Edge Magnetism in Colloidal MoS2 Triangular Nanoflakes

The control of localized magnetic domains at the nanoscale holds great promise for next-generationspintronic applications. Colloidal transition metal dichalcogenides nanostructures are experimen-tally accessible and chemically tunable platforms for spintronics, deserving dedicated research toassess their potential. Here, we investigate from first principles free-standing triangular MoS2nanoflakes with sulfur-terminated, hydrogen-passivated edges, to probe intrinsic spin behavior atvarying side lengths. We find a critical edge length of approximately 1.5 nm separating nonmag-netic nanoflakes from larger ones with a magnetic ground state emerging from several, energeticallycompeting spin configurations. In these systems, the magnetic activity is not uniformly distributedalong the edges but localized on specific “magnetic islands” around molybdenum edge atoms. Thelocalization of magnetic moments is robust even in non-equilateral nanoflake geometries, highlight-ing their intrinsic stability regardless of the (high) symmetry of the hosting structure. These findingsestablish that the S-terminated, H-passivated triangular MoS2 nanoflakes are a stable and experi-mentally accessible platform via colloidal synthesis for low-dimensional, next-generation spintronicdevices.