Skyrmion soliton motion on periodic substrates by atomistic and particle based simulations

We compare the dynamical behavior of magnetic skyrmions interacting with square and triangular defect arrays just above commensuration using both an atomistic model and a particle-based model. Under an applied drive, the initial motion is a kink traveling through the pinned skyrmion lattice. For the square defect array, both models agree well and show a regime in which the soliton motion is locked along 45$^\circ$. The atomistic model also produces locking of a soliton along 30$^\circ$, while the particle-based model does not. For the triangular defect array, the atomistic model exhibits soliton motion locked to 30$^\circ$ over a wide region of external driving force values. In contrast, the particle-based model gives soliton motion locked to 45$^\circ$ over only a small range of external driving force values. The difference arises because the nondeforming particle model facilitates meandering skyrmion orbits while the deformable atomistic model enables stronger skyrmion-skyrmion interactions that reduce the meandering. Our results indicate that soliton motion through pinned skyrmion lattices on a periodic substrate is a robust effect and could open the possibility of using solitons as information carriers. Our results also provide a better understanding of the regimes for which particle-based models of skyrmions are best suited.
Comment: 7 pages, 5 figures