Enhanced transport properties in LaxMnO3 thin films grown on SrTiO3 substrates

We report on structural, magnetic, and transport properties of La(x)MnO(3-delta) thin films, epitaxially grown on SrTiO(3) substrates by molecular beam epitaxy deposition technique. We varied the La/Mn ratio by changing the evaporation rate of the single-element diffusive cells. However, the oxygen content of La(x)MnO(3-delta) thin films was varied by post-annealing them in air and/or vacuum, by changing the annealing temperature and the time of post-annealing process. Optimal oxygenated La(0.88)MnO(3-delta) (LMO) films show extremely high metal insulator transitions temperature T(MI) similar to 380K and magneto-transport similar to those found in strontium-doped La(1-x)Sr(x)MnO(3) manganites compounds. Magnetic measurements confirm the formation of a ferromagnetic phase at Curie temperature T(c) of about 360K. All these findings clearly demonstrate that the lanthanum deficiency, with respect to bivalent cation-substitution, is a very efficient way to hole-dope manganites.