Motions of magnetic particle with quartic crystalline anisotropy

The theory of the motions of a fine magnetic particle in a viscous Newtonian medium under the influence of a magnetic field is derived along with applicable constraints. The best orienting field of an isolated magnetic particle with quartic crystalline anisotropy is calculated. The results show that the optimum orienting field is not 2 K₁/M_s. The orienting time is critically affected by the quartic crystalline anisotropy. The positive value of K₂ makes the particle orient faster, while the negative value of K₂ makes the particle orient slower