Growth and characterization of NbN/SmCo5 bilayers: the influence of magnetic stray field on the upper critical field of the superconductor

The coexistence of superconductivity (sc) and ferro-magnetism (fm) in artificially grown heterostructures, sc/fm-bilayers in the simplest case, leads to new interesting phenomena like domain-, domainwall-superconductivity and strayfield-effects. The intermetallic permanent magnet SmCo5 is especially known for its large magnetic anisotropy energy. Thin films of SmCo5 can be prepared with extremly high coercity fields: > 3T (at room temperature) and > 6T (at 10 K). to investigate the influence of the magnetic stray field on a conventional superconductor, NbN layers have been grown on SmCo5 thin films using pulsed laser deposition. the hybrid structures were investigated by x-ray diffraction and EDX. The magnetic properties were determined by VSM measurements. The angle-dependent upper critical field, Hc(2), and the accompanying magnetic effects of the superconducting/ferromagnetic hybrid were investigated in detail by standard four-probe technique.