of indium bridges with width smaller than 0.6 ..mu..m. The difficulties due to the extra phase shifts from the series thin film electrodes are overcome by a specially designed double loop configuration which has an extra low effective inductance. It is found that the current phase relation of small bridges (W,L, < xi) is sinusoidal. When either one of the bridge dimensions becomes larger than xi, the current phase curve is screwed to the right. For narrow bridges with L > xi, the results agree with the predictions of rigid boundary calculations as expected by our model.
- Research Organization:
- State Univ. of New York, Stony Brook (USA)
- OSTI ID:
- 5092632
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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SUPERCONDUCTIVITY AND SUPERFLUIDITY
36 MATERIALS SCIENCE
INDIUM
JOSEPHSON JUNCTIONS
SUPERCONDUCTING FILMS
ELECTRIC BRIDGES
BOUNDARY CONDITIONS
CRITICAL CURRENT
CURRENT DENSITY
DIMENSIONS
EXPERIMENTAL DATA
MATHEMATICAL MODELS
NOISE
ORDER PARAMETERS
PHASE SHIFT
THEORETICAL DATA
TIN
CURRENTS
DATA
ELECTRIC CURRENTS
ELECTRICAL EQUIPMENT
ELEMENTS
EQUIPMENT
FILMS
INFORMATION
JUNCTIONS
METALS
NUMERICAL DATA
SUPERCONDUCTING JUNCTIONS
656102* - Solid State Physics- Superconductivity- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena- (-1987)
360104 - Metals & Alloys- Physical Properties