Tuning Magnetism of Monolayer Tungsten Disulfide by Transition Metal Doping*

The recent discoveries of intrinsic ferromagnetism (FM) in two-dimensional (2D) materials have drawn particular attention on encoding the spin behavior at low dimensions. Theoretical investigations of 2D transition metal dichalcogenides (TMDs) have predicted promising perspectives for inducing intrinsic FM in 2D TMD semiconductors by transition metal doping. This has motivated us to experimentally exploit magnetic functionality in monolayer Fe- and V-doped WS₂ - a semiconducting TMD with outstanding optoelectronic and valleytronic properties. Pristine and Fe/V-doped monolayer tungsten disulfide films were grown on SiO₂ substrates by a single-step solution-based method. We observe that while monolayer WS₂ possesses a weak ferromagnetic ordering on its diamagnetic background, Fe:WS₂ and V:WS₂ monolayers exhibit strong, intrinsic FM at room temperature, which is also tunable by controlling dopant concentration. This, coupled with high-resolution TEM images, has suggested the mechanism of strong ferromagnetism in the films, resulting from the magnetic dopants and spatial-dependent ferromagnetic ordering between them. Our findings offer a prospect of developing novel 2D dilute magnetic semiconductors for future spintronic applications.