Electronic and magnetic properties of single chalcogen vacancies in MoS₂/Au⁡(111)

Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) are considered highly promising platforms for next-generation optoelectronic devices. The performance of such 2D devices is often strongly impacted even by a minute concentration of defects. Even though defects are widely believed to have a negative influence on device performance, recently defect engineering is becoming a strategy to design new properties of 2D materials. Here, we study controllably produced single S vacancies in a monolayer of MoS₂ on Au(111). By combining scanning tunnelling microscopy and atomic force microscopy we show that this type of defect is negatively charged, which leads to the emergence of a Kondo resonance, a signature of an unpaired electron exchange coupled to the metal substrate. The strength of this exchange coupling is modulated throughout the moiré superstructure of the MoS₂ on Au(111). In areas where the MoS₂ is freestanding, the S vacancy remains charge neutral. Our results suggest that defect engineering might be used to induce magnetic properties in otherwise nonmagnetic materials.