Modified Becke-Johnson potential calculations of Co-substituted MgS alloys for spintronic and optoelectronic applications

Abstract

Herein, first principles computations are employed to examine the effect of concentrations dependent cobalt doping on geometrical stability, magneto-electronic, and optical properties of MgS. All Co-MgS configurations are geometrically and thermodynamically stable. Pristine MgS is nonmagnetic semiconductor with mBJ predicted bandgap of 3.9 eV. Spin-resolved DFT analysis reveals that Co doping induces spin polarization leading to the asymmetric spin dependent electronic properties. Lightly doped Co-MgS alloy show dilute magnetic semiconducting state, while densely doped Co-MgS systems show half metallic ferromagnetic state. Co-3d state along S-3p states contribute to the emergence of ferromagnetic phase, confirmed by the computed total and localized magnetic moments and iso-surface spin density visualizers. Additionally, the optical parameters including absorption, scattering, refraction and dielectric function of respective alloys have been explored. Peak values of absorption were found at 5.8–6.4 eV energy range in ultra-violet (UV) region for Mg_0.9375Co_0.0625S, Mg_0.875 Co_0.125S alloys. The highest absorption and low reflectivity in UV zone along with dilute magnetic semiconducting and half metallicity with ferromagnetic ordering make these alloys an appropriate option for optoelectronic and spintronic applications.