Influence of Mn ions concentration on optical and magnetic properties of Mn-doped ZnS nanowires

• Optical and magnetic property of ZnS:Mn2+ are tuned by Mn2+ doping concentration.
• Optimized Mn2+ concentration is 3% for obtaining good optical/magnetic property.
• Competition of antiferromagnetic/ferromagnetic exchange determines magnetism.

sWe successfully synthesized the ZnS:Mn2+ nanowires (NWs) with different Mn2+ doping concentration by the simple hydrothermal method. The optical and magnetic properties can be well tuned by the Mn2+ doping concentration. The yellow–orange emission from the Mn2+ 4T1–6A1 transition can be observed in the PL spectra of ZnS:Mn2+ NWs and the intensity reaches a maximum when the concentration of Mn2+ is 3%. The room-temperature magnetic hysteresis loops of the ZnS:Mn2+ NWs indicate that when the Mn2+ doping concentration is smaller than 3% (x≤3%)，the samples exhibit the ferromagnetism characteristics; meanwhile, once the Mn2+ doping concentration is higher than 3% (x>3%), the samples exhibited a ferromagnetism including part paramagnetic characteristics at room-temperature. This variation tendency can be well explained by the competition mechanism between two exchange interactions, i.e. the antiferromagnetic exchange interaction between the near neighbor Mn2+ and Mn2+ ions, and the ferromagnetic exchange interaction between the Mn2+ and Mn2+ ions mediated by their near neighbor S2− ions or native defects such as S vacancies.

The optical and magnetic properties of ZnS:Mn2+ nanowires are tuned by Mn2+ concentration. The magnetic variation is ascribed to the competition between antiferromagnetic and ferromagnetic exchange interactions. Figure optionsDownload as PowerPoint slide