Trochoidal motion and pair generation in skyrmion and antiskyrmion dynamics under spin-orbit torques

Skyrmions and antiskyrmions in magnetic ultrathin films are characterised by topological charge describing how the spins wind around their core. This governs their response to forces in the rigid core limit. However, internal core excitations are relevant, the dynamics become far richer. We that current-induced spin-orbit torques can lead to phenomena such as motion and skyrmion-antiskyrmion pair generation that only occurs either the skyrmion or antiskyrmion, depending on the symmetry of the Dzyaloshinskii-Moriya interaction. Such dynamics are induced by core, leading to a time-dependent helicity that governs the motion of skyrmion and antiskyrmion core. We compute the dynamical phase diagram a combination of atomistic spin simulations, reduced-variable, and machine learning algorithms. It predicts how spin-orbit torques control the type of motion and the possibility to generate skyrmion by antiskyrmion seeding.