Ferromagnetism and spin polarization in indium nitride, indium oxynitride, and Cr substituted indium oxynitride films

We have investigated the structural, electrical, and magnetic properties of both sputter deposited indium oxynitride and Cr substituted indium oxynitride films as well as InN films grown by molecular beam epitaxy. The degenerate oxynitride films exhibit n-type carrier concentrations in excess of 1020 cm−3 and remain conducting to low temperatures, while the InN samples have much lower carrier concentrations and are insulating at low temperatures. At the same time all of these films show a room temperature ferromagnetic signal, with saturation magnetization ranging from 0.05 emu cm−3 for the indium oxynitride and InN films to 0.30 emu cm−3 for the Cr substituted film. Low temperature point contact Andreev reflection measurements find a spin polarizations from 46 ± 2% for indium oxynitride to 50 ± 2% for the Cr substituted films. These results highlight the potential of nitrides for spintronic applications.