Enhanced Soft Magnetic Properties in N-Doped Amorphous FeCo Thin Film

FeCoNx thin films with various nitrogen fractions are investigated in the quest of low lossy, soft magnetic thin films (SMFs) for high-frequency inductor core. 100 nm thick FeCoNx films were deposited in N-2 + Ar environment (5 m torr) with increasing N-2 volume percent, x% = N-2/(Ar + N-2), up to 30%. While FeCo thin film is isotropic, the incorporation of nitrogen in the film exhibits a well-defined uniaxial magnetic anisotropy (UMA) as a result of reduced stress in the FeCoNx films. FeCoN17.5 thin film with UMA shows superior all-round soft magnetic properties (saturation flux density similar to 1.7 T, coercivity similar to 7.8 Oe, real permeability similar to 381.7 and resistivity similar to 201 mu Omega center dot cm). The study of the dynamic magnetic properties of FeCoNx (x = 15%, 17.5%, and 19%) films reveal two ferromagnetic resonance (FMR) peaks. Double resonance peaks in films with a high concentration of nitrogen might be related to FeCo and Fe-N multiphase in the films. Furthermore, the evolution of the real (mu') and imaginary ( mu'') part of the permeability spectra in the presence of dc magnetic bias field is also examined.