Magnetization reversal in magnetic nanostructures is investigated numerically over time-scales ranging from fast switching processes on a picosecond scale to thermally activated reversal on a microsecond time-scale. A simulation of the stochastic Landau-Lifshitz equation of motion is used as well as a time quantified Monte Carlo method for the simulation of classical spin systems modeling magnetic Co nanoparticles. For field pulses larger than the Stoner-Wohlfarth limit spin precession effects govern the reversal behavior of the particle while for lower fields a magnetization reversal is only possible when it is assisted by thermal fluctuations.
