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ManQanite films; structural characterization; RBS/channelling
Abstract:
Colossal magneto resistive manganites are oxide materials where the
magnetic interactions and the electrical properties are mainly
controlled by the Mn valence ratio (+3/+4). For thin films these
properties present also a strong dependence on strain and
microstructure. In this study we focus on doped La-Sr-MnO3 and undoped
stoichiometric LaMnO3. The films were prepared by laser ablation using
stoichiometric ceramic targets and were deposited at a substrate
temperature of 770 degreesC on single crystalline SrTiO3. All the films
were submitted to the same in situ oxygen/heat treatment and the
thicknesses were in the range of 20-500 nm. Rutherford backscattering
spectrometry/channelling analysis shows the epitaxial growth of
manganite films with an excellent single crystalline quality. For fully
strained films, due to lattice mismatch with the substrate, we obtained
minimum yields of 5% measured along the [10 0] growth direction. Strain
relaxation leads to an increase of the minimum yield with the increase
of thickness. Detailed angular scans were performed in selected films
to study the misalignment along the tilt [I 10] and [I 11] directions
in order to obtain an indication on the residual strain. The results
were compared with X-ray diffraction and the correlation with respect
to the structural quality of the films is remarkable. Moreover the
magnetic measurements suggest a close relation between the transition
temperature (T-c) and the strain in the films. (C) 2004 Elsevier B.V.
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