LAUSR

Abstract SrFe12-2xCoxRuxO19 become magnetically soft with Co and Ru doping. The magnetization is high, but the anistropic field becomes low. The FT-IR spectra suggest that Co and Ru substitute for Fe at the 4f1 site. At this site, the substitution of Co and Ru with low magnetic moments weakens the anisotropy. The sharp magnetic resonances observed in x = 0.3, 0.5 and 0.7 are due to the domain wall movement. The natural magnetic resonance frequency falls in the frequency of 2–18 GHz. The Co and Ru doping increases both the magnetic loss tangent and the dielectric loss tangent. The high magnetic and dielectric loss tangents are in favor of high attenuation factors. With good impedance matching and high attenuation factor, the microwave absorption properties are excellent in x ≥ 0.3. In x = 0.5, the bandwidth is 11.8 GHz centered at 10.5 GHz. In each x > 0.5 sample, the optimum bandwidth is broader than 9 GHz. In x = 1.1, at 1.9 mm, the absorption bandwidth is broader than 9 GHz from 9 GHz to higher than 18 GHz centered at 11.6 GHz. Compared with the advanced materials published in recent decades, the bandwidth of the present work are very competitive.