Single Domain Spin Orbit Torque Enabled Magnetic Field Sensor with Offset Compensation

Reducing the zero-field offset is crucial for absolute field measurements. In this work we present a device that can be used to measure magnetic fields smaller than 1 mT and compensate the respective offsets. The device employs a modulated spin-orbit-torque (SOT) to reduce the offset. The sensor is sensitive to in-plane fields parallel to the current direction Ixx. Depending on whether a positive or negative current is applied, the damping like spin-orbit torque results in a positive or negative Mz component of the single domain state, respectively. This out of plane Mz component depends on the Bx field and it is measured via the anomalous Hall effect. The signal is obtained by subtracting the measured Mz components of the two opposing current directions. It is shown that bias fields applied orthogonal to the sensitive direction does not increase the offset but changed the sensitivity of the sensor.