Interplay between interface structure and magnetism in NiFe/Cu/Ni-based pseudo-spin valves

Magnetic pseudo spin valves (PSVs) with superconducting Nb electrodes, have been leading candidates for an energy-efficient memory solution compatible with cryogenic operation of ultra-low power superconducting logic. Integration of these PSV Josephson junctions in a standard multi-layer Nb process requires growing high-quality thin magnetic films on a thick Nb bottom electrode (i.e. ≥1.5kA, to achieve bulk superconducting properties). However, as deposited, 1.5kA Nb exhibits a rough surface with a characteristic rice grain morphology, which severely degrades the switching properties of subsequently deposited PSVs. Therefore, in order to achieve coherent switching throughout a PSV, the Nb interface must be modified. Here, we demonstrate that the Nb surface morphology and PSV crystallinity can be altered with the incorporation of separate 50A Cu or 100A Al/50A Cu non-magnetic seed layers, and demonstrate their impact on the magnetic switching of a 15A Ni80Fe20/50A Cu/20A Ni PSV, at both room temperature an...