Patent ID: 7345854

Claim:
A GMR sensor of the spin-valve type including a reference layer having a magnetic moment that is free to move under the influence of external fields, comprising: a substrate; an undercoated lower shield formed on the substrate; a lower dielectric gap layer formed on the lower shield; an antiferromagnetic pinning layer formed on the lower dielectric gap layer; a five layer structure formed on said pinning layer, said five layer structure further comprising: a pinned ferromagnetic layer, magnetically pinned by said antiferromagnetic pinning layer; a first spacer layer formed on said pinned layer; an intermediate ferromagnetic layer formed on said first spacer layer and strongly exchange coupled by an exchange coupling field across said first spacer layer to said pinned layer to form a synthetic ferrimagnetic configuration; a second spacer layer formed as a composite trilayer of Ru/Cr/Cu on said intermediate layer; a ferromagnetic reference layer formed on said second spacer layer and completing said five layer structure, said reference layer being weakly exchange coupled by an exchange coupling field across said second spacer layer to form a synthetic ferrimagnetic configuration, and the magnetic moment of said reference layer being free to move; a third spacer layer formed on said reference layer; a ferromagnetic free layer formed on said third spacer layer, said free layer having a magnetic moment that is free to move; and, wherein the angle between the magnetic moments of said reference layer and said free layer is set initially between approximately 95° and 125° when there is no external magnetic field and wherein the magnetic moments of said reference layer and said free layer thereby move in opposite directions when there is an external magnetic field; a capping layer formed on the free layer; an upper gap layer formed on the capping layer; an upper shield formed on the upper gap layer.