Reversal time of the magnetization of antiferromagnetic nanoparticles

Abstract

The reversal time of the magnetization $\ensuremath{\tau}$ of antiferromagnetic nanoparticles is evaluated for a uniform magnetic field applied at an arbitrary angle $\ensuremath{\psi}$ to the easy axis by using the adaptation of the Kramers escape rate theory to fine ferromagnetic particles given by Coffey et al. [Adv. Chem. Phys. 117, 483 (2001); Phys. Rev. E 63, 021102 (2001)]. The resulting analytic formula yields an accurate approximation to the reversal time $\ensuremath{\tau}$ for all values of the damping and agrees favorably with the numerically exact solution of the corresponding Fokker-Planck equation for the evolution of the probability density function of magnetization orientations.