Skyrmion lattice rotation dynamics in Cu₂OSeO₃

We use small-angle neutron scattering (SANS) to investigate the skyrmion lattice (SkL) in Cu₂OSeO₃ under a radial thermal gradient. By applying heat to the center of a disk-shaped sample in a Corbino geometry, we are able to induce a continuous rotation of the SkL. The rotation speed varies as a function of both applied field and temperature within the A phase, and can be resolved in real time by recording movies of the SANS diffraction patterns. In many cases the SkL rotates in a coherent fashion throughout the entire sample, either as a single domain or as sychronized subdomains. The rotation velocity is not uniform, and the SkL frequently remains locked at specific orientations for extended periods before continuing the rotation. This behavior is most likley due to the competition between the restoring torque, due to the crystaline anisotropy, the torque exerted by the heat flow, and the collective SkL dynamics. Given the large data sets, the SANS data analysis is automated using Artificial Intelligence and a gradient descent algorithm, which takes advantage of the six-fold symmetry