Defects and strain engineering the electronic structure and magnetic properties of monolayer WSe_2 for 2D spintronic device

摘要

The electronic structure and magnetic properties of vacancy or antisite defect doped monolayer WSe2 with tensile strain from 0% to 10% were investigated systematically by using first-principles calculations. Among the unstrained defective configurations, including V-Se, V-Se2, V-W, V-W2, V-WSe3, V-WSe6 and Se-W, only the V-WSe6 complex defects display obvious spin polarization with half-metallicity and induce an amazing spin magnetic moment of 5.94 mu(B), which originates from the environment-induced W 5d orbital electron delocalization due to the loss of Se atoms. As tensile strain increases, the nonmagnetic V-Se, V-W and V-W2 defective configurations transform to the magnetic state. This transition is due to the relative change of atomic spatial position, leading to further electron delocalization as well as the alteration of bonding effects around the vacancies. It can be predicted that strain can effectively drive the occurrence of spin polarization within the pressure range that the material can withstand through facilitating electron delocalization of W atoms in the defective monolayer WSe2.