Ferromagnetism emerged from non-ferromagnetic atomic crystals.

The recently emerged ferromagnetic two-dimensional (2D) materials provide unique platforms for compact spintronic devices down to the atomic-thin regime; however, the prospect is hindered by the limited number  of ferromagnetic 2D materials discovered with limited choices of magnetic properties. If 2D antiferromagnetism could be converted to 2D ferromagnetism, the range of 2D magnets and their potential applications would be significantly broadened. Here, we discovered emergent ferromagnetism by interfacing non-magnetic WS 2 layers with the antiferromagnetic FePS 3 . The WS 2 exhibits an order of magnitude enhanced Zeeman effect with a saturated interfacial exchange field ~38 Tesla. Given the pristine FePS 3 is an intralayer antiferromagnet, the prominent interfacial exchange field suggests the formation of ferromagnetic FePS 3 at interface. Furthermore, the enhanced Zeeman effect in WS 2 is found to exhibit a strong WS 2 -thickness dependence, highlighting the layer-tailorable interfacial exchange coupling in WS 2 -FePS 3 heterostructures, which is potentially attributed to the thickness-dependent interfacial hybridization.