Universality of Dzyaloshinskii-Moriya interaction effect over domain-wall creep and flow regimes

TL;DR

This study demonstrates that the influence of the Dzyaloshinskii-Moriya interaction (DMI) on domain-wall dynamics remains consistent across both creep and flow regimes, highlighting its fundamental role in chiral magnetic phenomena.

Contribution

The paper provides experimental evidence that the DMI effect is invariant over different domain-wall motion regimes, clarifying its universal role in chiral magnetic structures.

Findings

DMI effect remains unchanged from creep to flow regimes

Symmetric contribution of DMI is consistent across regimes

Antisymmetric contribution diminishes across regimes

Abstract

Chirality causes diverse phenomena in nature such as the formation of biological molecules, antimatters, non-collinear spin structures, and magnetic skyrmions. The chirality in magnetic materials is often caused by the noncollinear exchange interaction, called the Dzyaloshinskii-Moriya interaction (DMI). The DMI produces topological spin alignments such as the magnetic skyrmions and chiral domain walls (DWs). In the chiral DWs, the DMI generates an effective magnetic field $H_{DMI}$, resulting in a peculiar DW speed variation in the DW creep regime. However, the role of $H_{DMI}$ over the different DW-dynamics regimes remains elusive, particularly due to recent observation of distinct behaviors between the creep and flow regimes. We hereby demonstrate experimentally that the role of $H_{DMI}$ is invariant over the creep and flow regimes. In the experiments, the pure DMI effect is quantified by decomposing the symmetric and antisymmetric contributions of the DW motion. The results manifest that the antisymmetric contribution vanishes gradually across the creep and flow regimes, revealing that the symmetric contribution from $H_{DMI}$ is unchanged. Though the DW dynamics is governed by distinct mechanisms, the present observation demonstrates the uniqueness of the DMI effect on the DWs over the creep and flow regimes.