Retrieving pulse profiles from pump-probe measurements on magnetization dynamics

A method for back-tracing magnetic field pulses in pump-probe-type magnetization dynamics measurements is presented. Solving vectorially the Landau–Lifshitz–Gilbert equation for our field-induced measurement geometry yields field pulse profiles fulfilling the theoretical expectations on a 100 ps timescale. Applying the method to our earlier, all-optical-type pump-probe measurements, the claim that the optical pulse triggers an ultrafast anisotropy field pulse gets a direct proof: we derive a pulse consisting of a delta-peak type, full width at half maximum <5 ps impulse on top of a very fast rising step-like profile. Application of the method to other, less trivial pump-probe schemes can contribute to the development of novel type magnetic recording technologies.