Layer-modulated magnetism in a two-dimensional transition metal dichalcogenide

While intrinsic magnets rarely occur in nature, long range magnetism in nonmagnetic materials can be introduced in a variety of forms, e.g., adatom intercalation, proximity coupling and defect engineering. The latter has been predicted for several two-dimensional (2D) materials including transition metal dichalcogenides (TMDCs), but such magnetic ordering of spins in the atomically thin limit has not been experimentally realized yet. Here, we will present defect-induced magnetism for an environmentally stable 2D TMDC crystal. By utilizing magneto-transport and polar refractive magnetic circular dichroism techniques, we demonstrate ferromagnetic or anti-ferromagnetic ground state orderings depending on the number of layers, similarly to recently discovered CrI3. Attempts on further manipulation of magnetism within a layer by precise defect engineering will be also shown. Our findings broaden the horizon of 2D magnets to include normally nonmagnetic stable materials by introducing defects.