Magnetoresistive sensor with pinned SAL

摘要

A magnetoresistive sensor including a magnetoresistive (MR) sensing element, a nonmagnetic layer ("spacer") contacting the magnetoresistive sensing element; a first antiferromagnetic (AFM) layer contacting the nonmagnetic layer such that the nonmagnetic layer is sandwiched between the magnetoresistive sensing element and the antiferromagnetic layer; a ferromagnetic soft adjacent layer (SAL) contacting the antiferromagnetic layer such that the antiferromagnetic layer is sandwiched between the nonmagnetic layer and the soft adjacent layer; and a second antiferromagnetic layer contacting the SAL such that the SAL is sandwiched between the first and second antiferromagnetic layers. The two antiferromagnetic layers provide a stronger pinning effect. In one embodiment of the invention, the magnetoresistive sensing element is an anisotropic magnetoresistive (AMR) sensing element comprising a soft ferromagnetic layer. In another embodiment of the invention, the magnetoresistive sensing element is giant magnetoresistive (GMR) sensing element comprising a plurality of layers. The bias scheme can be non-symmetric, or may be symmetric around the magnetoresistive sensing element. An exchange biased bilayer (AFM/SAL) can have a multilayered structure such as AFM/SAL/AFM/SAL. . . . In this configuration, the SAL layer can be thin, so that a high exchange field with a high resistance can be obtained.