Emergence of Magnetic Skyrmions in Ferromagnetic Transition Metal Chalcogenides*

Van der Waals magnets have drawn great attention since the discovery of intrinsic 2D ferromagnetism. Due to the extraordinary correlations among charge, spin, orbital and lattice degrees of freedom, layered magnetic transition metal chalcogenides (TMCs) is a rich area for uncovering exotic topological phenomena. Particularly, magnetic skyrmions have high potential for ultra-dense memory and logic devices while skyrmions are yet to be experimentally found in TMC monolayers (MLs) despite theoretical predictions. Here we report the realization of quasi-2D TMC Cr₂Te₃ down to 1 ML on SrTiO₃ (111) by molecular beam epitaxy (MBE). The spin-glass behavior in thick films has enabled the investigation of magnetic skyrmions in the ML limit, while robust ferromagnetism survives in insulating ML film (T_c =17 K). Topological Hall effect and unusual hysteresis observed in transport/magnetometry measurements unveil the emergence of stable magnetic skyrmions, down to 1 ML. The unique concomitant occurrence of 2D ferromagnetism and skyrmionic behavior in ultrathin Cr₂Te₃ films widens TMC-based material possibilities for various quantum hybrid studies.