FREQUENCY-DEPENDENCE OF THE FERROMAGNETIC-RESONANCE LINEWIDTH AND EFFECTIVE LINEWIDTH IN MANGANESE SUBSTITUTED SINGLE-CRYSTAL BARIUM FERRITE

Ferromagnetic resonance (FMR) and high field effective (HFE) linewidth measurements have been made at 10-90 GHz for low conductivity Mn subs tituted single crystal barium ferrite, BaFe12-xMnxO19, with x = 0.1. T he manganese compensates excess Fe2+ and reduces conductivity. Measure ments were made on c-plane thin disks magnetized to saturation along t he disk axis. A shorted waveguide technique was used to measure the FM R profiles and linewidths in the 55-90 GHz frequency range. High Q cav ity techniques and an analysis procedure for the FMR high field tail r esponse were used for the HFE linewidth determinations in the 10-60 GH z 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 l inewidths increase linearly with frequency at 0.4 Oe/GHz and have a ze ro frequency extrapolation of 4 Oe. This lower zero frequency extrapol ation for the HFE linewidth supports an inhomogeneity origin for the 2 0 Oe FMR linewidth extrapolation. These data indicate intrinsic linewi dths 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.