Nucleation Field for Three‐Dimensional Rotation in Inhomogeneous Ferromagnets

Based on the method developed for the one‐dimensional rotation process the nucleation field for three‐dimensional rotation is deduced from the linearized micromagnetic equation for magnetic inhomogeneities due to a spatial variation of the magnetocrystalline anisotropy energy. Comparing the nucleation field of the one‐dimensional rotation with that of three‐dimensional rotation, it turns out that one‐dimensional rotation describes experimental data of sintered magnets much better than the latter one. The physical process of the nucleation is dominated by the low‐dimensional rotation – especially the one‐dimensional rotation – due to the limited freedom of magnetization state by the alignment of the magnetization within grains and the existence of an easy axis in uniaxial magnets.