Fast current-induced skyrmion motion in synthetic antiferromagnets

Magnetic skyrmions are topological magnetic textures that hold great promise as nanoscale bits of information in memory and logic devices. Although room-temperature ferromagnetic skyrmions and their current-induced manipulation have been demonstrated, their velocity has been limited to about 100 meters per second. In addition, their dynamics are perturbed by the skyrmion Hall effect, a motion transverse to the current direction caused by the skyrmion topological charge. Here, we show that skyrmions in compensated synthetic antiferromagnets can be moved by current along the current direction at velocities of up to 900 meters per second. This can be explained by the cancellation of the net topological charge leading to a vanishing skyrmion Hall effect. Our results open an important path toward the realization of logic and memory devices based on the fast manipulation of skyrmions in tracks. Editor’s summary Magnetic skyrmions—topologically protected spin textures—have shown promise as information carriers in spintronic devices. Although they can be manipulated with electric currents, their speeds in tracks tend to be limited by phenomena such as the skyrmion Hall effect, which deflects and damps the skyrmion motion. Pham et al. avoided this issue, typical of ferromagnets, by using an antiferromagnet instead. The synthetic antiferromagnetic material, fabricated by sputtering, was composed of two platinum/cobalt layers coupled through a thin layer of ruthenium. The authors used magnetic force microscopy to monitor the motion of skyrmions after current injections and measured skyrmion velocities of up to 900 meters per second along the current direction. —Jelena Stajic