In current synthetically pinned CPP SV designs, AP2 always makes a negative contribution
to the device's GMR since its magnetization direction must be anti-parallel to
the pinned layer (AP1). This effect has been reduced by replacing the conventional
single layer AP2, that forms part of the synthetic pinned layer, with a multilayer
structure into which has been inserted at least one layer of a material such as
tantalum that serves to depolarize the spin of electrons that traverse its interfaces.
The result is a reduction of said negative contribution by AP2, leading to a significant
increase in the GMR ratio.
