Abstract
Effect of Fe3+ substitution and grain size on magnetic properties in GHz range of M-type hexaferrites BaFe12-x(Ti0.5Mn0.5)xO19 (0≤x≤5) was investigated. Measured complex permeability spectra were well fitted by a model consisting of two types of magnetic susceptibilities corresponding to gyromagnetic spin rotation and domain wall motion. The model fitting shows μ′ in the GHz range is increased when a contribution of the gyromagnetic spin rotation is enhanced. Furthermore, from grain size distribution, it is shown that magnetic loss in the GHz range could be reduced when the average grain size increases and coefficient of variation (CV) decreases. This indicates contribution of a domain wall motion to the magnetic loss is reduced because the domain wall resonance peak shifts to lower frequency and becomes narrower. In our study, it is demonstrated that enhancement of μ′ with low magnetic loss is possible in the GHz region between two resonance peaks of a lower domain wall peak and a higher gyromagnetic spin rotation peak in M-type hexaferrites.
