Although it is known that exchange bias can be utilized in abutted
junctions for longitudinal stabilization, a relatively large moment is
needed to pin down the sensor edges effectively. Due to the inverse
dependence of the exchange bias on the magnetic layer thickness, a large
exchange bias has been difficult to achieve by the prior art. This
problem has been solved by introducing a structure in which the magnetic
moment of the bias layer has been approximately doubled by pinning it
from both above and below through exchange with antiferromagnetic layers.
Additionally, since the antiferromagnetic layer is in direct abutted
contact with the free layer, it acts directly to help stabilize the
sensor edge, which is an advantage over the traditional magnetostatic
pinning that had been used.