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Grazing incidence x-ray diffraction and reflectivity measurements were carried out on ultrathin (a few unit cells thick) superconducting heterostructures, based on Ba0.9Nd0.1CuO(sub 2+x) and CaCuO2 individual blocks, using undulator radiation from a third-generation synchroton. This analysis shows that the interfaces between the different constituent blocks are very sharp with roughness less than one unit cell.

We have grown LaMnO3 thin films on (001) LaAlO3 substrates by pulsed laser deposition. X-ray diffraction confirms that the films are only slightly relaxed and are oriented “square on square” relative to the substrate. The measured Raman spectra closely resemble that observed in bulk LaMnO3, which indicates no relevant distortions of the MnO6 octahedra induced by the epitaxial strain. Therefore, no detectable changes in the lattice dynamics occurred in our LaMnO3 strained films relative to the bulk case. 55Mn nuclear magnetic resonance identifies the presence of localized Mn4+ states. Superconducting quantum interference device magnetization measures TN=131(3) K and a saturation moment μ=1.09μB/Mn, revealing a small concentration of Mn4+ and placing our films within the antiferromagnetic insulating phase. [ABSTRACT FROM AUTHOR]

In this paper, we illustrate an approach to discriminate between epitaxial strain and other factors responsible for the decrease of the metal–insulator transition temperature (TP) in thin La0.7Sr0.3MnO3 films grown by pulsed laser deposition. Using this approach, we have estimated the effect of the biaxial strain on TP. Ultrathin films, independent of epitaxial strain, do not show any metal–insulator transition over the full temperature range. This finding confirms the existence of an interface dead layer. The strain-independent decrease in TP, relative to its bulk value, observed for a much wider thickness range (up to about 1000 Å) can most likely be attributed to oxygen deficiency. [ABSTRACT FROM AUTHOR]

Thin films of LaMn[O.sub.3] (LMO) compounds were prepared by pulsed laser deposition and characterized through x-ray diffraction measurements. The study demonstrates that the epitaxial strain does not induce relevant tilting or rotation of the Mn[O.sub.6] octahedra enough to influence the observed Raman spectra, which did not show any sizable shift or broadening of peaks relative to the typical bulk spectra.

An approach to discriminate between epitaxial strain and other factors responsible for the decrease of the metal-insulator transition temperature (T(sub p)) in thin La(sub 0.7)Sr(sub 0.3)MnO(sub 3) films grown by pulsed laser deposition is presented. The effects of the biaxial strain on T(sub p) are estimated by using this approach.