Ab-initio, Monte Carlo and experimental investigation on structural, electronic and magnetic properties of Zn1-xNixO nanoparticles prepared via sol-gel method

In this work, structural, electronic and magnetic properties of Ni doped ZnO nanoparticles (NP’s) synthesized via the sol-gel method have been investigated. Different techniques of characterization have been applied to study the Ni dependence of the microstructural, morphological, compositional and magnetic properties. As a result, X-ray diffraction analysis indicates that the obtained samples have a hexagonal Wurtzite structure with preferential orientation along (101). The increase of Ni concentration leads to a size reduction of the nanoparticles. Also segregated Ni clusters have been observed by SEM/EDX. The magnetization field (M − H) curves reveal the existence of ferromagnetism in Ni-doped ZnO at room temperature. First principle calculations based on density functional theory are applied to study the effect of Ni doping on the structural, electronic and magnetic properties of ZnO, allowing for a deeper understanding for the experimental findings. The obtained results indicate that Ni doped ZnO with less than 8.33% Ni present long-range ferromagnetic ordering. Furthermore, Ni doped ZnO is antiferromagnetically stable at 12.5%. Monte Carlo simulation based on heat bath algorithm coupled with DFT results have been used to validate the proposed explanation for the magnetic behavior of the experimental part. Therefore, the obtained results indicate that Ni doped ZnO is a good candidate as a diluted magnetic semiconductor due to its high exchange coupling interaction that leads to a high Curie temperature.