Fabrication and characterization of ferromagnetic-superconducting hybrid films grown by combined PVD techniques

This study reports micro-fabricated magnet and superconductor (permalloy/Pb82Bi18) hybrid film structures sequentially grown by magnetron sputtering and thermal deposition techniques. 300 nm thick PbBi film was quench condensed on top of a patterned permalloy film. Permalloy film was sputtered and patterned to form few micrometer-wide stripes. Ferromagnetic and superconducting layers were separated by Al2O3 insulation. Transport superconducting properties, i.e. transition temperature TC(H) and second critical field HC2(T) were measured in a range of applied magnetic field between H = 0 and H = 7 kOe for the hybrid system and a control sample with only a layer of superconducting film deposited. The HC2(T) data showed that due to the interplay between the superconducting film and the ferromagnet, superconducting (SC) and normal current paths formed on the SC film.