Microwave relaxation properties of substituted lithium ferrite

Abstract

The effect of Co, Mn, Ti, and Al substitutions on two important microwave relaxation parameters, the spin-wave linewidth ΔH k and the high field effective linewidth ΔH eff , for lithium ferrite, Li 0.5 Fe 2.5 O 4 , has been examined. Cobalt tends to increase both linewidths, while Mn tends to decrease them. The quantitative dependences, however, indicate that an optimum Mn level, at about 0.5 at./F.U., serves to maximize the ratio ΔH k /ΔH eff . There is no marked change in the effect of cobalt on either linewidth parameter as Ti and/or Al substitutions are made to reduce the saturation induction. However, Ti substitutions are found to substantially decrease ΔH k , while causing a moderate (factor of two) increase in ΔH eff .