Abstract
We fabricated bottom spin valves (SV) films using Mn–17 mol%Ir–2 mol%Pt antiferromagnetic material. A bottom SV composing of Ta/Ni–20 mol%Fe seed layer shows an improved exchange field (Hex). The high Hex of about 17.4 kA/m was obtained in Si(100)/Ta 3 nm/NiFe 3 nm/Mn–17 mol%Ir–2 mol%Pt 7 nm/Co–10 mol%Fe 1 nm/NiFe 5 nm/Ta exchange biasing layer. The giant magnetoresistance (GMR) and the thermal stability of bottom SVs were evaluated by comparing with a top SV. Bottom SV showed the higher GMR ratio of about 5.2% than a top SV with same thick ferromagnetic layer. It seems that a large short circuit effect of conductance in a free layer of a bottom spin valve. In order to improve thermal stability of a bottom SV, we inserted the synthetic antiferromagnetically coupled pinned layers (Co–Fe/Ru/Co–Fe) between the Mn–17 mol%Ir–2 mol%Pt and Cu layers. Thus, the enhanced thermal stability of Hex can be obtained in bottom synthetic SVs.
