The dynamics of the magnetic moment within the particle is a combination of precession and damping, which can be described by the Landau–Lifshitz–Gilbert (LLG) equation. The effect of thermal fluctuations can be characterized by adding a random field to the usual LLG equation. It is known as the stochastic LLG equation, and it basically enables one to accurately simulate the dynamics of the magnetic moments, accounting for the effect of thermal fluctuations. In the present study, we addressed a suspension composed of magnetic particles with uniaxial magnetic anisotropy, and analyzed the behavior of magnetic moments by solving the Stochastic LLG equation. The viscos motion of particles was simulated by means of Brownian dynamics method. We required a large amount of CPU time to obtain situation results. This is due to the restriction that the time interval in simulations must be significantly smaller than the characteristic time of the precession of the magnetic moment. These considerations exemplify that a new simulation method is indispensable to simulate both the viscous motion of magnetic particles and the motion of magnetic moments inside the particles simultaneously.
Kashiwagi et al. (Wed,) studied this question.