N codoping induced room temperature ferromagnetic enhancement in (Fe, N)-codoped In2O3 films by experimental and computational insights

The (Fe, N)-codoped In2O3 films with cubic bixbyite structure have been prepared by magnetron sputtering methods. A combination of the XRD, XPS with X-ray absorption spectroscopy techniques reveals that the codoped Fe and N impurities were substitutionally dissolved at In and O sites of the In2O3 lattice, respectively, and form FeIn + 2VO complex in the first coordination shell of Fe. The Mott variable-range hopping (VRH) conduction mechanism was observed to dominate at the low temperature region, which is accompanied by an obvious room-temperature ferromagnetic behavior for both the films, while the N codoping remarkably enhances the saturated magnetization (Ms) of the (Fe, N)-codoped In2O3 film. Based the first principles calculations, it was found that N codoping in the (Fe, N)-codoped In2O3 film can change the magnetic coupling between two Fe ions from antiferromagnetic to ferromagnetic due to the strong N 2p-Fe 3d hybridization interaction. It can be concluded that the indirect interaction between bound magnetic polarons (BMP) based oxygen vacancies as well as the Fe-N-Fe ferromagnetic superexchange interaction may be responsible for the intrinsic ferromagnetic ordering in the (Fe, N)-codoped In2O3 film. These results may provide a new sight for understanding the magnetic mechanism of In2O3 based DMS systems.