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 $\Lambda = 2 \lambda^2/d$ 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-degree or 180-degree 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 {\it 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. 
John R. Clem, Yasunori Mawatari, G. R. Berdiyorov, and F. M. Peeters
cond-mat.supr-con