Superconducting properties of bismuthate/manganite epitaxial multilayers

We report epitaxial growth and superconducting properties of superconductor/ferromagnet (S/F) multilayers consisting of an s -wave superconducting bismuthate BaPb 0.75 Bi 0.25 O 3 (BPBO) and a ferromagnetic insulating manganite La 0.875 Sr 0.125 MnO 3 (LSMO). We demonstrate that the superconductivity of BPBO sandwiched by LSMO is preserved down to a thickness close to the superconducting coherence length. The superconducting transition temperature of BPBO is unaffected by the magnetization alignment of the LSMO layers, which is in sharp contrast to YBa 2 Cu 3 O 7 showing a clear magnetic exchange interaction. While the stable s -wave superconductivity in the S/F oxide multilayer demonstrated in this work is promising for the development of quantum spin devices with strong spin–orbit coupling, the absence of the magnetic exchange field effect highlights the importance of interface engineering for the realization of a strongly exchange-coupled s -wave S/F oxide interface.