Validation of the transition state theory with Langevin-dynamics simulations

Finite-element Langevin-dynamics simulations are performed in order to extract the attempt frequency of small magnetic particles as a function of an applied perpendicular field. The obtained values of the attempt frequency are in excellent agreement with the analytical results of [Kalmykov, J. Appl. Phys. 96, 1138 (2004)]. It is shown that an external field that is applied perpendicularly to the easy axis with a strength of just about 1% of the anisotropy field is strong enough that the framework of the transition state theory (TST) for broken symmetries can be applied. It is concluded that for most realistic structures, the attempt frequency can be numerically calculated by broken symmetry-TST formulism. (C) 2010 American Institute of Physics. [doi:10.1063/1.3460639]