Interactions Underpinning Novel Skyrmion and Hedgehog Phases in Centrosymmetric Helimagnetic Strontium Iron Oxides

• Applicants: Dr. Dmitri Efremov; Dr. Darren Peets
• Subject Area: Experimental Condensed Matter Physics ; Theoretical Condensed Matter Physics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 455319354

Our recent work on the centrosymmetric helical magnet SrFeO3 revealed skyrmion- and hedgehog-lattice phases, in which the spin orientation forms a lattice of topologically-protected spin vortices, ordered in two or three dimensions. Such phases had never been previously observed in a centrosymmetric material, and the Dzyaloshinskii-Moriya interactions that ordinarily stabilize helical, skyrmion, and hedgehog phases are forbidden by symmetry in centrosymmetric materials. The magnetism in SrFeO3 is thus entirely new, and requires urgent attention and detailed characterization. Inelastic neutron scattering is particularly important for an understanding, since it directly accesses the magnetic excitation spectrum, allowing us to extract the interaction parameters governing the magnetism. Extracting these parameters requires theoretical modelling, however, which is currently impossible. The physics in this material are so new that even the foundation required to construct the required model does not yet exist. This project aims to capitalize on the knowledge, expertise, and samples already present in Dresden to collect the data required to understand the interaction parameters in SrFeO3, while simultaneously constructing the theoretical foundation required to analyze it. We are uniquely positioned to make significant advances in understanding unique skyrmion and hedgehog lattice phases, and lay the groundwork for finding more such phases in other centrosymmetric materials.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Dmytro Inosov