Ferromagnetic resonance linewidths of MnCd ferrites: Effect of eddy-current processes

The ferromagnetic resonance linewidth is measured at 11 GHz from 77 to 300 K for polycrystalline MnxCd0.5Fe2.5-xO4 ferrites with 0.4 less than or equal to x less than or equal to 10.6. The influence of the cooling procedure is also analyzed. Ferromagnetic resonance linewidths are fitted according to the classical contributions of porosity, anisotropy, and eddy-current losses. Linewidths around 400 Oe are found for x = 0.5 in the whole temperature interval. Linewidth broadening due to anisotropy is detected for x > 0.5 at low temperatures. Eddy-current losses take place at high temperatures for x < 0.5. These eddy-current losses are minimized by slow cooling. Activation energies of 0.094 eV are obtained for these conduction processes, in good agreement with previous impedance spectroscopy measurements.