Substrates with crystallographic orientation (100), consisting of (100)CeO–{(100)SrTiO3–(100)CeO2} × 4 epitaxial multilayer films oriented perpendicular to the surface, have been obtained by solid-phase bonding of Y-ZrO2 fianite crystals. The CeO2 and SrTiO3 layers were exposed on the film surface by their (100) planes and the (110) faces, respectively. All formed layers were 40 nm thick. Films of high-temperature superconductor (HTSC) YBa2Cu3O7 were epitaxially grows on the substrates; a packet of parallel grain boundaries, oriented perpendicular to the surface, was formed as a result of their inheritance from the {SrTiO3–CeO2} boundaries of the multilayer internal film. The YBa2Cu3O7 film is oriented by its (001) plane and (103) face above the CeO2 and SrTiO3 regions, respectively. Thus, a packet of eight parallel 45° grain boundaries, spaced by 40 nm, is formed in the YBa2Cu3O7 film. The current–voltage characteristic of a lithographic straight-line bridge in the HTSC film intersecting this packet contains eight steps, which correspond to eight bicrystal Josephson junctions, spaced by 40 nm and connected in series.

A film of high-temperature superconductor (HTSC) YBa 2 Cu 3 O 7 has been grown on the (100) crystallographic plane of SrLaGaO 4 crystal using pulse laser deposition. An X-ray diffraction (XRD) analysis has shown that this film is single-crystal, single-domain, and oriented in the (100) plane. The superconducting transition occurs at 88.8 K and has a width of 1.6 K. Measurements of the temperature dependence of electrical resistance in these films revealed a significant anisotropy of superconductivity in the (100) plane. Due to this specific feature, the critical superconducting-transition temperature, found by measuring the temperature dependence of resistance in the film plane oriented parallel to the CuO planes, exceeded the corresponding value obtained by the same measurement in the direction perpendicular to these planes by 2 K. In addition, it is revealed experimentally that the normal resistance in the former case is smaller than in the latter case by a factor of about 400.

Films in the form of superlattices with alternating La0.7Ca0.3MnO3 layers, possessing colossal magnetoresistance, and dielectric MgO layers have been grown on MgO(100) crystals by pulse laser deposition. The growth conditions for these films, providing La0.7Ca0.3MnO3 layers in the form of nanoislands (i.e., quantum dots (QDs)), are determined. It is shown that, despite the very large (for epitaxial growth) lattice mismatch of 8% for the deposited materials, these nanoislands are characterized by a single-crystal structure. Notably, the crystallographic orientation of the magnetic-layer lattice unambiguously corresponds to that of the MgO crystal, on which they were grown. In addition, it is established that these nanoislands tend to be self-organized with the formation of clusters, within which they form elements of a two-dimensional lattice.

Substrates consisting of five parallel planar grain boundaries (GBs), oriented perpendicular to the surface and spaced by several micrometers, have been grown by solid-phase bonding of fianite crystals in order to obtain large complexes of closely spaced bicrystal Josephson junctions based on high-temperature superconductor (HTSC) films. The substrates had a crystallographic orientation (100) and dimensions of 1.0 × 10.0 × 10.0 mm3. All GBs were of symmetrical type, and their lattices were rotated by 12° in opposite directions around the axis perpendicular to the surface. The distance between GBs in a packet complex was 15 µm, and this value was maintained with an error of no more than 1 µm along their entire length of 10 mm. The deviation of the shape of all five GBs from an ideal geometric plane was within 1 µm along their entire length. Films of HTSC YBa2Cu3O7 with inheritance of GBs were grown on these substrates. Structures of two types were formed on the films using lithography. It is shown that the use of these fianite substrates in HTSC-based devices of cryogenic electronics increases significantly the density of bicrystal Josephson junctions; reduces several times the total length of superconducting lines connecting these junctions; and, correspondingly, decreases significantly the inductive resistance of these circuits and improves their electrical characteristics in comparison with the structures having similar functions but based on one or two parallel GBs.

Epitaxial YBa 2 Cu 3 O 7 films with CuO plane tilted with respect to the surface have been grown on crystalline MgO substrates by pulsed laser deposition. Directly before growing a film, a nucleation-center-forming SrTiO 3 sublayer with an effective thickness less than the unit-cell size was deposited on the substrate. The tilt angle was varied in the range from 0° (at which CuO planes are oriented parallel to the surface) to 70°. The film lattice rotation is implemented at this tilt due to the substrate rotation around its [100] axis, oriented parallel to the surface. Zero tilt of the CuO plane occurs when the MgO crystal surface is oriented parallel to the (100) plane. It is found that the CuO film planes remain parallel to one or several crystallographic planes {100} of the substrate at any tilt angles. In the range of angles from 0° to 41° the film is a single crystal. At angles larger than 41° the film is transformed into a two-domain texture, and its surface roughness sharply increases.

The anomalous plastic creep of sapphire crystals in the temperature range of 1890–2050°С, which includes their melting point, has been studied. A method is developed for maintaining crystal in the state of crystal–melt phase transition for a long time, sufficient for carrying out and finishing mechanical tests. Crystal deformation was performed in the creep mode under uniaxial compression along the [10$$\bar {1}$$2] direction. A sharp (stepwise) increase in the creep rate is found when reaching the melting point: it becomes more than an order of magnitude higher as compared with that at near-melting point temperatures. A hypothesis is proposed to explain the found phenomenon by the existence of a transition state between the solid and liquid phases of aluminum oxide, which is characterized by lattice conservation at a sharp increase in the self-diffusion rate.

