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 th an or equal to x less than or equal to 10.6. The influence of the cool ing procedure is also analyzed. Ferromagnetic resonance linewidths are fitted according to the classical contributions of porosity, anisotro py, and eddy-current losses. Linewidths around 400 Oe are found for x = 0.5 in the whole temperature interval. Linewidth broadening due to a nisotropy is detected for x > 0.5 at low temperatures. Eddy-current lo sses take place at high temperatures for x < 0.5. These eddy-current l osses are minimized by slow cooling. Activation energies of 0.094 eV a re obtained for these conduction processes, in good agreement with pre vious impedance spectroscopy measurements.