Magnetic skyrmions, sometimes teasingly called magic knots or mysterious particles, are nanometer-scale whirling cylinders of magnetization (see figure 1). The spatially localized objects are highly mobile and the smallest possible magnetic configurations in nature. They are thus promising for applications in the emerging field of spintronics, which uses the electron spin as an information carrier in addition to or instead of the electron charge. To explore the unconventional and potentially useful features of skyrmions, research to date has focused on novel classes of bulk and recently synthesized nanolayers and multilayers of magnetic metals.1,2
For many years the primary question surrounding skyrmions was whether they even exist. Mathematically, in the majority of physical systems, localized structures similar to skyrmions are unstable and collapse spontaneously into linear singularities. But three decades ago, a surprising mathematical development identified a group of low-symmetry magnetic materials that defy the general rule...