InN films were grown by N<sub>2</sub> plasma-assisted molecular beam epitaxy (MBE) on Al<sub>2</sub>O<sub>3</sub> substrates. The films were characterized by reflection high-energy electron diffraction, atomic force microscope, x-ray diffraction methods and Raman spectrum, indicating high crystalline quality of the films. The optical absorption and photoluminescence measurement show the band-gap energy of InN films was located about 1.0-1.1 eV.
InN-based diluted magnetic semiconductor (DMS) In<sub>1-x</sub>Mn<sub>x</sub>N and In<sub>1-x</sub>Cr<sub>x</sub>N films were prepared by N<sub>2</sub> plasma-assisted MBE at low temperature. Microstructure characterization indicates Mn was homogeneously incorporated into InN up to 4% and 10% respectively at 300°C and 200°C, while Cr was incorporated up to 4% at 300°C. A paramagnetic to spin-glass transition was observed at 3 K in In<sub>0.9</sub>Mn<sub>0.1</sub>N films grown at 200°C. Room temperature ferromagnetism was observed for the homogeneous In<sub>0.98</sub>Cr<sub>0.02</sub>N films.
Transition metal doped III-V nitrides including Mn- or Cr-doped GaN and InN are grown by molecular beam epitaxy (MBE). Structural, electronic and magnetic properties have been investigated. Cr-doped GaN shows room temperature ferromagnetism. Bulk sensitive high-energy x-ray photoemission spectroscopy is performed at SPring-8 to elucidate electronic structure of Cr-doped GaN. It is found that the doped Cr contributes to form gap states, which pin the Fermi level. The gap state is attributed to Ga 4<i>s</i> originated state caused by strong hybridization between Cr 3<i>d</i> and band electrons of host GaN. InN-based system were grown by low temperature MBE. Highly Mn-doped InN shows spin-glass states. Anti-ferromagnetic interaction between Mn ions in InN was suggested. Contrary to the Mn-doped InN, Cr-doped InN shows ferromagnetic property at room temperature.
Pr<sub>1-x</sub>Sr<sub>x</sub>MnO<sub>3</sub> (100) thin films were prepared on NdGaO<sub>3</sub> (100) substrate by RF-plasma-assisted molecular beam epitaxy method. The films were characterized by reflection high-energy electron diffraction, atomic force microscope and x-ray diffraction methods, indicating perfect surface smoothness and high crystalline quality. Large low field magnetoresistance effects with strong anisotropic properties of the non-stoichiometric (Pr<sub>1-x</sub>Srx)yMnO<sub>3</sub> films have been observed. These results may be connected with the large A-site deficient in the films.