  Josephson junctions containing ferromagnetic materials are generating
interest for use in superconducting electronics and cryogenic memory.
Optimizing the performance of such junctions is an ongoing effort, requiring
exploration of a broad range of magnetic systems. Here we study supercurrent
transmission through Ni/Ru/Ni synthetic antiferromagnets, with the idea that
their magnetic properties may be superior to those of isolated Ni layers. We
find that the decay of the supercurrent as a function of Ni thickness is very
slow, with a decay length of 7.5 $\pm$ 0.8 nm. We also characterize the
magnetic properties of the synthetic antiferromagnets as a function of Ni and
Ru thicknesses.
