Ferromagnetic Resonance in the Single Crystals of some Ferrites. I

The ferromagnetic resonance absorptions in the single crystals of Mn-Zn ferrite were studied at the wavelength of 3.22 cm and Co-Zn ferrite at 3.22 and 1.27 cm at the temperatures from -195℃ to the Curie-point and the resonance phenomena in the polycrystalline specimens having the same composition were also studied. The magnetic transition through which the first-order magnetocrystalline anisotropy constant K_1 changes its sign were found respectively, at ca. -100℃ and +70℃ for both ferrites and near these temperature two resonance peaks appeared on the resonance curves of polycrystalline specimens. The half line widths were found to depend on the crystallographic directions ; its temperature dependence was also observed. g-factors and K_1 of Co-Zn ferrite were observed as functions of temperature. For Co-Zn ferrite, the temperature dependence of the line width showed a complicated behaviour at first by a rough measurement, but it was found to be monotonous by a further precise investigation. g-value and the order of K_1 of Mn-Zn single crystal at the room temperature agreed with the results of Galt and co-workers, but the large descrepancies between our results and those of Galts\u27 are found in the sign of K_1 and the value of the half line width at the room temperature, i. e., K_1 has a positive sign in our result, but negative in Galts\u27, and the value of the half line widths by us is several times as large as that reported by Galt ; the latter seems to be attributed to the "size effect"