Flux domes in superconducting films without edges

Original · EN

Domelike magnetic-flux-density distributions previously have been observed experimentally and analyzed theoretically in superconducting films with edges, such as in strips and thin plates. Such flux domes have been explained as arising from a combination of strong geometric barriers and weak bulk pinning. In this paper we predict that, even in films with bulk pinning, flux domes also occur when vortices and antivortices are produced far from the film edges underneath current-carrying wires, coils, or permanent magnets placed above the film. Vortex-antivortex pairs penetrating through the film are generated when the magnetic field parallel to the surface exceeds Hc₁+Kc, where Hc₁ is the lower critical field and Kc = jc d is the critical sheet-current density (the product of the bulk critical current density jc and the film thickness d). The vortices and antivortices move in opposite directions to locations where they join others to create separated vortex and antivortex flux domes. We consider a simple arrangement of a pair of current-carrying wires carrying current I₀ in opposite directions and calculate the magnetic-field and current-density distributions as a function of I₀ both in the bulk-pinning-free case (Kc = 0) and in the presence of bulk pinning, characterized by a field-independent critical sheet-current density (Kc > 0).