Current-Driven Skyrmion Motion and Drive-Dependent Skyrmion Hall Effect in an Ultrathin Film

Magnetic skyrmions are chiral spin textures holding great potential as nanoscale information carriers. Since their first observations at room temperature, progresses have been made in their current-induced manipulation with fast motion reported in stray-field-coupled multilayers. However, the complex spin textures with hybrid chiralities and large power dissipation in these multilayers limit their practical implementation and the fundamental understanding of their dynamics. Here, we report on the current-driven motion of N\'eel skyrmions with diameters in the 100 nm range in an ultrathin Pt/Co/MgO trilayer. We find that these skyrmions can be driven at a speed of 100 m s$^{-1}$ and exhibit a drive-dependent skyrmion Hall effect, which is accounted for by the effect of pinning. Our experiments are well substantiated by an analytical model of the skyrmion dynamics as well as micromagnetic simulations including material inhomogeneities. This good agreement is enabled by the simple skyrmion spin structure in our system and an accurate characterisation of its static and dynamical properties.