Large anisotropic magnetoresistance in ternary NiFeX films for magnetoresistive heads (abstract)

Abstract

Highly sensitive magnetoresistive heads are required for magnetic disk drives with large areal density. Films with large anisotropic magnetoresistance are among the promising candidates for this purpose. In this work, the effect of third elements, X (Au, Pt, Ag, Cu, Pd, Co, Ru, ZrO2), to Ni80Fe20 alloy on anisotropic magnetoresistivity (Δρ) and other magnetic properties is examined with varying third element composition. Ternary films were deposited by rf sputtering on Ta seed layers. The thicknesses of ternary films were 5–20 nm which were determined by the x-ray reflectivity method. The value of Δρ for ternary films increases when Au, Pt, Ag, Co, and ZrO2 are added. On the other hand, Δρ decreases when Ru is added. Considering the application for the magnetoresistive (MR) head, low ρ0, low Hk, and low Bs are required except for large Δρ. The value of Δρ for Ni74Fe19Au7 film with the thickness of 10 nm is 0.65 μΩ cm which is 20% larger than that for Ni80Fe20. The values of Hk, λ, and Bs for Ni74Fe19Au7 are 4.8 Oe, 1×10−7, and 0.92 T, respectively. Therefore, NiFeAu ternary films are suitable for the MR head. Relative output for the Ni74Fe19Au7 head, calculated by an equation using the above results, is 23% larger than that for the Ni80Fe20 head. Furthermore, the higher output was confirmed by evaluation of fabricated heads.