Dynamic imaging of the delay- and tilt-free motion of Néel domain walls in perpendicularly magnetized superlattices

We report on the time-resolved investigation of current- and field-induced domain wall motion in the flow regime in perpendicularly magnetized microwires exhibiting anti-symmetric exchange interaction by means of scanning transmission x-ray microscopy using a time step of 200 ps. The sub-ns time step of the dynamical images allowed us to observe the absence of incubation times for the motion of the domain wall within an uncertainty of 200 ps, together with indications for a negligible inertia of the domain wall. Furthermore, we observed that, for short current and magnetic field pulses, the magnetic domain walls do not exhibit a tilting during its motion, providing a mechanism for the fast, tilt-free, current-induced motion of magnetic domain walls.