The work that we present has been devoted to the study of high quality perovskitic La-Sr-Mn-O (LSMO) thin films. More than two hundreds samples were deposited by RF magnetron sputtering in Ar + O₂ atmosphere. Under suitable conditions, the films have the same cation stoichiometry as the target (that is, La_0.7Sr_0.3MnO₃), as demonstrated by Rutherford backscattering. They are also smooth, as Scanning Tunnel measurements (STM) show.

We investigated various substrates, i.e. SrTiO₃ (STO), LaAlO₃ (LAO), NdGaO₃ (NGO), with both (001) and (110) crystallographic orientations. We always observed the cube-on-cube structure that is typical of epitaxial growth of perovskites on perovskites. However, the difference in the lattice matching with substrate leads to films that are subject to compressive stress on LAO, and tensile stress on STO and, to a less extent, on NGO. The strained structure has been investigated resorting to x ray reciprocal space mapping (RSM). Although previous studies already unveiled some details of (001) strained LSMO, the data regarding (110) films are new. The lattice deformation in this case is peculiar, because it is partially due to shear stress. This feature is particularly interesting in the LSMO manganite, because it is well known that the magnetic and the transport properties of this compound strongly depend on strain, due to the complex interplay between lattice, electronic and magnetic degrees of freedom. Here we report on the comparison between the hysteresis loops of LSMO grown on (001) and (110) STO. In both cases, the magnetic properties are strongly related to the stress. The stress also influences the transport properties. The resistivity of films grown on (110) STO is anisotropic, and it is slightly higher than that of films on (001) STO. The possible relations between magnetism, stress and transport properties are object of the discussion of the experimental results.

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1. Structural, 1/f noise and MOKE characterization of vicinal La_0.7Sr_0.3MnO₃ thin films