Vector Magnetometer Based on a Single Spin-Orbit-Torque Anomalous-Hall Device

In many applications, the ability to measure the vector information of a magnetic field with high spatial resolution and low cost is essential, but remains a challenge for existing magnetometers composed of multiple sensors. Here, we report a single-device based vector magnetometer, which is enabled by spin-orbit torque, capable of measuring a vector magnetic field using the harmonic Hall resistances of a ferromagnet (FM)/heavy metal (HM) bilayer with superparamagnetic behavior. Under an ac driving current, the firstand second-harmonic Hall resistances of the FM/HM bilayer show a linear relationship with the vertical and longitudinal component (along the current direction) of the magnetic field, respectively. By employing an L-shaped Hall device with two orthogonal arms, we can measure all the three field components simultaneously, thereby detecting both the amplitude and direction of magnetic field in a three-dimensional space. As proofs of concepts, we demonstrate both angular position sensing on the three coordinate planes and vector mapping of magnetic field generated by a permanent magnet, both of which are in good agreement with the simulation results. Crosstalk between vertical and longitudinal field components at large field is discussed using theoretical models.

Automated summary

In this study, we report a single-device based vector magnetometer enabled by spin-orbit torque, capable of measuring a vector magnetic field with high spatial resolution and low cost. By utilizing the harmonic Hall resistances of a ferromagnet/heavy metal bilayer with superparamagnetic behavior, this magnetometer can measure the vector information of a magnetic field. A L-shaped Hall device is employed to simultaneously measure all three field components, enabling the three-dimensional measurement of magnetic field amplitude and direction.