Skyrmion Pinball and Topological Sorting

In this work we simulate the dynamic behavior of skyrmions under the influence of a square lattice of obstacles [1,2]. First, we consider a single skyrmion while varying the size and strength of the obstacles. We find that as the obstacle size is changed, several dynamic phases may appear or vanish. For smaller obstacles, the system exhibits fewer dynamic phases because as the obstacle size is reduced. On the other hand, if the obstacle size is too large, the system may also exhibit fewer dynamic phases due to the reduction in the size of the gaps between the obstacles, which confines the skyrmion motion. Thus, the highest number of dynamic phases appears for intermediate obstacle sizes. Motivated by these results, we consider the behavior of skyrmions of different species [3] under the influence of the square obstacle array. Our preliminary results indicate that is possible to separate the species according to their different skyrmion Hall angles when a driving current is applied.

[1] S.-Z. Lin, C. Reichhardt, C. D. Batista, and A. Saxena, Phys. Rev. B 87, 214419 (2013).
[2] A. Rosch, Nat. Nanotechnol. 8, 160 (2013).
[3] C. J. O. Reichhardt and C. Reichhardt, Phys. Rev. E 99, 012606 (2019).