Raman study of metal-insulator transition in NdNiO3 thin films

NdNiO3 is known to undergo a metal-insulator transition at 200 K. Thin films of NdNiO3 are synthesized on LaAlO3 single crystal and Si by RF sputtering magnetron, and subsequent annealing under oxygen pressure. The metal-insulator transition investigated by a temperature study of the resistivity appears at 150 or 200 K depending on the deposition process. The films have been studied by Raman scattering from 60 K to room temperature, and strong evolution of the spectra are observed. These investigations show significant changes of frequencies and intensities at several temperatures that suggest structural changes in the vicinity of the metal-insulator transitions. (C) 2000 Elsevier Science B.V. All rights reserved.