A vector magnetometer based on a single spin-orbit torque anomalous Hall device

TL;DR

This paper introduces a novel single-device vector magnetometer based on spin-orbit torque, capable of measuring all three components of a magnetic field simultaneously with high spatial resolution and low cost.

Contribution

It presents a new vector magnetometry method using harmonic Hall resistances in a superparamagnetic FM/HM bilayer, enabling three-dimensional magnetic field measurement with a single device.

Findings

Successfully measured 3D magnetic field vectors in experiments.

Demonstrated accurate angular position sensing and magnetic field mapping.

Results agree well with theoretical simulations.

Abstract

In many applications, the ability to measure the vector information of a magnetic field with high spatial resolution and low cost is essential, but it is still 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 superparamagnetic ferromagnet (FM)/heavy metal (HM) bilayer. Under an ac driving current, the first and 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 a L-shaped Hall device with two orthogonal arms, we can measure all the three field components simultaneously, so as to detect both the amplitude and direction of magnetic field in a three-dimensional space. As proof 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.