Perpendicularly oriented polycrystalline BaFe11.1Sc0.9O19 hexaferrite with narrow FMR linewidths

We demonstrate low ferromagnetic resonance (FMR) linewidths and high remanence magnetization in polycrystalline M-type Sc-doped Ba ferrites having anisotropy fields of similar to 8 kOe and perpendicular orientation of the spontaneous magnetization vector. This is a result of applying a unique processing technique that makes use of a polymer network-assisted alignment of hexaferrite particles in high magnetic fields. The resulting compacts exhibit high squareness (M-r/M-s similar to 92%) and low FMR linewidths (similar to 530 Oe) at X-band and Ka-band. This represents an similar to 74% decrease in linewidth compared with previous reports for polycrystalline BaM ferrites using conventional processes. We also have detailed origins of the FMR linewidth broadenings in terms of some important theoretical models. These materials have potential for use in low frequency self-biased microwave/millimeter devices such as circulators and isolators.