Effect of Ar-ion Bombardment on Soft Magnetic Properties of Fe and Fe-Hf Films Produced by Dual-type Ion Beam Sputtering((A)Amorphous Alloys)

Soft magnetic properties of Fe metal and Fe-Hf alloy thin films produced by a dual-type ion beam sputtering (DIBS), and the effect of Ar-ion bombardment during sputtering (i.e., the assist effect) on their microstructure and soft magnetic properties have been investigated. It has been found that in the case of Fe films, the bombardment with a low current density results in the nano-crystalline films with small grain sizes and then a small coercivity. The smallest coercivity of the Fe films was obtained 260 A/m when Ar-ion bombardment was modulated, which seems to be caused by the effect of the lamination of colummnar structure consisting of bcc Fe grains with small sizes. On the other hand, in the case of Fe-Hf films with Hf content up to 7 at%, which are known to be characterized with a non-equilibrium bcc phase having 5 to 20 nm fine grains as well as good soft magnetic properties having a high saturation magnetization, the bombardment has no significant effect for the improvement of their soft magnetic properties. The reason may be related to the fact that the grain sizes of Fe-Hf films produced by the assisted sputter-deposition are rather large