Spin Valve Sensor With Integrated On-Chip Longitudinal Permanent Magnet Biasing for Linear Sensing Applications

This study focuses on fabricating spin-valve giant magnetoresistance (SV-GMR) sensors integrated with longitudinal permanent magnet (PM) biasing, resulting in a linearized field response with reduced hysteresis. For this, CoCrPt thick films were sputter-deposited under optimized conditions to achieve the highest $H_{c}$ value of the order of 1600 Oe with a higher squareness ratio. Detailed finite element modeling (FEM) confirmed that the biasing field less than 40 Oe can be produced by PM with a thickness of $1~\mu $ m across the sensing elements with a gap of $90~\mu $ m. The SV-GMR sensors are patterned into resistors of on-chip push-pull Wheatstone bridge assembly and biased with PM to reduce coercivity with improved linearity. Furthermore, the device’s performance was evaluated across a broader temperature spectrum, revealing notable thermal stability within −40 °C to 125 °C. These findings highlight the sensor’s reliability and precision linear field sensing applications, specifically for low current measurements.