Thermal stability of magnetic states in submicron magnetic islands

The lifetime of magnetic states in single domain micromagnetic islands is calculated within the harmonic approximation to transition state theory. Stable magnetic states, minimum energy paths between them and first order saddle points determining the activation energy are analyzed and visualized on two-dimensional energy surfaces. An analytical expression is derived for the pre-exponential factor in the Arrhenius rate expression for the reversal of the magnetic moment when the external field is directed either along the anisotropy axis or perpendicular to it.