Noise Fluctuations and Avalanche Statistics of Skyrmions with Quenched Disorder

Magnetic skyrmions are nanoscopic magnetic textures that enjoy topologically-protected stability and exhibit particle-like behavior. Their novel transport properties have generated extensive basic research and show great potential for using skyrmions as information carriers in future high-density magnetic storage and logic devices. At the particle level, both magnetic skyrmions and superconducting vortices - another kind of topological excitations that also behave as particles - admit a common theoretical description. While in real materials, superconducting vortex dynamics is dissipation-dominated, the so-called Magnus force dominates the dynamics of magnetic skyrmions. Using a particle-based model, we simulate two different systems in the presence of quenched disorder: velocity noise fluctuations of current-driven skyrmions and avalanche statistics of flux-driven skyrmions. We obtain the power spectral density, dynamical phase diagram, as well as the avalanche critical exponents as a function of the Magnus force strength. Our results show that both the noise and avalanche properties of skyrmions depart significantly from the known case of superconducting vortices.