Vortex shaking in superconducting platelets in an inclined magnetic field

Abstract

For thin superconducting platelets or films in a dc magnetic field, the application of a weak ac magnetic field in the plane of the platelet allows the vortices to drift. This vortex motion generates a dc voltage in the superconductor that causes the critical currents and irreversible magnetic moment to relax completely. This vortex shaking was explained quantitatively for long strips with weak ac field applied perpendicular or parallel to the critical screening currents that flow along the strip, and for films of rectangular shape. In all these cases the dc magnetic field was applied perpendicular to the film. The present work generalizes these theories to cases when the dc field is applied at an angle with respect to the film plane. It is found that an appropriate tilt of the dc field can strongly increase the anisotropy of the shaking-induced relaxation and accelerates the appearance of additional current loops, so that these effects may be observed more easily.