Crossover between different regimes of inhomogeneous superconductivity in planar superconductor-ferromagnet hybrids

Abstract

We studied experimentally the effect of a stripelike domain structure in a ferromagnetic BaFe12O19 substrate on the magnetoresistance of a superconducting Pb microbridge. The system was designed in such a way that the bridge is oriented perpendicular to the domain walls. It is demonstrated that depending on the ratio between the amplitude of the nonuniform magnetic field B0, induced by the ferromagnet, and the upper critical field Hc2 of the superconducting material, the regions of the reverse-domain superconductivity in the H−T plane can be isolated or can overlap (H is the external magnetic field, T is temperature). The latter case corresponds to the condition B0/Hc2<1 and results in the formation of superconductivity above the magnetic domains of both polarities. We discovered the regime of edge-assisted reverse-domain superconductivity, corresponding to localized superconductivity near the edges of the bridge above the compensated magnetic domains. Direct verification of the formation of inhomogeneous superconducting states and external-field-controlled switching between the normal state and inhomogeneous superconductivity were obtained by low-temperature scanning laser microscopy.

Source-reported materials — not catalogue approval

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