Complex Permeability of Polycrystalline Hexagonal Ferrites

Polycrystalline hexagonal ferrites (Y, Z and W-phases) were prepared by the usual ceramic sintering. Their complex permeability spectra were natural resonance type, and numerically separated into spin rotational and domain wall motion components. For the spin rotational component, it was found that the Snoek's product values of them were far beyond the product values of spinel ferrite. It enabled us to design the thin electromagnetic wave absorbers in the quasimicrowave region. Index Terms--Electromagnetic wave absorber, hexagonal ferrite, permeability, Snoek's product.