Microwave permeability and absorbing properties of nano-meter Fe46Co44B10 thin films

FeCoB thin films can have high resistivity and relatively high saturation magnetization which are desired for microwave frequency application such as wireless inductors and absorbers. In this study, Fe₄₆Co₄₄B₁₀ films in thickness of nanometer were deposited on glass substrates by magnetron sputtering method under a uniform applied magnetic field. The as-deposited films exhibit low coercivity of a few Oe, anisotropy field of 50 Oe and 4 pi Ms of 16.5 kG. Such properties in these films result in a ferromagnetic resonance frequency as high as 2 GHz, a relative permeability mu\´ of 350 and a low dissipation mu" of 50 in the frequency range of 0.05-1 GHz. A resonant absorbing peak locates around 2 GHz which is important to be used as absorbers.