Macro-Spin Modeling of Spin Orbit Torque Biased Wheatstone Bridge for Tunneling Magnetoresistive Sensors

Tunneling magnetoresistive (MR) sensors are valued for their compact size, high sensitivity, and wide bandwidth, yet typically require additional fabrication processes to achieve linear output characteristics. In this simulation study, we demonstrate through simulation that a spin orbit torque (SOT)-biased Wheatstone bridge structure can electrically bias the magnetizations of adjacent sensing elements into opposite directions, thereby realizing built-in linearization of the sensor response. Utilizing macro-spin model based on the Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation, we systematically analyzed the performance of a magnetic tunnel junction-based bridge sensor under various operating conditions. The free-layer magnetization is shown to be predominantly biased by the field-like SOT generated from the input current. The device’s optimal operating point is identified as the intersection between the bias current dependences of sensitivity and working range, enabling dynamic tuning of sensor characteristics through current modulation. Furthermore, both material and geometric parameters, particularly the spin torque efficiencies and aspect ratio, offer additional design flexibility. These results establish practical guidelines for engineering current-tunable, SOT biased MR sensors, and highlight their potential for adaptive magnetic sensing systems.