Co-Fe/Cu多層膜を用いたCPP-GMR素子におけるMR特性のセンス電流依存性(磁気記録)

概要

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The dependence of the MR properties of CPP (Current Perpendicular to the Plane)-GMR (Giant Magneto-Resistive) sensors with a Co-Fe/Cu multilayer on sensing current was investigated. A CPP-GMR sensor with a [Co_<90>Fe_<10>(1.5 nm)/Cu(2.0 nm)]_<16> multilayer had an MR ratio of 17.5 %. The MR ratio monotonically decreased with increasing sensing current. Split peaks for the MR ratio were also observed in an MR curve, when sensing current was so high as to drastically decrease the MR ratio. We calculated the MR curves with a simple coherent rotation model assuming a circular current induced field, and confirmed that the calculated MR curves were qualitatively in good agreement with experimental ones. The micromagnetic simulation for read-head dimensions also revealed degradation in the MR ratio due to the current induced field. The simulated results indicated that reducing the sensor size would effectively suppress the current induced field, which resulted in high output. The estimated output and head-amp SNR for a size of 50 x 50 nm were over 2 mV and 33 dB, respectively. Therefore, a CPP-GMR sensor with a Co-Fe/Cu multilayer possibly had sufficiently high potential to be a candidate for future recording technology.
2008-05-01