Figure 3: Dynamic behaviour of a magnetic skyrmion induced by bipolar pulse injections.

(a) Schematic of the Pt/CoFeB/MgO magnetic wire on the Si₃N₄ membrane with electrode contacts. The skyrmions are stabilized in the magnetic wire at B_z=12.5 mT. The inset shows an initial skyrmion used for the dynamic measurement. (b) Pulse profile used for the dynamics measurement. There is a time delay between each bipolar pulse and the incident X-ray beam pulse, which are injected at a frequency of f=3.33 MHz. The coloured circles and time numbers, t1–t10, in this plot indicate the time delay, which is also shown in following images. Magnetic skyrmion configuration at different time delays for voltage amplitudes of (c) V_a=2 V and (d) V_a=2.5 V, respectively. Horizontal lines are drawn in c,d to more effectively show the variation of the skyrmion. Scale bar, 200 nm. (e) Measured skyrmion diameter and (f) total skyrmion travel distance as a function of pulse delay time, respectively. Arrows are included in e to indicate the direction and magnitude of electron flow at each time delay, and a schematic drawing is also included on the right side to more clearly show the skyrmion motion direction relative to the electron flow direction. The actual pulse profile, shown in b, is also included in both plots to effectively show the response of skyrmion to time-dependent pulses. Error bars in e,f indicate the spatial resolution of beamline, ∼25 nm.