We systematically measure and analyze x-ray absorption fine structure and the anomalous Hall effect of recently discovered room-temperature ferromagnetic semiconductor thin films, ${\left({\mathrm{In}}_{1-x-y}{\mathrm{Fe}}_x{\mathrm{Cu}}_y\right)}_2{\mathrm{O}}_{3-\sigma }$. The x-ray fine structure demonstrates that divalent Fe ions exist in ferromagnetic samples but not in nonmagnetic ones, suggesting a mobile-electron-mediated ferromagnetism. The anomalous Hall behavior is found to be consistent with that of ferromagnets, in which carriers are delocalized, but qualitatively different from that of double-exchange manganites, in which carriers are bound to magnetic ions, confirming that the ferromagnetism in ${\left({\mathrm{In}}_{1-x-y}{\mathrm{Fe}}_x{\mathrm{Cu}}_y\right)}_2{\mathrm{O}}_{3-\sigma }$ is mediated by mobile electrons.

• Received 31 March 2005

DOI:https://doi.org/10.1103/PhysRevB.74.165321