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We study current-perpendicular-to-plane (CPP) geometrical giant magnetoresistance (GMR) and magnetic switching property for single spin-valves (SVs). Applying a synthetic antiferromagnet (SyAF) instead of a single ferromagnet film as a free layer, the resistance-change area product ΔRA of the SVs is strongly enhanced from ∼ 1.84 mΩ μm² to ∼ 16.8 mΩ μm² and the CPP-GMR ratio changes from 0.8% to 3.6%. The study of the magnetic switching behavior by both experiment and single-domain thermal activation modeling shows that the SVs with SyAF as a free layer approaches a single-domain magnet even with a low aspect ratio 1 as long as its size diminishes to ∼0.18 μm². Because of the single-domain structure, the SVs with SyAF give a size-independent magnetic switching field when the aspect ratio is 1. [ABSTRACT FROM AUTHOR]

A magnetic sensor which consists of a compound magnetic wire and search coil has a novel performance to induce the detection voltage independent of changing rate of AC external field frequency in every one cycle. The detection voltage is changed by the previous magnetized state of the compound magnetic wire. This paper reports the effect of a DC bias magnetic field which is applied with an AC magnetic field to make an asymmetric field. To make a compound wire a previous magnetized state, the demagnetized wire is magnetized by various orienting DC field H/sub 0/. When a symmetric AC field Hex and DC bias field Hb are applied to the wire, the wire is magnetized by an asymmetric magnetic field, which consists of a reset field Hr=Hex+Hb and a set field Hs=Hex-Hb. According to the relationship among the critical field Hp, H/sub 0/ and Hb, Hp is independent of the previous magnetized state of wire at Hb of 25 Oe or larger, and the pulse voltage is always induced at a fixed Hp. This phenomenon is very stable and reproducible. [ABSTRACT FROM PUBLISHER]