Magnetic skyrmions are swirling nanoscale spin structures that are stable against perturbations and could potentially be used to create novel memory devices. The structures are also of fundamental interest because they have led, for example, to the discovery of intriguing topological phenomena. In skyrmionic memory devices, information could be encoded in the magnetic configuration and transferred by pushing the spin textures along nanostructures by means of spin-polarized currents. Compared with magnetic domain walls, which have also been proposed for magnetic storage applications, skyrmions can be moved by much lower current densities1, suggesting that the devices would have lower power consumption and less critical energy dissipation issues. Moreover, skyrmions can be as small as a few nanometres across and could potentially provide an ultrahigh information-storage density.

On page 899 of this issue, Naoto Nagaosa and Yoshinori Tokura review recent advances in the field2. Skyrmions were first observed only a few years ago, but have now been observed in various magnetic materials, including both bulk and thin-film samples. After a comprehensive account of these observations, Nagaosa and Tokura examine the topological properties and the current-induced dynamics of skyrmions, and discuss the prospects for applications in skyrmionics.

Significant challenges still need to be overcome before skyrmionic devices become a reality3. There are, for example, issues related to material properties: the skyrmion phase has been observed only up to temperatures of 250 K (ref. 4), and in most cases can only be stabilized by an external magnetic field. Furthermore, most reported observations have been of lattices of skyrmions in thin films, but it is likely that skyrmionic devices will require individual skyrmions to be nucleated and controllably propagated in nanostructured thin-films.

Considerable progress has already been made in addressing these issues, particularly in 2013. Computational studies5,6 have examined current-induced skyrmion motion in confined geometries, and the nucleation of skyrmions in nanowires and nanodisks with spin-polarized currents7; individual skyrmions have been nucleated using a spin-polarized current from a scanning tunnelling microscope8; and skyrmion lattices have been observed in MnSi nanowires9. Among other advances, the coming year could perhaps see an experimental demonstration of current-induced nucleation and propagation of individual skyrmions in nanowires.