Ultrafast stroboscopic time-resolved magneto-optical imaging of domain wall motion in Pt/GdFeCo wires induced by a current pulse

Fast and accurate current-driven manipulation of magnetic domain walls (DWs) is crucial for the realization of high-performance spintronic devices. Conventional methods to observe current-induced DW motion (CIDWM) require the accumulative measurement of magnetization dynamics, which is in general incompatible with stochastic magnetization dynamics. We demonstrate stroboscopic time-resolved imaging of CIDWM in a Pt/GdFeCo wire by electrically synchronizing the optical probe pulse and current injection pulse. The observed CIDWM dynamics unveil a time-varying DW velocity during the pulse, which can largely be attributed to the gradual temperature change due to Joule heating and an enhanced DW velocity at the angular momentum compensation temperature. The stroboscopic observation of DW dynamics was also utilized to investigate the contributions of inertial forces in CIDWM. Our method provides access to the spatial and stochastic magnetization dynamics in sophisticated structures driven by external stimuli and should be applicable to a wide range of current-driven phenomena.