The stability of magnetic skyrmions against thermal fluctuations and external perturbations is
investigated within the framework of harmonic transition state theory for magnetic degrees of
freedom. The influence of confined geometry and atomic scale non-magnetic defects on the
skyrmion lifetime is estimated. It is shown that a skyrmion on a track has lower activation
energy for annihilation and higher energy for nucleation if the size of the skyrmion is
comparable with the width of the track. Two mechanisms of skyrmion annihilation are …