  Magnetic skyrmions are chiral spin textures that hold great promise as
nanoscale information carriers. Since their first observation at room
temperature, progress has 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 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 by micromagnetic
simulations including material inhomogeneities. This good agreement is enabled
by the simple skyrmion spin structure in our system and a thorough
characterization of its static and dynamical properties.
