Abstract
Finite-temperature micromagnetics simulations are employed to study the magnetization-
switching dynamics driven by a field applied at an angle to the long axis of an iron nanopillar. A
bi-modal distribution in the switching times is observed, and evidence for two competing modes
of magnetization-switching dynamics is presented. For the conditions studied here, temperature
T = 20 K and the reversal field 3160 Oe at an angle of 75
?
to the long axis, approximately 70%
of the switches involve unstable decay (no free-energy barrier) and 30% involve metastable de-
cay (a free-energy barrier is crossed). The latter are indistinguishable from switches which are
constrained to start at a metastable free-energy minimum. Competition between unstable and
metastable decay could greatly complicate applications involving magnetization switches near the
coercive field.