Chirality-induced antisymmetry in magnetic domain wall speed

Dae-Yun Kim,Soong-Geun Je,Hyeok-Cheol Choi,Yune-Seok Nam,Sug-Bong Choe,Duck-Ho Kim,Joo-Sung Kim,Byoung-Chul Min,Yong-Keun Park,Min-Ho Park

doi:10.1038/am.2017.216

Abstract

In chiral magnetic materials, numerous intriguing phenomena such as built-in chiral magnetic domain walls (DWs) and skyrmions are generated by the Dzyaloshinskii–Moriya interaction (DMI). The DMI also results in asymmetric DW speeds under an in-plane magnetic field, which provides a useful scheme to measure the strength of the DMI. However, recent findings of additional asymmetries such as chiral damping have inhibited the unambiguous determination of the DMI strength, and the underlying mechanism of overall asymmetries comes under debate. Here, we experimentally investigate the nature of the additional asymmetry by extracting the DMI-induced symmetric contribution from the DW speed. Our results reveal that the additional asymmetry has a truly antisymmetric nature with the typical behavior governed by the DW chirality. In addition, the antisymmetric contribution alters the DW speed by a factor of 100, dominating the overall variation in DW speed. Thus, experimental inaccuracies can be largely removed by calibration with such antisymmetric contributions, enabling the standard DMI measurement scheme.

Highlights

Understanding magnetic domain wall (DW) motion is of extreme importance owing to its potential application in spintronic devices such as memory and logic devices.[1,2,3,4] In order to improve the performance of these devices, it is crucial to achieve fast domain walls (DWs) speeds
It is worthwhile to note that the antisymmetric contribution exhibits similar behavior to that of the εST measurement (Figure 2a), with three regimes composed of a transition regime (BW-NW regime) inbetween two saturation regimes (NW ± regimes)
As the DW chirality governs such typical regimes, one can conclude that the antisymmetric nature of A can be mainly attributed to the DW chirality

Summary

Introduction

Understanding magnetic domain wall (DW) motion is of extreme importance owing to its potential application in spintronic devices such as memory and logic devices.[1,2,3,4] In order to improve the performance of these devices, it is crucial to achieve fast DW speeds. Many other groups have subsequently reported the existence of an additional asymmetry, which makes it difficult to unambiguously determine the symmetric axis. In this regard, the investigation of the additional asymmetry is important from an academic viewpoint, and to ensure an error-free DMI measurement technique. By extracting the well-known DMI-induced symmetric contribution from the DW’s motion, the additional asymmetry is found to exhibit a truly antisymmetric nature, which is governed by the DW’s chirality

Methods

Results

Conclusion