Nanoscale magnetic skyrmions in metallic films and multilayers: a new twist for spintronics

Abstract

Magnetic skyrmions are chiral quasiparticles that show promise for the transportation and storage of information. On a fundamental level, skyrmions are model systems for topologically protected spin textures and can be considered as the counterpart of topologically protected electronic states, emphasizing the role of topology in the classification of complex states of condensed matter. Recent impressive demonstrations of the control of individual nanometre-scale skyrmions — including their creation, detection, manipulation and deletion — have raised expectations for their use in future spintronic devices, including magnetic memories and logic gates. From a materials perspective, it is remarkable that skyrmions can be stabilized in ultrathin transition metal films, such as iron — one of the most abundant elements on earth — if in contact with materials that exhibit high spin–orbit coupling. At present, research in this field is focused on the development of transition-metal-based magnetic multilayer structures that support skyrmionic states at room temperature and allow for the precise control of skyrmions by spin-polarized currents and external fields. Magnetic skyrmions are quasiparticles that hold promise for future spintronic devices. In this Review, the detection, creation, manipulation and deletion of individual skyrmions in ultrathin films and in multilayers are surveyed, and their control by currents and external fields is discussed.