Strain engineering the magnetic states of vacancy-doped monolayer MoSe₂

The effect of vacancy defect and strain on the magnetic property of monolayer MoSe₂ was investigated by the first-principles calculation. Firstly, the most stable structure of monolayer MoSe₂ and four kinds of vacancy, V_Se, V_Se2, V_MoSe3 and V_MoSe6 geometries were systematically studied. Our calculations show that 1H-MoSe₂, as well as V_Se, V_Se2 and V_MoSe3 vacancy doped MoSe₂ monolayer are nonmagnetic, while V_MoSe6 vacancy geometry shows magnetism and the magnetic moment mainly comes from the six Mo atoms around the vacancy although it is most difficult to form. Meanwhile, our calculations indicate that MoSe₂ monolayer under tensile strain ranging from 0% to 10% does not show any magnetism. However, it is found that the combined tensile strain and V_Se, or V_Se2 and V_MoSe3 vacancy indeed induce magnetism in MoSe₂ monolayer by breaking the Mo-Mo metallic bonds. As for V_MoSe6 vacancy geometry, the vacancy induced magnetic moment decrease under the imposed tensile strain.