Based on hybrid density-functional calculations, we propose that ferromagnetism in the prototypical bixbyite sesquioxide In2O3 doped with Cr is due to Cr-oxygen vacancy complexes, while isolated Cr cannot support carrier-mediated magnetic coupling. Our proposal is consistent with experimental facts such as the onset of ferromagnetism in O-lean conditions only, the low or vanishing net moment in unintentionally doped material, and its increase upon intentional doping.
@article{arxiv.1312.3793,
title = {Impurity-vacancy complexes and ferromagnetism in doped sesquioxides},
author = {Paola Alippi and Maura Cesaria and Vincenzo Fiorentini},
journal= {arXiv preprint arXiv:1312.3793},
year = {2015}
}