Predicted field-dependent increase of critical currents in asymmetric superconducting nanocircuits

The critical current of a thin superconducting strip of width W much larger than the Ginzburg-Landau coherence length [xi] but much smaller than the Pearl length [Lambda] = 2[lambda] super(2)/d is maximized when the strip is straight with defect-free edges. When a perpendicular magnetic field is app...

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Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2012-04, Vol.85 (14), Article 144511
Main Authors: Clem, John R., Mawatari, Yasunori, Berdiyorov, G. R., Peeters, F. M.
Format: Article
Language:English
Subjects:
Asymmetry
Condensed matter
Corners
Fluid flow
Magnetic fields
Mathematical analysis
Strip
Superconductivity
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Summary:The critical current of a thin superconducting strip of width W much larger than the Ginzburg-Landau coherence length [xi] but much smaller than the Pearl length [Lambda] = 2[lambda] super(2)/d is maximized when the strip is straight with defect-free edges. When a perpendicular magnetic field is applied to a long straight strip, the critical current initially decreases linearly with H but then decreases more slowly with H when vortices or antivortices are forced into the strip. However, in a superconducting strip containing sharp 90[degrees] or 180[degrees] turns, the zero-field critical current at H = 0 is reduced because vortices or antivortices are preferentially nucleated at the inner corners of the turns, where current crowding occurs. Using both analytic London-model calculations and time-dependent Ginzburg-Landau simulations, we predict that in such asymmetric strips the resulting critical current can be increased by applying a perpendicular magnetic field that induces a current-density contribution opposing the applied current density at the inner corners. This effect should apply to all turns that bend in the same direction.
ISSN:1098-0121
1550-235X
DOI:10.1103/PhysRevB.85.144511