Defects engineering monolayer MoSe2 magnetic states for 2D spintronic device

The effects of vacancy and antisite defects, such as VMo, VMo2 far, VMo2 close, VSe, VSe2 close, VMoSe3, VMoSe6 and MoSe2 on the electronic structure and magnetic properties of monolayer MoSe2 were systematically investigated using the density functional theory calculation. The theoretical results indicate that the single Mo vacancy (VMo) induces a large magnetic moment of 3.939 μB and shows magnetic half-metallicity due to the Se unsaturated dangling bond around the Mo vacancies. Effective n-type doping can be achieved by the creation of Se vacancy (VSe and VSe2). However, the Se vacancy doped systems are nonmagnetic due to the formation of Mo-Mo metallic bonds around the Se vacancies, which results in the disappearance of Mo unsaturated dangling bonds. The VMoSe3 and VMoSe6 complex defects as well as MoSe2 antisite defect have high formation energy of defects. The VMoSe3 remains nonmagnetic. However, the VMoSe6 and MoSe2 defects induce a magnetic moment of 5.74 μB and 1.92 μB, respectively, which originates from the unpaired 4d electrons between the nearest-neighbor Mo atoms. These results show that the vacancies can engineer the electronic structure and magnetic properties of monolayer MoSe2, which makes it become novel candidates for photo-catalysis, photoluminescence and spintronic devices.