Fig. 2: Current driven skyrmion motion.

Applied magnetic field-dependent current-pulse-driven skyrmion motion in 2-μm-wide Ta/Pt/[Pt/CoB/Ir]_×5/Pt multilayer wires. a Histogram of the skyrmion diameter distribution at each value of out-of-plane field. b Average diameter at each value of applied field. Standard error is plotted. As the field becomes more negative, the average diameter of the mobile skyrmions reduces until a critical field of −3 mT, at which point small skyrmions annihilate during the current pulse. The inset shows a trace of the current pulse applied from the top to the bottom of the wire. STXM images taken after two consecutive pulses separated by 2 μs capturing the skyrmion motion. c–l Initial state STXM single helicity images of the magnetic state in the wire (arrow in c indicates the applied current direction). Superimposed onto the images are the skyrmion centre positions after each two-pulse train (coloured symbols). The images were taken with in an out-of-plane field of 0, 0, −0.5, −1.0, −1.5, −2.0, −2.5, −3.0, −3.5, −3.5 and −4.0 mT, respectively. The peak current density was 5.6 × 10¹¹ Am⁻².