  Perpendicularly magnetized spin injector with high Curie temperature is a
prerequisite for developing spin optoelectronic devices on 2D materials working
at room temperature (RT) with zero applied magnetic field. Here, we report the
growth of Ta/CoFeB/MgO structures with a large perpendicular magnetic
anisotropy (PMA) on full coverage monolayer (ML) MoS2. A large perpendicular
interface anisotropy energy of 0.975mJ/m2 has been obtained at the CoFeB/MgO
interface, comparable to that observed in magnetic tunnel junction systems. It
is found that the insertion of MgO between the ferromagnetic metal (FM) and the
2D material can effectively prevent the diffusion of the FM atoms into the 2D
material. Moreover, the MoS2 ML favors a MgO(001) texture and plays a critical
role to establish the large PMA. First principle calculations on a similar
Fe/MgO/MoS2 structure reveal that the MgO thickness can modify the MoS2 band
structure, from an indirect bandgap with 7ML-MgO to a direct bandgap with
3ML-MgO. Proximity effect induced by Fe results in a splitting of 10meV in the
valence band at the {\Gamma} point for the 3ML-MgO structure while it is
negligible for the 7ML-MgO structure. These results pave the way to develop RT
spin optoelectronic devices on 2D transition-metal dichalcogenide materials.
