Magnetic ion implantation: A defect-assisted mechanism for concurrent control of doping-induced magnetism and excited state dynamics of single-crystalline MoS₂

In few-layered MoS₂, frequent occurrence of defect-assisted scattering, non-radiative carrier recombination and presence of mid-gap traps are detrimental to the lifetime of the excited-states. Additionally, the weak magnetic attributes of MoS₂ restricts its application in magneto-optics or spin-transport. In this work, using Fe and Mn ion implantation, we demonstrate a simultaneous control of the magnetism and excited-state optical properties of single-crystalline MoS₂. Different concentrations of magnetic doping were accomplished by varying the fluence of the Mn and Fe ion beams. XPS measurements indicate the systematic variation of doping and the corresponding shift of the core-level spectra. These systems exhibit a long-range magnetic ordering below 100 K. Transient absorption measurements have pointed out a significant increase of the life-time of both excitons  for an optimal doping percentage. The presence of the stark shifts/blue-shifts are ascribed to the increase in the exciton-exciton repulsion with increasing delay time. In the light of the first-principles calculations on multi-layered MoS₂ in presence of the intra-plane, inter-plane and interstitial magnetic impurities and point defects like S or Mo vacancies, we have analyzed our experimental observations.