Atomistic Simulations of Antiferromagnetic Skyrmions' High-Speed Dynamics and Contrast with Domain Wall Motion

High-velocity dynamics of Antiferromagnetic skyrmions (AFMSks), as well as their ability to display relativistic behavior, have yet to be fully understood. Unlike Domain Walls (DWs), their one-dimensional counterparts, AFMSks should not obey Lorentz invariance, because they have been claimed to be non-commutative solitons. It was also previously shown that AFMSks have a special critical velocity limit v_c, always less than the magnon group speed, as dictated by the Dzyaloshinskii–Moriya interaction (DMI) which also serves to stabilize them in the material. Using VAMPIRE atomistic simulations, we show that AFMSks possess fundamentally different dynamic properties than DWs. We perform a systematic study of the dynamic deformations in skyrmion radius, as well as the width of their bounding domain wall, which we claim are universally related to the AFMSk velocity relative to the critical limit v_c. We present a novel outlook on the role of skyrmion compactness in their deformation patterns, velocity limits, as well as the emergence or absence of behaviors similar to ones observed in relativistic DWs. These results could prove to be significant to the field of solitonics and the potential applications of AFMSks for novel logic and memory devices.