Novel topological spin textures for low-energy spintronics

TOPOSPIN-prosjektet utforsket nye muligheter for mindre og energieffektiv informasjonsteknologi. For dette formålet studerte vi fysikken til spesielle defekter på nanonivå ? kjent som topologiske defekter ? som naturlig oppstår i materialer med kiral magnetisk struktur. I den første fasen av prosjektet undersøkte og klassifiserte vi forskjellige typene en- og todimensjonale spinnstrukturer som oppstår i kirale magneter. Etterpå viste vi hvordan disse spinnteksturene reagerer på ytre stimuli, inkludert elektriske og magnetiske felt, og vi lærte hvordan vi kan kontrollere dem ved å endre formen av materialet. Bortsett fra viktig innsikt i de grunnleggende fysiske egenskapene til kirale magneter, tilrettela TOPOSPIN for et betydelig sprang fremover når det gjelder fremtidige applikasjoner. Prosjektet introduserte konseptuelt nye måter for å oppdage funksjonelle nanoskopiske spinnteksturer som kan brukes i fremtidens informasjonsteknologi. Med dette hadde TOPOSPIN betydelig innvirkning på fremgangen på feltet og utviklingen av fremtidens spintronikk-teknologi som reflektert av flere publikasjoner i tidsskrifter med høy impaktfaktor og en nylig patentsøknad innlevert av TOPOSPIN-teamet.

TOPOSPIN led to several publications in high-impact journals, including Nat. Phys., ACS Nano and Nano Lett., reflecting the importance for the community and new trends that we triggered. In particular, our publication in Nat. Phys. was already downloaded >6400 times and stimulated international follow-up projects. A patent application has been filed for circular racetrack memory, showing the successful technology transfer of the research results. Because of the technological relevance of the research and acquired skills, the PhD and postdoc who worked on TOPOSPIN evolved into highly attractive scientists and transitioned into jobs in industry right after their contracts ended. In summary, TOPOSPIN led to an important leap ahead; different international groups picked up the research and will drive the progress in the years to come. To keep the momentum and ensure that this promising line of research can be continued also in Norway, additional funding is highly desirable.

The goal of this proposal is to identify and demonstrate novel topological spin structures in chiral magnets that can be manipulated at ultra-low energy and allow device paradigms to be extended into new realms of magnetism. The research is motivated by the recent discovery that nanoscopic, topological spin textures can be controlled via spin-polarized currents, bearing great potential as information carriers in next-generation spintronics devices. Prime examples are domain walls and skyrmions, which represent stable nano-objects that cannot be destroyed by a continuous transformation of the spin system. The exploration of functional topological objects, however, is just beginning and the experimental access at the nanoscale is challenging. Thus, the diversity of emergent spin textures and their physics still fall into largely uncharted territory. In this project we will focus on completely new types of topological spin textures and their functional properties, investigating, e.g., magnetic disclinations and helimagnetic domain walls. We will gain experimental access using state-of-the-art scanning probe and cathode-lens microscopy and develop a comprehensive understanding about the zoo of emergent stable field configurations. These configurations will be classified with respect to their topology, creating fundamental knowledge about the formation process, physical properties, and interactions. By electrical currents and magnetic fields we will control the position and movement of individual spin textures and explain the dynamical nanoscale response. Innovative topology-based opportunities for their technological usage will be demonstrated by designing and operating device-like test architectures. The work bases on our pioneering, preliminary research in the field and the outcome will clarify the future role of topological spin textures as functional nano-objects for spintronics, data-storage, information processing and other potential device paradigms.