Electronic and Magnetic Properties of Defected Monolayer WSe2 with Vacancies.

By adopting the first-principle methods based on the density functional theory, we studied the structural, electronic, and magnetic properties of defected monolayer WSe2 with vacancies and the influences of external strain on the defected configurations. Our calculations show that the two W atom vacancies (VW2) and one W atom and its nearby three pairs of Se atom vacancies (VWSe6) both induce magnetism into monolayer WSe2 with magnetic moments of 2 and 6 μB, respectively. The magnetic moments are mainly contributed by the atoms around the vacancies. Particularly, monolayer WSe2 with VW2 is half-metallic. Additionally, one Se and one W atom vacancies (VSe, VW), two Se atom vacancies (VSe-Se), and one W atom and the nearby three Se atoms on the same layer vacancy (VWSe3)-doped monolayer WSe2 remain as non-magnetic semiconducting. But the impure electronic states attributed from the W d and Se p orbitals around the vacancies locate around the Fermi level and narrow down the energy gaps. Meanwhile, our calculations indicate that the tensile strain of 0~7% not only manipulates the electronic properties of defected monolayer WSe2 with vacancies by narrowing down their energy gaps, but also controls the magnetic moments of VW-, VW2-, and VWSe6-doped monolayer WSe2.