Spin-Split Impurity States in Manganese-Doped Single-Layer Molybdenum Disulfide

Manganese-doped single-layer molybdenum disulfide (Mn-MoS₂) has been predicted to be a two-dimensional dilute magnetic semiconductor (DMS). We present scanning tunneling microscopy and spectroscopy data on Mn-MoS₂, in which we identify multiple impurity states associated with manganese dopants. Tip induced band bending causes ring features to appear around impurities in energy-dependent spectral maps, with some impurities exhibiting multiple rings at different energies. By quantifying the number, energies, and sizes of these charging rings, we are able to associate these impurity states with several impurity incorporation sites. By correlating this data with density functional theory calculations, we find evidence of specific impurity sites with a large energy splitting between up and down spin states. In addition to various impurity types, we identify local electronic signatures of manganese acting as both a disulfur substitutional dopant and as a molybdenum substitutional dopant, the latter a necessary precursor to the two-dimensional DMS state.