Strain-dependent electronic and magnetic properties of Au-doped WS2 monolayer

• Au doping induces magnetism in the WS2 monolayer.
• Band gap gradually decreases with increasing isotropic strain.
• The maximum magnetic moment (3.736μB) is observed with -9% strain.
• Strain-induced Au-doped WS2 monolayer can be a 2D Diluted magnetic semiconductor.

Using first-principles calculations, we investigated electronic and magnetic properties of Au-doped WS2 monolayer with strain from −10% to 10%. The results show that the band gap gradually decreases with increasing isotropic strain including compressive and tensile strain. Moreover, the tensile strain appears to be more effective in reducing the band gap of Au-doped WS2 monolayer than the compressive strain. The magnetic moment under tensile strain is enhanced from 0.813 to 1.167μB. But when the compressive strain is beyond −5%, the net magnetic moment is greatly enhanced, the maximum magnetic moment comes to 3.736 μB at −9% strain, nearly five times of the original moment 0.813 μB. The compressive strain is more effective on the magnetic moment in Au-doped WS2 monolayer than the tensile strain. Strain changes the redistribution of charges, and the hybridization of between the d orbital of Au atom, d orbital of W atom and p orbital of S atom, induces to magnetic moment. Moreover, the formation energy is lower under S-rich conditions, which indicates that it is energy favorable and relatively easier to incorporate Au atom into WS2 monolayer under S-rich experimental conditions. Our calculation show that the strain-induced Au-doped WS2 monolayer can be a two dimension Diluted magnetic semiconductor (DMS) at −9% strain.