Influence of pulse amplitude and rise time on field-induced domain wall propagation in Ni80Fe20 nanowires

Abstract

We have studied the field-induced propagation of domain walls (DWs) in magnetic nanowires by time-resolved magneto-optical Kerr microscopy. Magnetic field pulses with variable field amplitude lead to a DW velocity up to 500 m/s in 750 nm wide Ni80Fe20 nanowires, exceeding many other previous time-resolved optical measurements. Experiments show a linear relation between DW velocity and magnetic field beyond the Walker breakdown field, in agreement with micromagnetic simulations. In these simulations, the oscillation of DW type between vortex and transverse type, beyond Walker breakdown, is visualized. Furthermore, we experimentally show that the magnetic field pulse rise time is an important parameter for characterizing the DW velocity. Different pulse rise times lead to different injected DW types and DW velocities. These transient effects are especially important in possible future devices, where an ultrafast dynamical response of the DW is desired.