Exchange-Biased Anisotropic Magnetoresistive Field Sensor

IrMn exchange-biased anisotropic magnetoresistive sensors have been optimized for increased outputs and reduced noise. An ~56% increase in peak-to-peak outputs has been achieved in IrMn exchange-biased NiFe thin-film sensors, relative to sensors without IrMn. Critically, these sensors' transfer functions show a linear and symmetric magnetic field response with small hysteresis. The tradeoff between detection range and sensitivity has also been explored, and an inverse proportional relationship is observed. In addition, sensor noise performance can be improved with an IrMn exchange bias layer and further enhanced by the addition of a thin MgO layer between the NiFe and the Ta capping layer. The decrease in magnetic 1/f noise can be attributed to magnetization stabilization by IrMn and a reduction in pinning sites by MgO. This improved performance from IrMn exchange-biased anisotropic magnetoresistive sensors renders them promising for many different applications.