Medium dynamic field range linear bipolar spin valve sensor through soft pinning the sensing layer

Magnetic sensor with spin valve-GMR technology with medium dynamic range is designed for a diversity of applications, including linear and rotary position measurements, proximity switches, and current sensors. For this, the sensing layer (SL) of the spin valve stack was modified by a soft pinning layer (SPL) through an exchange bias field created by an antiferromagnetic layer which has a lower blocking temperature than the one that is kept adjacent to the pinned layer. Numerical simulation was carried out to control the bias field by keeping a non-magnetic Ru spacer layer between the SPL and SL layers and the results were experimentally verified. The magnetic sensor was fabricated with an operating field range of the order ± 100 Oe having a sensitivity of the order of 0.1 mV/V/Oe near zero field. The thermal performance confirms that the device can be operated in the temperature range of - 40 °C to 125 °C and it has a thermal coefficient of voltage around 15 µV/V/°C.