Josephson junctions containing two ferromagnetic layers are being consideredfor use in cryogenic memory. Our group recently demonstrated that theground-state phase difference across such a junction with carefully chosenlayer thicknesses could be controllably toggled between zero and $\pi$ byswitching the relative magnetization directions of the two layers between theantiparallel and parallel configurations. However, several technological issuesmust be addressed before those junctions can be used in a large-scale memory.Many of these issues can be more easily studied in single junctions, ratherthan in the Superconducting QUantum Interference Device (SQUID) used for thephase-sensitive measurements. In this work, we report a comprehensive study ofspin-valve junctions containing a Ni layer with a fixed thickness of 2.0 nm,and a NiFe layer of thickness varying between 1.1 and 1.8 nm in steps of 0.1nm. We extract the field shift of the Fraunhofer patterns and the criticalcurrents of the junctions in the parallel and antiparallel magnetic states, aswell as the switching fields of both magnetic layers. We also report a partialstudy of similar junctions containing a slightly thinner Ni layer of 1.6 nm andthe same range of NiFe thicknesses. Unfortunately, current theoretical modelsof spin-valve Josephson junctions are not able to describe both data sets witha single set of fit parameters.
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