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

Abstract

Chirality causes diverse phenomena in nature such as the formation of biological molecules, antimatters, noncollinear 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 mu H-0(DMI), resulting in a peculiar DW speed variation in the DW creep regime. However, the role of mu H-0(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 mu H-0(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 DWmotion. The results manifest that the antisymmetric contribution from chiral effect vanishes gradually across the creep and flow regimes, revealing that the symmetric contribution from mu H-0(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, suggesting that the DMI-induced magnetic field is indeed a fundamental quantity of given magnetic systems.