Current-perpendicular-to-the-plane (CPP) magnetoresistive (MR) sensor having an antiparallel free (APF) structure with improved magnetic stability

摘要

A current-perpendicular-to-the-plane magnetoresistive sensor has an antiparallel free (APF) structure and soft side shields wherein the upper free layer (FL2) of the APF structure is magnetically coupled antiparallel to the top shield and a top shield seed layer via a nonmagnetic antiparallel coupling (APC) layer. In one embodiment the antiparallel coupling is through an antiferromagnetic-coupling (AFC) layer that provides a dominant antiferromagnetic indirect exchange coupling of FL2 to the top shield. In another embodiment the antiparallel coupling is by an APC layer that decouples FL2 and the top shield and causes the edge-induced magnetostatic coupling between FL2 and the seed layer to dominate. The degree of coupling is controlled by the composition and thickness of the nonmagnetic APC layer between FL2 and the seed layer, and by the thickness of the seed layer.