Magnetization Reversal of Highly Coercive FePt Examined With Pulsed Microcoils

The switching of ultra-high coercivity FePt thin films has been studied by pulsed magnetic fields of up to 25 T, generated with microcoils of 50 mum diameter and using a fast magneto-optical polar Kerr effect setup. Whereas under static measurements, the coercive field reaches 5.5 T, under pulsed magnetic field it approaches 8 T. An approximation of the Landau-Lifshitz-Gilbert (LLG) equation was used to calculate the magnetization response to the field pulse. Good agreement between experiment and simulation is observed if a value of 0.1 is assumed for the damping constant