High-frequency permeability of sputtered Fe-Co-B-based soft magnetic thin films

High-frequency characteristics of a series of soft magnetic Fe-Co-B-based thin films are investigated in the range of 0.5-5 GHz. It is found that in-plane anisotropy can be caused by oblique incidence or applying an external field during deposition. The permeability and the resonance frequency are basically consistent with Snoek's law. Ni can improve the magnetic properties greatly except for the decrease of resistivity. In order to reduce the dissipation and increase the resistivity, SiO2 is added to the film. Excellent high-frequency permeability of (Fe40Co40B20)(0.619)Ni-12.642-(SiO2)(25.416) is obtained: the resonance frequency exceeds 2.2 GHz; the real and the imaginary parts of the permeability at 0.5 GHz are 476 and 92, respectively; the resistivity of the film reaches 682 mu Omega cm. High-frequency permeability of FeCoNiB-SiO2 thin film. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim