Probing magnetism and electronic structure of Fe-doped ZnO thin films

• The KKR–CPA approach was used to study the magnetism of Fe-doped ZnO thin films.
• There is a competition between p–d exchange and superexchange mechanisms leading to weak ferromagnetic and antiferromagnetic contributions.
• Zn vacancies are more significant than the O ones for obtaining ferromagnetism.

Ab-initio calculations using Korringa–Kohn–Rostoker method combined with the coherent potential approximation were performed in order to study the magnetic properties of Fe-doped ZnO thin films with different Fe contents. The extracted parameters are compared with those determined experimentally. Based on total and partial densities of state curves, we demonstrate that there is a competition between p–d exchange and superexchange mechanisms leading to weak ferromagnetic and antiferromagnetic contributions, respectively. The dominant mechanism is found to be antiferromagnetic. However, with increasing Fe content the ferromagnetic contribution increases. In addition, the effect of structural defects on the magnetism of the system is reported. It is shown that both Zn and O vacancies increase ferromagnetism, which is more pronounced in case of Zn.