Microstructure and Magnetic Properties of Ni:ZnO Nanorod/Zn:NiO Nanowall Composite Structures

The microstructure, growth mechanism, and ferromagnetic (FM)/antiferromagnetic (AFM) coupling have been discussed in Ni:ZnO nanorod/Zn:NiO nanowall composite structures. The composite structures were synthesized by a hydrothermal method at 90 °C. A systematic investigation of high-resolution transmission electron microscopy, X-ray absorption spectroscopy, and magnetization studies reveals that the as-synthesized product shows FM behavior at room temperature, whereas the annealed sample shows mixed (FM/AFM) magnetic behavior. A detectable magnetic exchange coupling between FM/AFM has been demonstrated by magnetization measurements in the annealed products. The observed room-temperature FM behavior in these nanostructures was interpreted in terms of bound magnetic polarons.