A theoretical description of magnetic switching experiments in picosecond field pulses

Siegmann et nl. have reported that the magnetization in a perpendicularly oriented CoPt film with a uniaxial anisotropy field of 20 000 Oe was reversed when the film was exposed to a 20 000 Oe in-plane pulsed field lasting only 6 ps. From a calculation based on the Gilbert form of the Landau-Lifshitz equation (LLG), it is shown that the experimental result is consistent with the LLG model even for values of the damping constant a as larger as 0.5. The dependence of the switching time on the anisotropy field and the applied field are presented as a function of alpha and the angle beta between the applied field and the easy axis. Experiments are suggested which could illuminate the damping mechanism at these very short times. (C) 1996 American Institute of Physics.