Valence state analysis of Mn and Fe ions in room-temperature ferromagnetic Mn- and Fe-codoped

The detailed valence states of Mn and Fe ions in room-temperature ferromagnetic In2O3 doped with Mn and Fe ions were investigated by the near-edge X-ray absorption fine structure (NEXAFS) measurements. It was confirmed that Mn2+ and Mn3+ coexist in In2O3. In addition to these two magnetic ions, Sn4+ was incorporated to control the charge states of doped Mn and/or Fe ions, which makes the Mn2+/Mn3+ ratio larger with an increase in the doped- Sn4+ concentration. It was found that the magnetic susceptibility decreased with an increase in Mn2+ because of the Sn4+-doping, which indicated that the coexistence of Mn2+ and Mn3+ is mandatory for room-temperature ferromagnetism in Mn- and Fe-codoped In2O3.