  The current-driven motion of magnetic domain walls (DWs) is the working
principle of magnetic racetrack memories. In this type of spintronic
technology, high current densities are used to propel DW motion in magnetic
nanowires, causing significant wire heating. Synthetic antiferromagnets are
known to show very fast DW motion at high current densities, but lower current
densities around onset of motion have received less attention. Here we use
scanning transmission x-ray microscopy to study the response of DWs in a SAF
multilayer to currents. We observe that the DWs depin at $\sim 3 \times
10^{11}$~A/m$^2$ and move more quickly in response to 5~ns duration current
pulses than in comparable conventional multilayers. The results suggest that
DWs in SAF structures are superior to conventional N\'{e}el DWs for low energy
consumption racetrack technologies.
