Identifying valency and occupation sites of Ir dopants in antiferromagnetic α-Fe₂O₃ thin films with X-ray absorption fine structure and Mössbauer spectroscopy

A combined analysis of Ir-doped α-Fe₂O₃ (001) films, which show a drastic enhancement in the Morin transition temperature as a result of Ir doping, was performed by employing X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and Mössbauer spectroscopy analyses at room temperature. The Mössbauer spectra reveal that the valency of Fe remains 3+ after Ir doping. The XANES spectra indicate that the valency of the Ir ion in Ir-doped α-Fe₂O₃ varies from 3+ to 4+. The EXAFS analysis results clarified that the Ir ions occupy the Fe-sites of α-Fe₂O₃. These findings help elucidate the mechanism for controlling the Morin transition temperature in α-Fe₂O₃ films toward antiferromagnetic spintronic applications.