Influence of molybdenum doping on the magnetic properties of ZnS nanocrystals

Room-temperature magnetism in chalcogenide semiconductor nanomaterials is an enticing topic. Here, we report the impact of high-valence dopant molybdenum on the magnetic characteristics of zinc sulfide (ZnS) nanocrystals. Structural analysis shows that the incorporation of molybdenum does not alter the cubic phase of the host ZnS lattice except for a small decline in the crystallinity. In the ZnS matrix, the 3% molybdenum concentration results in a bandgap redshift from 3.82 (pristine ZnS) to 3.77 eV. Zinc and sulfur-related vacancies as well as surface defects that exist in the ZnS nanocrystals are confirmed using photoluminescence spectroscopy. Investigations on the magnetic characteristics of as-prepared nanocrystals at room temperature reveal mixed magnetism, with ferromagnetic characteristics at low applied fields and a diamagnetic nature at high applied fields. The maximum coercivity of 247 Oe and the lowest retentivity of 78 μemu/g were observed for the ZnS nanocrystals with 3% of molybdenum. The results of this study may open the pathway toward dilute magnetic semiconductor applications.