Domain wall motion at low current density in a synthetic antiferromagnet nanowire

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 that corresponds to wasted energy. 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 short current pulses. We observe that the DWs depin at (3.5 +/- 0.4) x10(11) A m(-2) and move more quickly in response to 5 ns duration current pulses than in comparable multilayers that lack antiferromagnetic coupling. The results suggest that DWs in SAF structures are superior to conventional Neel DWs for low energy consumption racetrack technologies.

Automated summary

The use of high current densities in magnetic racetrack memories results in significant wire heating and wasted energy. Synthetic antiferromagnets have shown fast domain wall (DW) motion at high current densities, but the behavior at lower current densities has received less attention. By using scanning transmission x-ray microscopy, this study found that DWs depin at (3.5 +/- 0.4) x10(11) A m(-2) and show faster motion in response to 5 ns duration current pulses compared to multilayers without antiferromagnetic coupling. These results suggest that DWs in synthetic antiferromagnets are superior for low energy consumption racetrack technologies.