  Josephson junctions containing two ferromagnetic layers are being considered
for use in cryogenic memory. Our group recently demonstrated that the
ground-state phase difference across such a junction with carefully chosen
layer thicknesses could be controllably toggled between zero and $\pi$ by
switching the relative magnetization directions of the two layers between the
antiparallel and parallel configurations. However, several technological issues
must 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, rather
than in the Superconducting QUantum Interference Device (SQUID) used for the
phase-sensitive measurements. In this work, we report a comprehensive study of
spin-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 0.1
nm. We extract the field shift of the Fraunhofer patterns and the critical
currents of the junctions in the parallel and antiparallel magnetic states, as
well as the switching fields of both magnetic layers. We also report a partial
study of similar junctions containing a slightly thinner Ni layer of 1.6 nm and
the same range of NiFe thicknesses. These results represent the first step
toward mapping out a ``phase diagram" for phase-controllable spin-valve
Josephson junctions as a function of the two magnetic layer thicknesses.
