Temperature and frequency dependence of linewidth in BaFe12O19

In order to determine the important magnetic loss mechanisms in the hexagonal ferrite BaFe12O19, the ferromagnetic resonance linewidth has been measured as a function of temperature and frequency. Measurements were performed over the temperature range of 60° to 300°K and frequency range 52 to 64 GHz, both for pure and for Mn-substituted barium ferrite. Our results indicate that the bulk of the linewidth in high-quality, pure barium ferrite crystals can be attributed to an intrinsic Kasuya-LeCraw scattering process. The same measurements on manganese-substituted barium ferrite (BaFe11.8Mn0.2O19) revealed a somewhat more complicated temperature dependence for the linewidth. The magnetic loss for the Mn-substituted sample is explained as the sum of two separate contributions: a Kasuya-LeCraw scattering loss, and a temperature peak process due to crystal impurities.