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${}^{\circ }$ or 180${}^{\circ }$ 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.

• Received 22 November 2011

DOI:https://doi.org/10.1103/PhysRevB.85.144511