Flipping magnetic vortex cores on the picosecond time scale

We present a mechanism for reversing magnetic vortex cores with ultrashort field pulses. Using fully three-dimensional micromagnetic simulations, we show the details of the core reversal mechanism, which unfolds within a few tens of picoseconds. We investigate the stability of this process with respect to the angle at which the external field is applied, and for the case when strong fields are applied perpendicularly to the sample plane. The understanding of the vortex core dynamics represents a further step towards the controlled ultrafast switching of nanomagnets.