Microwave relaxation properties of substituted lithium ferrite

The effect of Co, Mn, Ti, and Al substitutions on two important microwave relaxation parameters, the spin-wave linewidth ΔHkand the high field effective linewidth ΔHeff, for lithium ferrite, Li0.5Fe2.5O4, 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 ΔHk/ΔHeff. 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 ΔHk, while causing a moderate (factor of two) increase in ΔHeff.