1111.5233 (John R. Clem et al.)

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

John R. Clem, Yasunori Mawatari, G. R. Berdiyorov, F. M. Peeters

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.

View original: http://arxiv.org/abs/1111.5233