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.