Magnetic Properties of Fe-Si-Al Sputtered Films

Fe-Si (0 - 16 wt% Si) and Fe-Si-Al (3 - 14 wt% Si, 0 8 wt% Al, bal Fe) alloy films were prepared by the DC sputtering technique. In Fe-Si films, the equilibrium phase expected from the phase diagram was obtained under sputtering conditions of PAr = 40 mTorr and VDC = 3.5 kV, while the disordered ¿-phase was realized as a non-equilibrium phase up to about 16 wt% Si under the different sputtering conditions PAr = 40 mTorr and VDC = 2.0 kV. The concentration dependence of the magnetostriction ¿ for Fe-Si films sputtered at VDC = 3.5 kV was found to be nearly the same as that of bulk crystals. However, for Fe-Si films consisting of the ¿-phase, the sign of ¿ remains positive up to about 16 wt% Si. Concentration corresponding to zero magnetostriction, ¿ = 0, determined for Fe-Si-Al films was found to be different from that of bulk crystals, and also different from that of the evaporated films reported by Kadono et al. Comparing the concentration dependence of ¿ with that of magnetocrystalline anisotropy constant K1 , determined by the present authors, it is proposed that films with soft magnetic properties, such as those of Sendust alloy, can best be realized in the Fe-rich concentration portion.