Metal-to-insulator transition in two-dimensional ferromagnetic monolayer induced by substrate

Two-dimensional(2D) ferromagnetic(FM) materials have great potential for applications in next-generation spintronic devices. Since most 2D FM materials come from van der Waals crystals, stabilizing them on a certain substrate without killing the ferromagnetism is still a challenge. Through systematic first-principles calculations, we proposed a new family of 2D FM materials which combines TaX(X = S, Se or Te) monolayer and Al_2O_3(0001) substrate. The TaX monolayers provide magnetic states and the Al_2O_3(0001) substrate stabilizes the former. Interestingly, the Al_2O_3(0001)substrate leads to a metal-to-insulator transition in the Ta X monolayers and induces a band gap up to 303 meV. Our study paves the way to explore promising 2D FM materials for practical applications in spintronics devices.