Skyrmion Dynamics at Finite Temperatures: Beyond Thiele's Equation.

Magnetic textures are often treated as quasiparticles following Thiele's equation of motion. We demonstrate via spin model simulations of the current-driven and Brownian motion of ferromagnetic skyrmions that the existing theory based on Thiele's equation is insufficient to describe the dynamics of skyrmions at finite temperatures. We propose an extended equation of motion that goes beyond Thiele's equation by taking into account the coupling of the skyrmion to the magnonic heat bath leading to an additional dissipative term that is linear in temperature. Our results indicate that this so-far-neglected magnon-induced friction dominates for finite temperatures and Gilbert damping values typical for thin films and multilayers.