The magnetic properties of FexZn1-xO synthesized via the solid-state reaction route: Experiment and theory

We report on a study of magnetism of Fe-doped ZnO powders and tablets synthesized via the solid-state reaction route. The X-ray diffraction results indicate that the solid solubility of Fe in ZnO was less than 1%. When the concentration of Fe was more than 2%, a second phase of ZnFe2O4 was detected. All samples were ferromagnetic in the room temperature and the Hall effect was observed. Calculations based on the density functional theory (DFT+U) indicated two origins for the observed ferromagnetism. The first source is considered to occur due to the second phase of the inverse spinel-type ZnFe2O4 where the antiferromagnetic states of the Fe2Zn14O16 system were preferred through Fe2+ -O2--Fe2+ or Fe3+ -O2- -Fe3+ bonding. The second appears to originate from the ferromagnetic states of the Fe2Zn14O16 system with the Fe3+ -O2--Fe2+ bond. The bond is suggested to form due to the double exchange interaction with the Fe2+ and Fe3- ions substituting the Zn2+ ions in the ZnO lattice, yielding an intrinsic ferromagnetic oxide semiconductor. (C) 2013 Elsevier B.V. All rights reserved.