We succeeded in developing CoFe spin valves with an antiferromagnetic Ir-Mn film. Ir-Mn single-layer films and spin valves of Ta(5 nm)/Ir-Mn(8 or 9 nm)/Co90Fe10(x nm)/Cu(3 nm)/Co90Fe10(3 nm)/NiFe(2 nm)/CoZrNb(10 nm)/ (x=2, 2.3, 2.6 nm), prepared by the sputtering method, showed the crystal structure of a fcc (111) preferred orientation. As-deposited CoFe spin valves with Ir-Mn exhibited an interfacial exchange coupling energy of J=0.192 erg/cm2 (Hua∼640 Oe at tCoFe=2 nm), that was the highest ever reported for as-deposited antiferromagnetic films, such as NiO, NiMn, and FeMn. Furthermore, CoFe spin valves with Ir-Mn exhibited a higher blocking temperature of 260 °C, and a higher MR ratio of 6.37% than the spin valves with FeMn film. After annealing, the MR ratio increased to 7.82%. On the other hand, the Hua decreased about 100 Oe after annealing. The Hua-T curve was, however, improved and the Hua at 100 °C increased to 400 Oe. The decrease in Hua was not observed after second annealing and seems to be stabilized by first annealing.

In this work, we present a suitable material for metal-based spin-valve in current-perpendicular-to-plane (CPP) geometry. The AΔR (A is the element size and ΔR is the change in resistance) was investigated for three kinds of free and pinned layers material, that is, Co90Fe10, Fe50Co50, and Fe50Co50 with half-atomic Cu layers. When the free and pinned layers are 5 nm, AΔR is 1.0 mΩ μm2, 1.6 mΩ μm2, and 2.9 mΩ μm2, respectively. Moreover, the dual-type spin valve having Fe50Co50 with half-atomic Cu layers achieved 5.2 mΩ μm2. According to the free and pinned layers thickness dependence of AΔR, the spin-dependent resistance at the interfaces between ferromagnetic layers and spacer Cu is enhanced mainly by changing from Co90Fe10 to Fe50Co50, and the spin-dependent bulk resistance in free and pinned layers is enlarged by inserting half-atomic Cu layers.

No abstract

No abstract

No abstract