Oriented barium hexaferrite thick films with narrow ferromagnetic resonance linewidth

Hexagonal BaFe12O19 ferrite films, having thicknesses ranging from 200-500 mu m, were prepared by a screen printing process followed by sintering heat treatments. Structural, magnetic, and microwave measurements confirmed that the polycrystalline films were suitable for applications in self-biasing microwave devices in that they exhibited a large remanence (4 pi M-r=3800 G), high hysteresis loop squareness (M-r/M-s=0.96) and low microwave loss. A derivative linewidth Delta H of 310 Oe was measured at 55.6 GHz. This represents the lowest Delta H measured in polycrystalline hexaferrite materials. Delta H can be further improved by reducing porosity and improving the c-axis orientation of grains in polycrystalline ferrite. (c) 2006 American Institute of Physics.