Engineering half-metallicity in wurtzite Zn_1-2x Mn _x A _x S (A = Mo, Ni) for enhanced optoelectronic and thermoelectric performance: a DFT study

The electronic, magnetic, optical, and thermoelectric properties of the artificially engineered (Mn, Mo) and (Mn, Ni) codoped ZnS systems have been investigated using density functional theory (DFT) within the Wien2K Package. Calculations were carried out using both the generalized gradient approximation (GGA) and the modified Becke-Johnson (mBJ) potential to ensure reliable electronic and magnetic descriptions. The double codoping of ZnS with (Mn, Mo) and (Mn, Ni) leads to the formation of an artificial half-metallic material, where both parallel and antiparallel spin configurations converge toward a ferromagnetic solution. However, the most stable phase corresponds to a ferrimagnetic configuration. The half-metallic character originates from strong p-d hybridization between transition-metal orbitals, which plays a crucial role in determining the material's multifunctional properties. The optical response exhibits a noticeable redshift in the absorption edge and distinct plasmonic structures, demonstrating the potential of such half-metallic systems for optoelectronic and photonic applications. Furthermore, thermoelectric calculations reveal that (Mn, Mo) codoping induces a p-type Seebeck coefficient with a figure of merit (ZT) ≈ of 1.2. In contrast, (Mn, Ni) codoping exhibits n-type behaviour with an enhanced ZT ≈ 1.6. These results highlight that (Zn_1-2x Mn _x A _x S) (A = Mo, Ni) represents a promising artificial half-metallic material with significant potential for multifunctional spintronic, optoelectronic, and thermoelectric applications.