Title: Fluctuations and Noise Signatures of Driven Magnetic Skyrmions,
Abstract: Magnetic skyrmions are particle-like objects with topologically-protected
stability which can be set into motion with an applied current. Using a
particle-based model we simulate current-driven magnetic skyrmions interacting
with random quenched disorder and examine the skyrmion velocity fluctuations
parallel and perpendicular to the direction of motion as a function of
increasing drive. We show that the Magnus force contribution to skyrmion
dynamics combined with the random pinning produces an isotropic effective
shaking temperature. As a result, the skyrmions form a moving crystal at large
drives instead of the moving smectic state observed in systems with a
negligible Magnus force where the effective shaking temperature is anisotropic.
We demonstrate that spectral analysis of the velocity noise fluctuations can be
used to identify dynamical phase transitions and to extract information about
the different dynamic phases, and show how the velocity noise fluctuations are
correlated with changes in the skyrmion Hall angle, transport features, and
skyrmion lattice structure.