Atomistic simulations of distortion-limited high-speed dynamics of antiferromagnetic skyrmions

In antiferromagnetic (AFM) materials, localized self-sustaining states called solitons, namely, domain walls (DWs) and skyrmions, can be efﬁciently driven by currents and achieve velocities of several kilometers per second. These solitons are massive particles and therefore cannot travel faster than a limiting velocity akin to the speed of light for the material. The speciﬁcs of these high-velocity dynamics, in which solitons begin to display relativistic effects, have been well understood for the case of DWs (single-dimensional particles). Here, we perform an extensive and systematic atomistic study of both one-dimensional and two-dimensional soliton dynamics in chiral magnetic materials, both at and away from angular momentum compensation. We develop an elastic restorative force model to explain the dynamic skyrmion deformations, supported by simulation data. We claim that these deformations arise from a local imbalance of gyrotropic forces. We also present an outlook on the role of skyrmion compactness in their deformation patterns, velocity limits, as well as the absence of behaviors similar to ones observed in relativistic DWs. We claim that limits on skyrmion compactness also impede their ability to reach the velocity regime where relativistic effects begin to occur in rapidly moving DWs, due to the critical skyrmion breakdown behavior. These results could prove to be signiﬁcant to the ﬁeld of spintronics, as well as the potential applications of skyrmions for novel logic and memory devices. DOI: