Mesoscopic field and current compensator based on a hybrid superconductor-ferromagnet structure

A rather general enhancement of superconductivity is demonstrated in a hybrid structure consisting of a submicron superconducting (SC) sample combined with an in-plane ferromagnet (FM). The superconducting state resists much higher applied magnetic fields for both perpendicular polarities, as the applied field is screened by the FM. In addition, FM induces (in the perpendicular direction to its moment) two opposite currents in the SC plane, under and aside the magnet, respectively. Because of the compensation effects, superconductivity persists up to higher applied currents. With increasing current, the sample undergoes SC-"resistive"-normal state transitions through a mixture of vortex-antivortex and phase-slip phenomena.