Improving the magnetic, electronic and optical properties of the monolayer WSe2 via Mn-X (X = O, S, Se or Te) codoping

Abstract

The structural, magnetic, electronic and optical properties of the pure and Mn-X (X = O, S, Se or Te) codoped monolayer WSe2 systems are quantitatively examined through first-principles calculations. The lower formation energy under Se-rich condition shows that the codoped systems under Se-rich condition is more stable than W-rich condition, especially the Mn-O codoping is the most stable with the minimum formation energy -2.08 eV. Although the pure monolayer WSe2 is a nonmagnetic semiconductor, the codoped systems are all magnetic with total magnetic moments of 1.00 µB due to the introduced one unpaired electron. It is worth mentioning that the Mn-Se and Mn-Te codoping make the monolayer WSe2 display magnetic half-metallic properties. Finally, the optical properties of the pure and codoped monolayer WSe2 are studied in x (parallel to the WSe2 plane) and z (perpendicular to the WSe2 plane) directions. An interesting red-shift phenomenon has been observed in the curves of imaginary part of the dielectric function and absorption spectra for the Mn-X codoping, suggesting their quite promising applications in optoelectronic devices.