Enhancement of saturation magnetisation through the addition of a nonmagnetic element in substitutional Fe-doped In₂O₃ powder

Iron-doped indium oxide is a promising material for spin electronics (spintronics) applications. Herein, an experimental investigation of the effect of adding a nonmagnetic element (magnesium) on the enhancement of the room-temperature ferromagnetism in substitutional iron-doped In₂O₃ powder was conducted. A new doping process, which avoids the formation of Fe nanoclusters in (In_0.85Fe_{0.15− x}Mg_x)₂O₃ (x = 0.00, 0.01, 0.03, 0.05) powders, was developed. The resulting powders were characterised by X-ray diffraction (XRD), superconducting quantum interference device, Mössbauer spectroscopy, energy-dispersive spectroscopy, and X-ray photoelectron spectroscopy. The XRD analysis revealed that Fe and Mg ions were incorporated into the In³⁺ sites in the In₂O₃ lattice without altering the cubic bixbyite structure. Magnetic measurements indicated the coexistence of ferromagnetic and paramagnetic phases. Room-temperature ferromagnetic behaviour with remarkable enhancement of the saturation magnetisation was observed for decreasing Fe ions and increasing nonmagnetic Mg concentrations. Mössbauer spectra confirmed the coexistence of ferromagnetic (sextet) and paramagnetic (doublet) phases, with a clear effect of Mg concentration. The enhancement in the magnetic moment with increasing Mg doping is attributed to the large defects and oxygen vacancies induced in In₂O₃ by Fe and Mg co-doping. These results will be useful for the development of Fe-doped In₂O₃ semiconductor materials for advanced applications.