Light-matter interactions in high quality manganese-doped two-dimensional molybdenum diselenide

Introducing magnetic dopants into two-dimensional transition metal dichalcogenides has recently attracted considerable attention due to its promising applications in spintronics and valleytronics. Herein we realized manganese-doped molybdenum diselenide (MoSe₂) single crystal via chemical vapor transport (CVT) reaction, containing up to 2.9% (atomic concentration) Mn dopants, and investigated the light-matter interaction in these samples. We observed a suppressed trion intensity, a longer photoluminescence lifetime, and prominent blue- and red-shift of E_2g² (in-plane) and A_1g (out-of-plane) Raman modes, respectively. Moreover, the Mn dopants increase the valley Zeeman splitting of the MoSe₂ monolayer by ∼50%, while preserving the linear dependence on magnetic field. First-principles calculations indicate that the spin-polarized deep level defect states are formed due to the Mn substitutional dopants in the MoSe₂ lattice. The resulting defect potential favors the funnelling of excitons towards the defects. The Mn dopants reduce the magnitude of the interatomic force constants, explaining the red-shift of the A_1g mode. The Mn atoms and their immediate Mo and Se neighbors carry significant magnetic moments, which enhance the observed exciton g-factors due to the exchange interactions affecting defect-bound excitons.