Uniform sense condition magnetic field sensor using differential magnetoresistance

摘要

A ferromagnetic thin-film based sensing arrangement having a plurality of magnetic field sensors on a substrate each having an intermediate layer of a nonmagnetic material with two major surfaces on opposite sides thereof with one of a pair of magnetically permeable films each of a magnetoresistive, anisotropic ferromagnetic material correspondingly positioned thereon with first and second oriented sensors therein respectively having a selected and a reversing magnetization orientation structure provided with one of said pair of permeable films thereof for orienting its magnetization in a selected direction absent an externally applied magnetic field in at least partly opposing directions. Alternatively, these magnetizations of the films can be oriented in the same direction but with the other film member of the pair provided adjacent a coupling layer that antiferromagnetically couples thereto a further ferromagnetic layer on an opposite side thereof of a lesser thickness for one sensor and a greater thickness for the other. Such a sensing arrangement can be formed by providing a succession of material layers on a substrate with one or more coupling layers for antiferromagnetically coupling ferromagnetic layers on opposite sides thereof including a permeable film. Selective removal of the succession follows to provide unequal numbers of coupling layers for the two kinds of sensors or unequal thicknesses of corresponding ferromagnetic layers corresponding to the coupling layer and the providing of a pinning layer for both kinds of sensors which are thereafter separated by further material removal.