Figure 3: Domain wall transformation above the Walker breakdown.
From: Correlation between spin structure oscillations and domain wall velocities
A series of time-resolved STXM snapshots at times t=150, 164, 178, 186 and 200 ns during a 5 MHz rotational field burst pulse with an amplitude of B=6.8 mT. The rings are 750 nm wide, 30 nm thick and have a radius of (a) r=2 μm and (b) r=2.5 μm. The scale bar indicates a distance of 1 μm. (a) Between t=164 and 186 ns, the vortex core with positive polarity p=+1 is pushed towards the outer edge of the ring structure. However, no domain wall transformation to the transverse wall spin structure occurs, and therefore, the domain wall propagates below the Walker breakdown. (b) At the same field-rotation frequency, but in a ring structure with larger radius, the vortex core is expelled at t=178 ns, such that the vortex domain wall transforms into a transverse domain wall. The vortex core then renucleates within 8 ns at the outer edge of the ring with positive vortex core polarity.
