Correlations Between Lattice Vacancies and Ferromagnetism in Mn‐Doped ZnO Nanorods

We have investigated the effects of Mn doping and lattice vacancies on the structure and magnetic properties of chemically synthesized ZnO nanorods for d ⁰ ferromagnetism. Energy‐dispersive X‐ray spectroscopy analysis confirms that Mn composition X in ZnO nanorods with 80–198 nm in diameter and 0.477–2.10 μm in length increases from 0.29% to 4.1% with increasing the initial doping level of Mn from 5% to 30% in the synthesis. X‐ray photoelectron spectroscopy analysis shows that the oxygen vacancy concentration V _O in the crystal increases with increasing the synthesis temperature T _syn from 333 to 353 K. On the other hand, photoluminescence measurements suggest that the zinc vacancy concentration V _Zn increases with X . Furthermore, magnetic measurements reveal that all the samples exhibit ferromagnetic hysteresis at 1.8 and 300 K, where the saturation magnetization M _S varies with V _O , suggesting that the oxygen vacancies play an important role in the observed ferromagnetism. In addition, it is revealed that in Mn‐doped ZnO nanorods, M _S increases with increasing both V _O and X . This is presumably due to an increase in magnetic moments originating from paired defects at oxygen and zinc lattice sites V _O – V _Zn, in addition to the moment from Mn ²⁺ .