Influence of Mn doping content on magnetic properties of a (Mn, N) co-doped ZnO system

• (Mn, N) codoped ZnO films with various Mn contents were prepared.
• Room-temperature ferromagnetism was observed.
• Magnetic moments reach a limit under a certain N doping condition.
• Magnetic interactions between Mn dopants in the presence of N in ZnO were studied by first-principles calculations.
• Ferromagnetic coupling mechanism of (Mn, N) codoped ZnO has been discussed.

In this paper, by investigating the magnetic properties of (Mn, N) co-doped ZnO films with various Mn doping contents, we found that the total magnetic moments of the samples would reach a limit under a certain N doping condition even if more Mn ions were incorporated into the ZnO lattice. Based on first-principles calculations, we propose that the unique magnetic interactions between Mn2+ dopants in the presence of nitrogen and the very low solubility of substitutional N relative to Mn in ZnO are responsible for the experimental observation.