Novel topological spin textures for low-energy spintronics

The TOPOSPIN project explored novel opportunities towards smaller and energy-efficient information technology. For this purpose, we studied the physics of special nanoscopic imperfections ? known as topological defects ? that naturally arise in materials with chiral magnetic order. In the initial phase of the project, we investigated and classified the different types of one- and two-dimensional spin structures that arise in chiral magnets. Afterwards, we showed how these spin textures react to external stimuli, including electric and magnetic fields, and we learnt how to control them by changing the shape of the host material. Aside from important insight into the fundamental physical properties of chiral magnets, TOPOSPIN facilitated a significant leap ahead concerning future applications. The project introduced conceptually new ways for detecting functional nanoscopic spin textures that can be applied in future memory technology. With this, TOPOSPIN had substantial impact on the progress in the field and the development of next-generation spintronics technology as reflected by several publications in high-impact journals and a recent patent application filed by the TOPOSPIN-team.

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.