Frequency dependence of the ferromagnetic resonance linewidth and effective linewidth in maganese substituted single crystal barium ferrite

Abstract

Ferromagnetic resonance (FMR) and high field effective (HFE) linewidth measurements have been made at 10–90 GHz for low conductivity Mn substituted single crystal barium ferrite, BaFe12−xMnxO19, with x=0.1. The manganese compensates excess Fe2+ and reduces conductivity. Measurements were made on c-plane thin disks magnetized to saturation along the disk axis. A shorted waveguide technique was used to measure the FMR profiles and linewidths in the 55–90 GHz frequency range. High Q cavity techniques and an analysis procedure for the FMR high field tail response were used for the HFE linewidth determinations in the 10–60 GHz frequency range. The FMR linewidths increase linearly with frequency at 0.3 Oe/GHz and have a zero frequency intercept of 20 Oe. The HFE linewidths increase linearly with frequency at 0.4 Oe/GHz and have a zero frequency extrapolation of 4 Oe. This lower zero frequency extrapolation for the HFE linewidth supports an inhomogeneity origin for the 20 Oe FMR linewidth extrapolation. These data indicate intrinsic linewidths for barium ferrite of 0.3–0.4 Oe/GHz, a factor of 6–8 larger than intrinsic linewidths in single crystal yttrium iron garnet.