Order-disorder effects in the anisotropy of substituted lithium ferrite

In pure lithium ferrite, octahedral (B) site cation ordering is known to affect the first-order anisotropy constant K1. Investigations of Co- and Mn-Co-substituted Li ferrite have now revealed changes in K1concurrent with ordering which are much larger than those occurring in pure Li ferrite. The spinwave linewidth ΔHkalso exhibits large changes. These effects have not been reported to date. The large changes with disorder are found to arise from migration of Co to the tetrahedral (A) sites. Low level Mn substitutions are found to modify Co behavior. Manganese-induced oxidation of Co²⁺to Co³⁺is shown to be a plausible mechanism.