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Epitaxial Cr2AlC MAX phase thin films were grown on MgO(111) and Al2O3(0001) by pulsed laser deposition (PLD) at 600°C. X-ray diffraction and morphology studies of Cr2AlC thin films on MgO (111) reveal phase purity, columnar growth, the epitaxial relation Cr2AlC(0001) || MgO(111) and Cr2AlC [11-20] || MgO[10-1] and similar growth behaviour on Al2O3(0001). Resistivity measurements show semiconductor-like behaviour for 10 and 20 nm thick films, and metallic-like behaviour for thicker films, suggesting a percolation thickness slightly above 20 nm. Our results demonstrate the potential of PLD as a novel method for the growth of epitaxial MAX phase thin films. Pulsed Laser Deposition is applied to grow phase pure and epitaxial Cr2AlC MAX phase thin films on MgO(111) and Al2O3(0001). Control of the sample stoichiometry is achieved by elemental targets. [ABSTRACT FROM AUTHOR]

Dynamic tuning of optical properties is technologically important for the development of future integrated electronic and photonic devices. Here, we demonstrate the electrically tunable permittivity in optical frequency in epitaxial BaTiO3 (BTO) thin films using spectroscopic ellipsometer measurements under DC bias condition. The lattice tetragonal distortion and domain switching of biased BTO is evident based on the increased anisotropy in permittivity in-plane and out-of-plane. Specifically, out-of-plane permittivity, arising from the c-domains, shows a continuous decrease with the applied voltage, relative to the in-plane permittivity, arising from the a-domains. The dielectric constant can also be reversibly adjusted through electric-reset cycles. The current study demonstrates the real-time electrically tunable dielectric permittivity in BaTiO3, probed using spectroscopic ellipsometer at optical frequencies, towards future tunable waveguides, optical components and devices. [ABSTRACT FROM AUTHOR]

Perovskite (Pr0.002Sr0.998)(Ti0.98Al0.02)O3 epitaxial thin films were obtained and showed red luminescence under ultraviolet excitation. The films were grown on SrTiO3 (001) substrates by pulsed-laser deposition, and the crystallinity of the epitaxial growth was confirmed by X-ray diffraction and reflected high-energy electron diffraction. Red luminescence of the as-grown film showed a sharp emission peak centered at 615 nm. This emission line was assigned to the intra atomic transition from the 1D2 state to 3H4 in Pr3+ ions. The transparencies of the double-side-polished substrate with and without the film at around 550 nm were about 68% and 70%, respectively. The preparation of epitaxial thin films with a red luminescence and a high transparency may open up applications for light emitting devices. [ABSTRACT FROM AUTHOR]

Antiferroelectric PbZrO3 epitaxial thin film with thickness of 50 nm grown on the SrTiO3 substrate with SrRuO3 buffer layer was studied by Grazing incidence X-ray diffraction in a wide range of temperatures. Apart from the superstructure reflections characteristic for the antiferroelectric phase, we identify the reflections with pseudocubic coordinates of the form (H + 0.5, K + 0.5, L). This indicates the presence of structures having orthorhombic symmetry as an effect of anti-phase Pb atoms displacements, which are apparently similar to the ones previously proposed for the rhombohedral high-temperature phase in PbZrxTi1-xO3. For these structures only the domain orientations with displacements parallel to the surface are observed in contrast to the antiferroelectric domains where the parallel to surface Pb displacements are absent. The antiferroelectric phase coexists with the one characterized by (H + 0.5, K + 0.5, L) reflections in a broad temperature range with the maximal amount of the latter being present at T = 150 °C. [ABSTRACT FROM AUTHOR]

In this work, a detailed investigation has been performed on hetero-epitaxial growth and microstructural evolution in highly oriented Ni–Mn–Ga (1 0 0) films grown on MgO (1 0 0) substrate using high-resolution X-ray diffraction and orientation imaging microscopy. Mosaicity of the films has been analysed in terms of tilt angle, twist angle, lateral and vertical coherence length and threading dislocation densities by performing rocking curve measurements and reciprocal space mapping. Density of edge dislocations is found to be an order of magnitude higher than the density of screw dislocations, irrespective of film thickness. X-ray pole figure measurements have revealed an orientation relationship of|| (1 0 0)MgO;|| [0 0 1]MgObetween the film and substrate. Microstructure predicted by X-ray diffraction is in agreement with that obtained from electron microscopy and atomic force microscopy. The evolution of microstructure in the film with increasing thickness has been explained vis-à-vis dislocation generation and growth mechanisms. Orientation imaging microscopy observations indicate evolutionary growth of film by overgrowth mechanism. Decrease in coercivity with film thickness has been explained as an interplay between stress field developed due to crystal defects and magnetic domain pinning due to surface roughness. [ABSTRACT FROM PUBLISHER]

La-substituted Bi4Ti3O12 (BLT) epitaxial ferroelectric thin films having a reduced number of azimuthal domains were grown by pulsed laser deposition on offcut yttria-stabilized zirconia (YSZ) single crystal substrates. Crystallographic structure and electrical properties of the films grown on offcut YSZ(100) substrates with an offcut angle of 5° have been investigated. BLT films grown on [011] offcut YSZ(100) substrates covered with SrRuO3(110) electrode layers showed a considerably higher reduction of the number of azimuthal domains than those grown on SrRuO3(110) electrode layers on [001] offcut YSZ. Higher remanent polarization values were measured in BLT films on [011] offcut YSZ(100) substrates, compared to BLT films grown on [001] offcut or exactly cut ones, most probably due to the reduced number of azimuthal domain boundaries. [ABSTRACT FROM AUTHOR]

Dielectric properties of epitaxial relaxor ferroelectric thin-film heterostructures were experimentally studied in a broad range of temperature, frequency, and amplitude of ac-field. Contribution of the film-electrode interfaces to the properties of the heterostructures was evaluated and the true properties of the films were reconstructed and analyzed. In the films, the Vögel-Fulcher relationship, deviation from Curie-Weiss behavior, temperature evolution of local order parameter, relaxation-time spectrum, and dielectric nonlinearity were found to be essentially similar to those in bulk relaxor ferroelectrics. [ABSTRACT FROM AUTHOR]