Dual-Spin-Valve Elements Using PtMn Films

Abstract

PtMn-dual-spin-valve and PtMn-single-spin-valve unshielded elements using NiFe/Cu/NiFe films with longitudinal hard bias were tested by measuring the transfer curves in various transverse magnetic fields. Transfer curves measured at ±2kOe had steep slopes, showing the rotation of the magnetization direction in the free layer from parallel to antiparallel relation to the pinned layer in low magnetic fields. After magnetization of the CoPt hard-magnetic-bias films in a longitudinal direction, the transfer curve measured at ±200 Oe showed no hysteresis and no Barkhausen-jump. The output of the dual-spin- valve elements increased in proportion to the increase in the sense current, and did not depend on the polarity of the sense current. Further, the asymmetry of the output at ±40 Oe was found to be flat over a wide range of sense currents from -10 mA to +10 m A. The output normalized by the sense current density of the dual-spin-valve element was approximately 1.4 times as large as that of the single-spin-valve element. We have thus demonstrated some advantages of dual-spin-valve elements using antiferromagnetic PtMn films.