Permanent-magnet-free stabilization and sensitivity tailoring of magnetoresistive field sensors

We have exploited the coupling across a ruthenium spacer between a ferromagnetic and an antiferromagnetic layer to stabilize the magnetization in a given direction and tailor the magnetic sensitivity of the sensor for various applications. Ruthenium is used as the nonmagnetic coupling layer and is self-aligned with the ferromagnetic free layer and antiferromagnetic pinning layer, and the thickness is varied to change the slope of the transfer curve in the linear region, i.e., sensitivity. This simple technique is shown to increase the dynamic range of anisotropic magnetoresistive sensors without additional lithography.