Sensor saturation for hysteresis reduction in GMR magnetometers

Giant Magnetoresistance (GMR) sensors offer several advantages over other technologies for the development of general-purpose magnetometers. They are applicable for both AC and DC fields, are relatively sensitive, can be fabricated to measure over a large range of field strengths, have a high-speed response and are low cost. One significant disadvantage of the GMR sensor is that the output is a function of the history of the magnetic fields that have been on the device, i.e., hysteresis. In this work, we demonstrate that hysteresis effects can be virtually eliminated by saturating the GMR sensor prior to making a field measurement. This forces the sensor to follow the same path of output voltage versus applied field for each measurement. Within the limits of our equipment, we cannot determine any hysteresis effects when using this saturation technique and therefore measurement repeatability is dramatically improved.