High-temperature ferromagnetic resonance (FMR) in FePt-based media materials is studied for the first time. The FMR linewidth (ΔH) as a function of temperature (T), field angle (θH), and the volume fraction (x) of carbon in the material is determined, and the effective Gilbert damping constant and the Bloch-Bloembergen relaxation time are estimated. The data suggest that at temperatures 10-45 K below the Curie temperature, two-magnon scattering and spin-flip magnon-electron scattering make comparable contributions to ΔH. With a decrease in T, ΔH increases due to enhancement of the two-magnon scattering. ΔH can be tuned via varying x and shows a maximum at θH≈45 when varying θH.
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