Vacancy-induced ferromagnetism of MoS₂ nanosheets

Outstanding magnetic properties are highly desired for two-dimensional ultrathin semiconductor nanosheets. Here, we propose a phase incorporation strategy to induce robust room-temperature ferromagnetism in a nonmagnetic MoS₂ semiconductor. A two-step hydrothermal method was used to intentionally introduce sulfur vacancies in a 2H-MoS₂ ultrathin nanosheet host, which prompts the transformation of the surrounding 2H-MoS₂ local lattice into a trigonal (1T-MoS₂) phase. 25% 1T-MoS₂ phase incorporation in 2H-MoS₂ nanosheets can enhance the electron carrier concentration by an order, introduce a Mo⁴⁺ 4d energy state within the bandgap, and create a robust intrinsic ferromagnetic response of 0.25 μ_B/Mo by the exchange interactions between sulfur vacancy and the Mo⁴⁺ 4d bandgap state at room temperature. This design opens up new possibility for effective manipulation of exchange interactions in two-dimensional nanostructures.