Microwave absorption in single-domain particles involving first- and second-order uniaxial magnetic anisotropy constant

Abstract

The ferromagnetic resonance absorption is calculated for powder assemblies of non-interacting magnetically uniaxial particles involving the anisotropy constants K 1 and K 2. It is shown that both constants can be obtained by FMR separately within a relative error of the second-order anisotropy constant rm|Δ K 2| = |0.01 K 1|. This determination method is applied on Co 2+/Ti 4+- and Zn 2+/Ti 4+-substituted barium ferrite with an amount of substitution of 0 ≤ x ≤ 1.25. For both substituted barium ferrite powders it is found that K 2 is less than the 1% of K 1. Consequently the decrease of the anisotropy field strength with substitution must be effected by the decrease of K 1 alone.