First-principles study of oxygen vacancy concentration on multiferroics of ZnO:Co system

Abstract Currently, while there has been experimental progress in effectively modifying the multiferroicity of ZnO via doping, a corresponding understanding based on first-principles studies is still lacking. This work therefore employs first-principles calculations to investigate the multiferroic properties of ZnO with Co doping and oxygen vacancies (Vo). The results indicate that both Co doping and Vo are stable in the ZnO lattice. Under oxygen-rich conditions, the formation energies of all doped systems are lower—and indeed negative—compared to those under Zn-rich conditions. At an oxygen vacancy concentration of 1.16 × 10 21 cm −3 , the Zn 35 Co 1 O 35 system exhibits good ferroelectricity, ferromagnetism, and half-metallicity. The Co-3d states demonstrate itinerant electron characteristics. Furthermore, the Zn 34 Co 2 O 35 system meets the criteria for ferromagnetic materials that exhibit room-temperature ferromagnetism. The calculated results are consistent with existing experimental data.