  We show that thermal stability of magnetic skyrmions can be strongly affected
by entropic effects. The lifetimes of isolated skyrmions in atomic Pd/Fe
bilayers on Ir(111) and on Rh(111) are calculated in the framework of harmonic
transition state theory based on an atomistic spin model parametrized from
density functional theory. Depending on the system the attempt frequency for
skyrmion collapse can change by up to nine orders of magnitude with the
strength of the applied magnetic field. We demonstrate that this effect is due
to a drastic change of entropy with skyrmion radius which opens a novel route
towards stabilizing sub-10 nm skyrmions at room temperature.
