Magnetic skyrmions have significant potential for applications in storage and logic devices, but the ability to control skyrmion motion is key to their success. To realize controlled skyrmion motion, vertical spin current-driven methods employing, e.g., the spin Hall or inverse spin galvanic effect, are efficient; thus, magnetic heterostructures featuring large spin-orbit torques are appealing. In this paper, we report on the observation of room-temperature magnetic skyrmions in Pt/Co/W multilayers. The interfacial Dzyaloshinskii-Moriya interaction was estimated to be $0.19\pm 0.05\mathrm{mJ}/{\mathrm{m}}^2$ based on the asymmetric domain-wall motion occurring upon the application of in-plane magnetic fields. The evolution of the magnetic structures from labyrinth domains to skyrmions with diameters of around 145 nm under magnetic fields was observed by performing Lorentz transmission electron microscopy. The skyrmion nucleation fields could be tuned by varying the repetition number. Large spin Hall angle systems such as Pt/Co/W multilayers are appealing for achieving current-driven skyrmion motion in future racetrack and logic applications.

• Received 11 June 2018
• Revised 12 October 2018

DOI:https://doi.org/10.1103/PhysRevB.98.174425