Patent ID: 7242556

Claim:
A current perpendicular to plane (CPP) differential giant magnetoresistive (GMR) sensor, comprising: an in stack bias structure; a first magnetic free layer located on a first side of the in stack bias structure and having a magnetic moment biased in a first direction; a second magnetic free layer located at a second side of said in stack bias structure and having a magnetic moment biased in a second direction antiparallel with the first direction; a first pinned layer structure separated from the first free layer by a first spacer layer, the first pinned layer structure having a first reference layer disposed adjacent to the first spacer layer having a magnetic moment pinned in a third direction perpendicular to the first and second directions; and a second pinned magnetic layer separated from second free layer by a second spacer layer, the second pinned layer structure having a second reference layer formed adjacent to the second spacer layer having a magnetic moment pinned in a fourth direction perpendicular to the first and second directions and antiparallel to the third direction; the in stack bias structure further comprising: a layer of antiferromagnetic material; first, second and third ferromagnetic layers formed at a first side of the antiferromagnetic material layer, the first ferromagnetic layer being exchange coupled with the AFM layer, the second ferromagnetic layer being separated from and antiparallel coupled with the first ferromagnetic layer by a first AP coupling layer, the third magnetic layer being separated from and antiparallel coupled with the second ferromagnetic layer by a second AP coupling layer; fourth and fifth ferromagnetic layers formed at a second side of the antiferromagnetic material layer the fourth ferromagnetic layer being exchange coupled with the AFM layer and the fifth ferromagnetic layer being separated from and antiparallel coupled with the fourth ferromagnetic layer by a third antiparallel coupling layer; a first bias coupling layer separating the first free layer from the third ferromagnetic layer, the first bias coupling layer being of such a thickness as to weakly antiparallel couple the magnetic moments of the first free layer and the third ferromagnetic layer without pinning the magnetic moment of the first free layer; and a second bias coupling layer separating the fifth magnetic layer from the second free layer, the second bias coupling layer being of such a thickness as to weakly antiparallel couple the magnetic moments of the fifth magnetic layer and the second free layer without pinning the magnetic moment of the second free layer.