Rana Saha, Holger L. Meyerheim, Börge Göbel, Binoy Krishna Hazra, Hakan Deniz, Katayoon Mohseni, Victor Antonov, Arthur Ernst, Dmitry Knyazev, Amilcar Bedoya-Pinto, Ingrid Mertig & Stuart S. P. Parkin
Nature Communications (2022) 13:3965
Transition-metal dichalcogenides intercalated with 3d-transition metals within the van der Waals (vdW) gaps have been the focus of intense investigations owing to their fascinating structural and magnetic properties. At certain concentrations the intercalated atoms form ordered superstructures that exhibit ferromagnetic or anti-ferromagnetic ordering. Here we show that the self-intercalated compound Cr1+δTe2 with δ ≈ 0.3 exhibits a new, so far unseen, three-dimensionally ordered (2×2×2) superstructure. Furthermore, high resolution X-ray diffraction reveals that there is an asymmetric occupation of the two inequivalent vdW gaps in the unit cell. The structure thus lacks inversion symmetry, which, thereby, allows for chiral non-collinear magnetic nanostructures. Indeed, Néel-type skyrmions are directly observed using Lorentz transmission electron microscopy. The skyrmions are stable within the accessible temperature range (100–200 K) as well as in zero magnetic field. The diameter of the Néel skyrmions increases with lamella thickness and varies with applied magnetic field, indicating the role of long-range dipole fields. Our studies show that selfintercalation in vdW materials is a novel route to the formation of synthetic non-collinear spin textures.