Soft magnetic thin film, method for preparing same and magnetic head

Abstract

A soft magnetic thin micro-crystalline film of Fe.sub.a B.sub.b N.sub.c (at %) wherein B is at least one of Zr, Hf, Ti, Nb, Ta, V, Mo and W, and O<b.ltoreq.20 and O<c.ltoreq.22 except the range of b.ltoreq.7.5 and c.ltoreq.5, shows low coercivity Hc of 80-400 Am.sup.-1 (1-5 Oe) which is stable upon heating at elevated temperature for glass bonding. This film is produced by crystallizing an amorphous alloy film of the similar composition of 350.degree.-650.degree. C. to a crystal grain size up to 30 nm to provide uniaxial anisotropy and increased magnetic permeability at higher frequency. It can also provide low magnetostriction around .lambda.s= . Composite magnetic head is made using this thin film. Diffusion preventive SiO.sub.2 layer disposed between ferrite core and this thin film in the magnetic head prevents an interdiffusion layer and suppress beat in the output signal.