FMR SPECTRA OF ORIENTED GAMMA-FE2O3, CO-GAMMA-FE-2, O-3, CRO2, AND MPTAPES

Ferromagnetic resonance spectra have been measured at 34.5 GHz on orie nted gamma-Fe2O3, Co-gamma-Fe2O3, CrO2 and MP tapes. Particle orientat ion distribution functions were determined by measuring the angular de pendence of remanence. The distribution functions were used to calcula te FMR spectra using the Landau-Lifshitz equation and the method of Ne tzelmann. The anisotropy energy, packing fraction and damping constant were adjusted in order to fit the data. The values of the damping con stants obtained from the fits ranged from a low of 0.051 for CrO2 to a high of 0.92 for MP. These values, including previously measured damp ing constants for Ba-ferrite, correlate well with the switching speed measurements of Doyle and co-workers, which show CrO2 to be the slowes t and MP the fastest.