  The magnetization switching dynamics of biaxial single-domain homogeneous
ferromagnetic particles, in which the two easy axes are perpendicular to each
other, is simulated using a 4-state clock model. A zero-field mapping of the
statics between the symmetric 4-state clock model and two decoupled Ising
models is extended to non-zero field statics and to the dynamics. This
significantly simplifies the analysis of the simulation results. We measure the
magnetization switching time of the model and analyze the results using droplet
theory. The switching dynamics in the asymmetric model is more complicated. If
the easy axis is perpendicular to the stable magnetization direction, the
system can switch its magnetization via two different channels, one very fast
and the other very slow. A maximum value for the switching field as a function
of system size is obtained. The asymmetry affects the switching fields
differently, depending on whether the switching involves one single droplet or
many droplets of spins in the stable magnetization configuration. The angular
dependence of the switching field in symmetric and asymmetric models is also
studied.
