Magnetic angular position sensor enabled by spin-orbit torque

TL;DR

This paper introduces a magnetic angular position sensor utilizing spin-orbit torque effects in heavy metal/ferromagnet heterostructures, achieving full 360-degree detection with high accuracy and simple design.

Contribution

The work presents a novel, straightforward scheme for magnetic angle sensing using differential Hall voltages, enabling precise 360-degree detection with minimal error.

Findings

Achieved full 360-degree angular detection with high accuracy.

Demonstrated linear angle measurement with an average error below 0.65 degrees.

Validated the sensor's effectiveness in magnetic fields ranging from 500 to 2000 Oe.

Abstract

We propose a simple scheme for magnetic angular position sensor based on current-induced spin-orbit torque effect. A full range detection of 360o is realized with a pair of Hall crosses made of heavy metal/ferromagnet heterostructures. The current axes of the two Hall crosses are aligned orthogonal to each other such that when both devices are subject to a rotational in-plane magnetic field, the differential Hall voltage due to current pulses of opposite polarity exhibits a sine and cosine angular dependence on the field direction, respectively. The field rotational angle is then calculated from the sine and cosine output signals via the arctan2 function. A linear correspondence between the calculated and actual field angle is obtained in the field range of 500-2000 Oe, with an average angle error of 0.38-0.65o.