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 speed under in plane magnetic field, which provides a useful scheme to measure the DMI strengths. However, recent findings of additional asymmetries such as chiral damping have disenabled unambiguous DMI determination and the underlying mechanism of overall asymmetries becomes under debate. By extracting the DMI-induced symmetric contribution, here we experimentally investigated the nature of the additional asymmetry. The results revealed that the additional asymmetry has a truly antisymmetric nature with the typical behavior governed by the DW chirality. In addition, the antisymmetric contribution changes the DW speed more than 100 times, which cannot be solely explained by the chiral damping scenario. By calibrating such antisymmetric contributions, experimental inaccuracies can be largely removed, enabling again the DMI measurement scheme.
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