Ferromagnetic Behaviors In Monolayer MoS₂ Introduced By Nitrogen-doping

Transition-metal dichalcogenides?TMDCs?have been established as the emerging family in the field of two-dimensional?2D?layered materials research due to their unique physical properties and applications in electronics,optoelectronics,and photovoltaics.Defect-free 2D TMDCs are non-magnetic since they shows no magnetic elements and unsaturated bonds,which limits its high potential applications in spintronics and valleytronics.At the same time,imperfections such as edges,dislocations,and grain boundaries in TMDCs may induce magnetism,but the cost is their high crystallinity and unique electronic characteristics.Recently,the discovery of 2D magnetic layered materials has aroused great interest.However,most of them are prepared by mechanical exfoliating from the single crystal bulk,which are small in area,hard to control in thickness,a magnetic transition temperature?Tc?below room temperature and instability in the ambient conditions.At the present stage,these exfoliated magnetic nanomaterials are recognized as a system for studying fundamental science rather than practical applications.Therefore,tremendous efforts are still being made in the functionalization of magnetic properties of 2D TMDCs materials for realizing the manipulation of electron charge and electron spin simultaneously.The manifestation of the ferromagnetic behavior in TMDC has been accomplished through various methods:proton irradiation or annealing under the hydrogen ambient atmosphere,substitution of transition metal or magnetic elements,magnetic proximity effect,and the 2H-1T phase transition.While magnetism associated with these methods offers a lot of opportunities,it is also faces some challenges such as the deterioration of crystallinity,changes in semiconductor natures,and uncontrolled preparation of large-scale ultra-thin layers.Hence,it is of grand significance to develop a batch production method of TMDCs with magnetic response.In this work,theoretical calculations elucidate that the nitrogen-doped monolayer MoS2 possesses intense hybridization between Mo-d states and N-p?and S-p?states,thus inducing the evolution of magnetism as verified by experiments.We developed an in-situ method to nitrogen-doping during monolayer MoS₂ nanoflakes chemical vapor deposition?CVD?synthesis.Experimental measurements demonstrate that our as-synthesized nitrogen-doped MoS₂ monolayers are room-temperature and air-stable ferromagnetic semiconductors,which are high desirable for semiconductor spintronic applications.Our work discloses the possibility to enable the magnetism to atomically thin semiconductors by nitrogen-doping and highlights the potential of 2D magnetic materials for future magnetoelectric applications.