  The S=1/2, nearest-neighbor, kinetic Ising model has been used to model
magnetization switching in nanoscale ferromagnets. For this model, earlier work
based on the droplet theory of the decay of metastable phases and Monte Carlo
simulations has shown the existence of a size dependent spinodal field which
separates deterministic and stochastic decay regimes. We extend the above work
to study the effects of an oscillating field on the magnetization response of
the kinetic Ising model. We compute the power spectral density of the
time-dependent magnetization for different values of the amplitude and
frequency of the external field, using Monte Carlo simulation data. We also
investigate the amplitude and frequency dependence of the probability
distributions for the hysteresis loop area and the period-averaged
magnetization. The time-dependent response of the system is classified by
analyzing the behavior of these quantities within the framework of the distinct
deterministic and stochastic decay modes mentioned above.
