Theoretical analysis and experimental research on the approach-saturation curve of polycrystalline hexagonal planar ferrites

In order to study the approach-saturation curve and determine the magnetic parameters of polycrystalline hexagonal planar ferrites, we have done a series of theoretical and experimental studies. The approach-saturation expression is σ=σ_s(1-aH^-1-bH^-2-cH^-3 )+χ₁H. We have derived the expressions for b and c of the hexagonal materials: b=(4/15)(K₁/M₂)² , c=(16/105)(K₁/M_s)³. The five coefficients can be determined simultaneously by a computational method in a suitable H-region. For a Co₂Z sample, σ_s=49.37 emu/g, K₁=-1.78×10⁶ erg/cm³; for a Co _1.78Zn_0.22Z sample, σ_s=50.15 emu/g, K₁=-1.72×10⁶ erg/cm³. The experimental results show that a=0, which means that the magnetocrystalline anisotropy field in the hexagonal polycrystalline ferrites is much larger than the magnetoinhomogeneity field, and thus the latter can be be neglected