| Abstrakt: |
A stochastic differential equation that describes the dynamics of single-domain magnetic particles at any temperature is derived using a classical formalism. The deterministic terms recover existing theory and the stochastic process takes the form of a mean-reverting random walk. In the ferromagnetic state diffusion is predominantly angular and the relevant diffusion coefficient increases linearly with temperature before saturating at the Curie point (Tc). Diffusion in the macrospin magnitude, while vanishingly small at room temperature, increases sharply as the system approaches Tc. Beyond Tc, in the paramagnetic state, diffusion becomes isotropic and independent of temperature. The stochastic macrospin model agrees well with atomistic simulations. [ABSTRACT FROM AUTHOR] |
