Dynamics of thermally activated reversal in nonuniformly magnetized single particles

Abstract

The dynamics of thermally activated reversal in elongated ferromagnetic particles is studied. A micromagnetic model is used which accounts for thermal fluctuations through the addition of a stochastic fluctuation field. Results are given approximating a particle of 5:1 aspect ratio, with exchange length equal to particle radius, which is typical of current particulate media. Fast relaxation of the magnetization is observed. Thermal effective volumes inferred from our results can be significantly less than particle volumes.