Enhanced transport properties in LaxMnO3-δ thin films grown on SrTiO3 substrates

We report on structural, magnetic, and transport properties of LaxMnO3-δ thin films, epitaxially grown on SrTiO3 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 LaxMnO3-δ 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 La0.88MnO3-δ (LMO) films show extremely high metal insulator transitions temperature TMI ~ 380K and magneto-transport similar to those found in strontium-doped La1-xSrxMnO3 manganites compounds. Magnetic measurements confirm the formation of a ferromagnetic phase at Curie temperature Tc 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.

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