The relaxation time of the magnetization of uniaxial single-domain ferromagnetic particles in the presence of a uniform magnetic field

The relaxation time of the magnetization of uniaxial single-domain ferromagnetic particles is evaluated for magnetic field applied to an arbitrary angle to the easy axis in the entire dissipation range, i.e., for very low damping (VLD), intermediate-to-high damping (IHD), and crossover values. The calculations are based on the Mel'nikov-Meshkov method [J. Chem. Phys. 85, 1018 (1986)] for bridging the VLD and IHD Kramers escape rates for mechanical particles (the Kramers turnover problem) as extended by Coffey [Adv. Chem. Phys. 117, 483 (2001); Phys. Rev. E 63, 021102 (2001)] to the analogous magnetic spin problem. It is shown that the analytical results are in complete agreement with the relaxation time calculated numerically from the solution of the stochastic Landau-Lifshitz-Gilbert equation. (C) 2004 American Institute of Physics.