  The presence of magnetic noise in magnetoresistive-based magnetic sensors
degrades their detection limit at low frequencies. In this paper, different
ways of stabilizing the magnetic sensing layer to suppress magnetic noise are
investigated by applying a pinning field, either by an external field,
internally in the stack or by shape anisotropy. We show that these three
methods are equivalent, could be combined and that there is a competition
between noise suppression and sensitivity reduction, which results in an
optimum total pinning field, for which the detection limit of the sensor is
improved up to a factor of ten.
