In this section we present a very particular case of switching
process in which it is possible to obtain magnetization reversal
of a whole grain ensemble with external fields whose amplitude is
below the Stoner-Wohlfarth limit. This kind of switching process
has considerable applications in hard-disks realizations for
several reasons that we will see below. Our purpose is to show
that, although the medium is consisted of many weakly (exchange
and magnetostatically coupled) interacting grains, it can be
approximately treated as a collection of non-interacting grains.
Therefore, the necessary conditions for the switching can be
investigated with the uniform mode theory applied to a single
grain.
Subsections
