Resonancelike dispersion for W-type barium ferrite composites with c-axis anisotropy

Abstract

Two types of dispersions, namely, resonancelike and relaxationlike dispersions, and their significantly different high-frequency magnetic properties and attenuation characteristics have been studied for barium ferrite composites BaCoxZn2-xFe16O27 with x=0.5-1.3. The composites with x=0.5, 0.6, and 0.65 have c-axis anisotropy and resonancelike dispersion. For the resonancelike dispersion, a high ratio of μ max″/(μ0 ′ -1) can be achieved and, therefore, even if (μ0′ -1) is small, relatively large μmax″ can be still acquired. Due to their high resonance frequency and magnetic loss, the composites can achieve much low reflectivity (RL≤-20 dB) in x to ku bands at small thickness, as compared to composites with c-plane anisotropy. The origin in the two dispersions is attributed to the different types of anisotropy, which lead to much broader resonance-frequency distribution for c-plane anisotropy than for c-axis anisotropy. © 2011 American Institute of Physics.