Fig. 1: Skyrmion lattice domain growth in oscillating fields.

a Skyrmion positions colored by the lattice orientation α directly after nucleation. The orientation α (illustrated as gray line in color-bar label) is determined by the neighbor positions and is 6-fold symmetric. b After 60 s in an oscillating magnetic field (180 µT peak-to-peak at 100 Hz), the lattice domains have grown significantly. The insets show the corresponding Kerr microscopy image with greyscale representing the OOP-component m_z of the magnetization. c Influence of the field oscillation amplitude on local order parameter ψ₆, orientational correlation length ξ₆, skyrmion diffusion coefficient D and number of skyrmions N. Data points and error bars denote average and standard deviation, respectively, of 10 s window (160 snapshots between 50 and 60 s after nucleation), averaged for three independent measurements each. As a trade-off of effectively reduced pinning and increased random diffusion, ψ₆ and ξ₆ (as measures of the order and lattice domain size, respectively) peak around A = 180 µT. Generally, increased oscillation amplitudes enhance the diffusion D and reduce the number of skyrmions N.