Electrodeposition of highly functional thin films for magnetic recording devices of the next century

A review is presented of the recent progress in research and development of soft magnetic films for magnetic recording heads of the future primarily on the basis of the work performed by the author's research group. Films of CoNiFe ternary alloy with high saturation magnetic flux density B_S and low coercivity, H_C were successfully produced by electrodeposition. A typical film, designed as `HB-CoNiFe', had the composition of Co₆₅Ni₁₂Fe₂₃ (at.%) with B_S = 2.0-2.1 T and H_C<2 Oe. Properties other than B_S and H_C were also investigated; namely, magnetostriction, λ_S, corrosion properties, and film resistivity ρ. The key to the success in obtaining low H_C with high B_S was to form film with very fine crystals. The inclusion of small amount of sulfur was found to be essential for producing such a film with the desired magnetic properties. The film has been applied to the construction of a new type of merged-GMR head, which is considered as a breakthrough for materializing ultra high-density magnetic recording.