Bicrystal substrates, in which (100) planes in both single-crystal parts are rotated with respect to the surface by different angles around the [100] and [110] directions (parallel simultaneously to both the surface and bicrystal boundary), have been fabricated by solid-phase intergrowth on SrTiO3 crystals. Epitaxial bicrystal YBa2Cu3O7 films with different tilt angles of CuO planes to the surface have been grown on these bicrystals by pulsed laser deposition. The structure of these films has been investigated by X-ray diffraction. The films are shown to remain epitaxial when the film lattice is rotated from the position in which its (001) plane is oriented parallel to the surface by angles of up to 41° and 49° around the [100] and [110] axes, respectively. The possibility of growing bicrystal films of YBa2Cu3O7 high-temperature superconductor (HTSC), in which the CuO planes at different sides of the bicrystal boundary make different angles (up to 90°, which is the maximum possible angle from the symmetry point of view), has been demonstrated based on these data.

Twin-free b-oriented YBa2Cu3O7 – x films with a thickness less than 40 nm have been epitaxially grown on (100)SrLaGaO4 crystals. Based on the temperature dependence of resistance, the onset temperature of the transition to the superconducting state is found to be 90 K; the transition width is 4 K. The film growth has been performed in two stages. A (100)PrBa2Cu3O7 – x buffer layer was previously grown on a (100)SrLaGaO4 substrate by rf magnetron sputtering in an Ar–O2 gas mixture at a continuous and monotonic increase in temperature from 660 to 830°C. The main YBa2Cu3O7 – x film was grown on the buffer layer surface by pulsed laser deposition in an oxygen medium at a fixed temperature (800°C). The above processes were implemented in different chambers, which were connected by a vacuum channel for transporting samples. Both films were grown in situ, without contacting atmosphere in all growth stages. An X-ray diffraction study has shown that the YBa2Cu3O7 – x films are single-crystal and free of precipitates of other phases and domains of other orientations.

The structure of Fe1 + δTe1 − x Se x films (x = 0; 0.05) grown on single-crystal MgO and LaAlO3 substrates has been investigated by transmission and scanning transmission electron microscopy. The study of Fe1.11Te/MgO structures has revealed two crystallographic orientation relationships between the film and substrate. It is shown that the lattice mismatch between the film and substrate is compensated for by the formation of misfit dislocations. The Burgers vector projection is determined. The stresses in the film can partially be compensated for due to the formation of an intermediate disordered layer. It is shown that a FeTe0.5Se0.5 film grown on a LaAlO3 substrate is single-crystal and that the FeTe0.5Se0.5/LaAlO3 interface in a selected region is coherent. The orientation relationships between the film and substrate are also determined for this case.

It is demonstrated that in the [La0.67Ca0.33MnO3(d = 9 nm)/La0.67Sr0.33MnO3(9 nm)](3) and [La0.67Ca0.33MnO3(9 nm)/SrTiO3(2 nm)/La0.67Sr0.33MnO3(9 nm)](3) superlattices with the interlayer barriers of nonmagnetic dielectric SrTiO3, the magneto-optical Kerr and magnetorefraction (magnetoreflection and magnetotransmission of unpolarized light) effects have large values close to those for the heterostructures of the same composition. The defects and strain in the layers and at interfaces of superlattices result in appearance of additional band in the Kerr effect spectrum, temperature hysteresis, and abnormal temperature dependence of the Kerr effect. It is shown, that the resonant-like contribution to the magnetoreflection spectra of superlattices is due to the shift of the minima in reflection coefficient near the phonon bands by magnetic field. The increase in magnetotransmission of superlattices relative to a single layered film is due to multiple transmission of light through the layers of superlattices. The intermixing effects at interfaces and deviations of composition of layers from stoichiometry both influence the values of magnetorefraction effect in superlattices and the shapes of their temperature dependences. (C) 2014 Elsevier Ltd. All rights reserved.

Thin films of iron-based chalcogenide superconductors FeSe0.92, with iron partially replaced (at least up to 10 at %) by elements such as cobalt, nickel, manganese, or copper, have been grown on the surface of \((10\bar 12)\) LaAlO3 crystals. Growth is performed by the laser ablation of a target prepared in the form of a ceramic pellet by high-temperature synthesis and the sintering of preliminarily pressed stoichiometric mixture of powders. Iron in these ceramics is replaced with an alloying metal by no more than 3 at %. The rest (7 at %) of the metal is in the form of precipitates of other phases. X-ray diffraction analysis of the grown films has shown that they are single-crystal and free of any precipitates of other crystallographic orientations and phases. This is evidence of the complete (10 at %) replacement of iron with a doping metal in the film structure. This circumstance indicates that the synthesis of components occurs more actively and completely during laser ablation (than in solid-phase chemical reactions) as a result of the transformation of multicomponent target material into plasma. Thus, one can fabricate film materials in a wider range of chemical compositions than in the form of solid-phase synthesized ceramics.

Thin films of FeSe0.92 and FeSe0.5Te0.5 iron chalcogenide superconductors and solid solutions containing these components in different ratios have been grown on the surface of LaAlO3 (10\(\bar 1\)2) crystals by pulsed laser deposition. Films of solid solutions have been deposited by simultaneous laser ablation from two targets of the FeSe0.92 and FeSe0.5Te0.5 stoichiometric compositions onto one substrate. An X-ray diffraction study of the film structure shows that the films grown are epitaxial and their lattice parameters regularly vary with the ratio of the deposited components, which was controllably varied by changing the ablation intensities from the targets.