Inhomogeneous magnetic fields generated by the ${\mathrm{BaFe}}_{12}{\mathrm{O}}_{19}$ ferromagnetic substrate create a magnetic template for superconducting condensate in the $\mathrm{Nb}∕{\mathrm{BaFe}}_{12}{\mathrm{O}}_{19}$ hybrids. Depending on the field and temperature, the magnetic template guides superconductivity to nucleate in different areas: above the magnetic domain walls of the ${\mathrm{BaFe}}_{12}{\mathrm{O}}_{19}$ forming the domain-wall superconductivity (DWS), above the reversed magnetic domains (RDS), and above the positive magnetic domains forming bulk superconductivity. The DWS, behaving as a superconducting wire network, survives in a broad field range. The RDS, existing in the form of isolated superconducting islands near the saturation field $H_s$ of ${\mathrm{BaFe}}_{12}{\mathrm{O}}_{19}$, can be described as a two-dimensional two-component random conductor mixture. Being related to the hysteretic domain evolution, superconducting condensate above the reversed domains shows pronounced switching behavior.

• Received 27 December 2005

DOI:https://doi.org/10.1103/PhysRevB.73.224509