Effect of Fe2+/3+ doping on the new magnetic mechanism and itinerant electronic characteristics of ZnO

Abstract

Fe2+/3+ doping has been experimentally proven to have ferromagnetic effects on ZnO. However, the source and mechanism of magnetic properties are still explained by using the traditional double exchange theory with oxygen atoms as the intermediary. Therefore, the theoretical explanation of these phenomena needs to be expanded urgently. In this study, first principles calculations are used to investigate the effect of Fe2+/3+ doping on the magnetic mechanism of ZnO on the basis of the generalized gradient approximation plane wave ultrasoft pseudopotential method within the framework of spin density functional theory. This study shows that the Zn34Fe2O36(Fe3+) system exhibits the characteristics of ferromagnetism above room temperature and that the total magnetic moment is not an integer when the distance between two Fe ions is 4.790 Å. The Zn34Fe2O36(Fe3+) system has a part of O1− ions in addition to O2− ions, that is, it contains the characteristics of itinerant electrons (donors) and local electrons (acceptors). This study is the first to discover that Fe3d states also produce local and itinerant electrons. It also reveals a new magnetic mechanism for sp–d double exchange with itinerant electrons as the media in the Zn34Fe2O36(Fe3+) system.