Ferromagnetic Resonance and Microwave Behavior of ASn-Substituted (A${=}$Ni-Co-Zn) BaM-Hexaferrites

ASn-substituted BaM-hexaferrites with compositions BaFe_12-2x AxSn_xO₁₉, where A = Co, Ni, Zn, and x=0.5--2, were synthesized using a solid-state reaction at 1100-1300 degC. Hexaferrites formation was controlled by X-ray powder diffraction. The static magnetic properties were determined and the ferromagnetic resonance frequency of the powders was obtained using a vector network analyzer and a coplanar waveguide. It is shown that the degree of substitution (x) has a strong influence both on the static magnetic and the microwave behavior of the ceramics. Due to the changes in the anisotropy and saturation magnetization, the ferromagnetic resonance frequency shows a considerable decrease, from the 48 GHz for pure BaFe₁₂O₁₉, to about 10-20 GHz for samples with xap0.5,1