Electronic and magnetic properties of Ag-doped monolayer WS2 by stain

Electronic and magnetic properties of Ag-doped WS2 monolayer subject to isotropic strain are investigated using first-principles calculations. Our results show that the Ag-doped WS2 is half-metallic material with without strain. As strain changed, the Ag-doped WS2 transforms from half-metallic to metallic. But compressive strain comes to -10%, it transform from metallic to half-metallic. The intrinsic band gap gradually decreases with increasing isotropic strain. Moreover, the tensile strain appears to be more effective in reducing the band gap of Ag-doped WS2 monolayer than compressive strain. The half-metallic (HM) gap increases first and then decreases quickly with increasing compressive strain from 0 to 5%, but the half-metallic gap increases gradually with increasing tensile strain from 0 to 7%. The largest half-metallic gap is 0.110 eV at 5% tensile strain, which is important for application in semi-conductor spintronics. The magnetic moment under tensile strain is enhanced from 0.817 to 1.434 mu(B). But when the compressive strain is beyond -5%, the net magnetic moment is greatly enhanced, the maximum magnetic moment comes to 3.687 mu(B) at -9% strain. The compressive strain is more effective on the magnetic moment in Ag-doped WS2 monolayer than tensile strain. The formation energy is lower under S-rich conditions, which indicates that it is energy favorable and relatively easier to incorporate Ag atom into WS2 monolayer under S-rich experimental conditions. (C) 2016 Elsevier B.V. All rights reserved.