CPP-GMR of spin valves with Co _xFe _1-x alloy

Spin valves with free and pinned layers constructed from Co ₅₀Fe ₅₀ exhibit higher current-perpendicular-to-plane (CPP) giant-magnetoresistance (GMR) than the conventional Co ₉₀Fe ₁₀ alloy. In order to investigate this enhancement mechanism, we measured CPP-GMR and the crystalline structure of spin valves with Co ₉₀Fe ₁₀, Co ₇₀Fe ₃₀, Co ₅₀Fe _l50 and Co ₂₀Fe ₈₀ for pinned and free layers. The spin valves with Co ₅₀Fe ₅₀ and Co ₂₀Fe ₈₀ show the same CPP-GMR and these are higher than those with Co ₉₀Fe ₁₀ and Co ₇₀Fe ₃₀. These results do not agree with the report about the Fe-Ni and Co-Ni systems that calculated that concludes that the stoichiometric concentration has the highest CPP-GMR. In the Co-Fe system, the crystalline structure and the strain also contribute to CPP-GMR.