71 research outputs found
Strain-driven elastic and orbital-ordering effects on thickness-dependent properties of manganite thin films
We report on the structural and magnetic characterization of (110) and (001)
La2/3Ca1/3MnO3 (LCMO) epitaxial thin films simultaneously grown on (110) and
(001)SrTiO3 substrates, with thicknesses t varying between 8 nm and 150 nm. It
is found that while the in-plane interplanar distances of the (001) films are
strongly clamped to those of the substrate and the films remain strained up to
well above t=100 nm, the (110) films relax much earlier. Accurate determination
of the in-plane and out-of-plane interplanar distances has allowed concluding
that in all cases the unit cell volume of the manganite reduces gradually when
increasing thickness, approaching the bulk value. It is observed that the
magnetic properties (Curie temperature and saturation magnetization) of the
(110) films are significantly improved compared to those of (001) films. These
observations, combined with 55Mn-nuclear magnetic resonance data and X-ray
photoemission spectroscopy, signal that the depression of the magnetic
properties of the more strained (001)LCMO films is not caused by an elastic
deformation of the perovskite lattice but rather due to the electronic and
chemical phase separation caused by the substrate-induced strain. On the
contrary, the thickness dependence of the magnetic properties of the less
strained (110)LCMO films are simply described by the elastic deformation of the
manganite lattice. We will argue that the different behavior of (001) and
(110)LCMO films is a consequence of the dissimilar electronic structure of
these interfaces.Comment: 16 pages, 15 figure
Investigation of the effect of Au2O3 dopant on elastic properties of PbO-B2O3-SeO2: Er2O3 glass ceramics by ultrasonic techniques
Various elastic coefficients of Au2O3 doped PbO-B2O3-SeO2:Er2O3 (PBSE) glass
ceramics were evaluated as functions of Au2O3 content using ultrasonic velocity
measurements. The elastic coefficients and micro-hardness showed a decreasing
tendency with the concentration of Au2O3. Such decrease is attributed to the
increasing concentration of gold metallic particles and [SeO3]2- groups that
acted as modifiers and induced imperfections in these samples. Obtained results
were observed to be consistent with the conclusions drawn from spectroscopic
studies that include X-ray photoelectron spectroscopy (XPS), infrared (IR),
photoluminescence (PL) and positron annihilation (PAL) spectroscopy studies.
Overall, these studies have revealed that even though, the presence of gold
metallic particles is preferable for achieving superior luminescence and
electrical properties, presence of such particles caused to decrease the
elastic coefficients and micro-hardness of these glass ceramics. However, when
the concentration of Au2O3 is increased beyond 0.075 mol%, we have observed a
slight increase of elastic coefficients and micro-hardness.Comment: 6 pages, 8 figure
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