Reduction of the free layer thickness in GMR devices is desirable in order
to meet higher signal requirements, besides improving the GMR ratio
itself. However, thinning of the free layer reduces the GMR ratio and
leads to poor thermal stability. This problem has been overcome by making
AP2 from an inverse GMR material and by changing the free layer from a
single uniform layer to a ferromagnetic layer AFM (antiferromagnetically)
coupled to a layer of inverse GMR material. Examples of alloys that may
be used for the inverse GMR materials include FeCr, NiFeCr, NiCr, CoCr,
CoFeCr, and CoFeV. Additionally, the ruthenium layer normally used to
effect antiferromagnetic coupling can be replaced by a layer of chromium.
A process to manufacture the structure is also described.