NUCLEATION FIELD FOR 3-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.