Engineering of Intrinsic Chiral Torques in Magnetic Thin Films Based on the Dzyaloshinskii-Moriya Interaction

TL;DR

This paper demonstrates how chiral torques induced by the Dzyaloshinskii-Moriya interaction in patterned magnetic thin films can control domain wall motion, with tunable effects and potential for intrinsic magnetic device applications.

Contribution

It introduces a novel magnetic racetrack design that leverages DMI-induced chiral torques to bias domain wall velocity and enables estimation of torque magnitude through velocity asymmetry.

Findings

Chiral torques can bias domain wall velocity in magnetic thin films.

Design modifications allow tuning of chiral magnetic fields up to 7.8 mT.

Intrinsic torques can spontaneously propel domain walls without external forces.

Abstract

The establishment of chiral coupling in thin magnetic films with inhomogeneous anisotropy has led to the development of artificial systems of fundamental and technological interest. The chiral coupling itself is enabled by the Dzyaloshinskii-Moriya interaction (DMI) enforced by the patterned noncollinear magnetization. Here, we create a domain wall track with out-of-plane magnetization coupled on each side to a narrow parallel strip with in-plane magnetization. With this we show that the chiral torques emerging from the DMI at the boundary between the regions of noncollinear magnetization in a single magnetic layer can be used to bias the domain wall velocity. To tune the chiral torques, the design of the magnetic racetracks can be modified by varying the width of the tracks or the width of the transition region between noncollinear magnetizations, reaching effective chiral magnetic fields of up to 7.8 mT. Furthermore, we show how the magnitude of the chiral torques can be estimated by measuring asymmetric domain wall velocities, and demonstrate spontaneous domain wall motion propelled by intrinsic torques even in the absence of any external driving force.