Ferromagnetic ordering in chemically synthesized ZnS:Mn diluted magnetic semiconductor: A density functional theory explanation

We have carried out DFT calculations to investigate the origin of room temperature ferromagnetism in experimentally obtained Mn doped ZnS magnetic semiconductor. For experimental investigations, the formation of the cubic ZnS structure of ∼4 nm in size is confirmed by XRD and TEM results. Theoretical calculations reveal that Mn doped ZnS system possesses half metallic characteristics in addition to strong p-d hybridization between the d-states of Mn atom and the p-states of surrounding S atoms, which leads to the strong ferromagnetic coupling and is experimentally realized in the M-H curves of Mn doped ZnS nanoparticles. The ferromagnetic coupling between Mn-Mn atoms are studied by using two dopant model, replacing two Zn atoms by two Mn atoms in ZnS supercell, which depicts that ferromagnetic state is always ground state. In calculating formation energies for single and two Mn dopant ZnS systems, negative values of formation energy are obtained indicating of higher stability of the system.