Fabrication and properties of ReTiO3+δ/2 (Re = La and Nd) thin films

ReTiO3+δ/2 (Re = La and Nd) thin films have been grown on (1 0 0)SrTiO3 and (1 0 0)LaAlO3 by using the pulsed laser deposition technique. Oxygen content in the films was tuned by adjusting the oxygen pressure during film growth. At higher pressures, the films tend to be in their fully oxidized insulating form ReTiO3.5 with a twinned structure and (012-bar) orientation. Grown in vacuum, the films are lightly doped with a small δ, and retain the near-cubic perovskite structure. The films grown on different substrates show distinct magnetic and transport properties, which cannot be fully attributed to the conducting SrTiO3 substrates or the interdiffusion. In metallic films, a decrease of the carrier density and an increase of the Hall mobility at low temperatures was observed, and the transport behaviors can be fitted by a small-polaron coherent conduction model (Rs(T) = Rs(0) + Cωα/sinh2(Tω/T))