Superconducting triplet pairing in Al/Al₂O₃/Ni/Ga junctions

Ni/Ga bilayers are a versatile playground for exploring the competition of the strongly antagonistic ferromagnetic and superconducting phases. Systematically characterizing this competition’s impact on highly ballistic Al/Al₂O₃/Ni/Ga junctions’ transport properties from both the experimental and theoretical viewpoints, we identify novel conductance peak structures, which are caused by superconducting triplet pairings at the Ni/Ga interface, and which are widely adjustable through the Ni–Ga thickness ratio. We demonstrate that these conductance anomalies persist even in the presence of an in-plane magnetic field, which provides—together with the detection of the paramagnetic Meissner effect in Ga—the clear experimental evidence that the observed conductance features serve indeed as the triplet pairings’ unique transport fingerprints. Our work demonstrates that Ni/Ga bilayers have a strong potential for superconducting spintronics applications, in particular for triplet-pairing engineering.