Spin-triplet supercurrent in Co/Ni multilayer Josephson junctions with perpendicular anisotropy

We have measured spin-triplet supercurrent in Josephson junctions of the form S/F'/F/F'/S, where S is superconducting Nb, F' is a thin Ni layer with in-plane magnetization, and F is a Ni/[Co/Ni](n) multilayer with out-of-plane magnetization. The supercurrent in these junctions decays very slowly with F-layer thickness and is much larger than in similar junctions not containing the two F' layers. Those two features are the characteristic signatures of spin-triplet supercurrent, which is maximized by the orthogonality of the magnetizations in the F and F' layers. Magnetic measurements confirm the out-of-plane anisotropy of the Co/Ni multilayers. These samples have their critical current optimized in the as-prepared state, which will be useful for future applications. DOI: 10.1103/PhysRevB.86.224506