Theory of current-driven motion of Skyrmions and spirals in helical magnets

TL;DR

This paper provides a theoretical analysis of how Skyrmions and spiral structures in helical magnets respond to external currents, revealing lower critical currents for Skyrmion motion and dynamic scattering signatures.

Contribution

It introduces a numerical study of Skyrmion and spiral dynamics under current, highlighting the reduced pinning and distinctive scattering behavior of Skyrmions.

Findings

Lower critical current density for Skyrmion motion compared to spirals

No intrinsic pinning effect for Skyrmions due to internal deformation

Strong time-dependent Bragg intensity of Skyrmion crystal

Abstract

We study theoretically the dynamics of the spin textures, i.e., Skyrmion crystal (SkX) and spiral structure (SS), in two-dimensional helical magnets under external current. By numerically solving the Landau-Lifshitz-Gilbert equation, it is found that (i) the critical current density of the motion is much lower for SkX compared with SS in agreement with the recent experiment, (ii) there is no intrinsic pinning effect for SkX and the deformation of the internal structure of Skyrmion reduces the pinning effect dramatically, (iii) the Bragg intensity of SkX shows strong time-dependence as can be observed by neutron scattering experiment.