Highly transparent superconducting-normal junctions induced by local fields of magnetic domains in a homogeneous superconductor

Using the highly inhomogeneous fields of a magnetic substrate, tunable junctions between superconducting and normal-state regions were created inside a thin-film superconductor. The investigation of these junctions, created in the same material, gave evidence for the occurrence of Andreev reflection, indicating the high transparency of interfaces between superconducting and normal-state regions. For the realization of this study, a ferromagnet with magnetic-stripe domains was used as a substrate, on top of which a superconducting transport bridge was prepared perpendicular to the underlying domains. The particular choice of materials allowed to restrict the nucleation of superconductivity to regions above either reverse domains or domain walls. Moreover, due to the specific design of the sample, transport currents in the superconductor passed through a sequence of normal and superconducting regions.