Current-perpendicular-to-the-plane spin-valve films with iron-added magnetite layers

A current-perpendicular-to-the-plane (CPP)-spin-valve sensor with iron-added magnetite layers (IMLs) was investigated. We prepared bottom synthetic-pin spin-valve films with CoFe ∕ IML ∕ CoFe sandwiched layers as both free layers and pinned layers. The slope of resistance-change-area product ( Δ R A ) versus IML thickness is around 0.5 - 0.6 Ω μ m 2 ∕ nm , and this indicates that using IMLs results in large bulk scattering. Magnetite and iron grains were observed in transmission electron microscopy images even in a 2-nm-thick IML in a CPP giant magnetoresistance structure. As a result, Δ R A up to 2 - 2.5 m Ω μ m 2 and MR ratio of 2.0%-2.6% at RA of 0.08 - 0.1 Ω μ m 2 were obtained by using IML in CPP-spin-valve films.