Magnetic properties of sputtered Co-Ni-Fe-Pd films for thin-film heads

Magnetic properties of Co-Ni-Fe-M (M=Rh, Ir, Pd, Pt) films prepared by sputtering are investigated. It is found that addition of Pd decreases the magnetostriction constant of the films from 1×10^-5 to around zero. On the other hand, addition of other elements, such as Rh, Ir, and Pt, increases it. However, coercive forces of Co-Ni-Fe-Pd films become more than 10 Oe when the magnetostriction is less than 2×10^-6. Multilayered films are investigated to obtain films with low coercive force. 43Co-27Ni-15Fe-15Pd films of 0.17 μm and Al₂O₃ films of 0.01 μm in thickness are layered time-sequentially. This multilayered film has saturation induction of 1.4 T, ≈0 magnetostriction, and a low coercive force of 1.5 Oe. Furthermore, Co-Ni-Fe-Pd films are ascertained to be as resistant to corrosion as Permalloy films. Recording heads with multilayered Co-Ni-Fe-Pd films with Al₂O₃ interlayers as magnetic cores have been fabricated. Recording characteristics were evaluated. These laminated Co-Ni-Fe-Pd/Al₂O₃ heads exhibit about 6 dB better overwrite than Permalloy heads