Thermal stability of skyrmions

Magnetic skyrmions are vortex-like magnetic textures with a topologically nontrivial spin structure making a continuous transformation from the skyrmion to the uniform state impossible. Hence skyrmions are regarded as topologically protected attracting large interest concerning applications in data storage, neuromorphic computing, and digital logic. For such kind of applications an extraordinary stability of the skyrmion state against thermal fluctuations is required. In real matter, due to its discrete nature, topological protection translates into the existence of an energy barrier between the skyrmion and the uniform state leading to a finite skyrmion lifetime. Therefore the experimental determination of the skyrmion lifetime becomes important. Within this work we focus on experimental studies of the skyrmion lifetime in a variety of magnetic systems ranging from monolayers to bulk samples. We discuss previous experimental studies on the thermal stability of magnetic skyrmions in systems based on Fe/Ir(111) and in B20-materials. New experimental results on skyrmion nucleation and decay are obtained for thin Ni/Fe-films on Cu(001) using threshold photoemission magnetic circular dichroism in combination with photoemission electron microscopy (TP-MCD-PEEM). The results are interpreted using an Arrhenius-like activation behavior and evaluated regarding energy barriers and pre-exponential factors of the skyrmion dynamics.