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Abstract: Pulsed-laser-deposited polycrystalline BaTiO3/SrTiO3 multilayered films on Pt/Ti/SiO2/Si substrates have been fabricated with interfacial modification through lowering the oxygen pressure during the time interval in between two adjacent depositions. It is found that the formation of the heterolayered structure is essential to get the dielectric enhancement. Such heterolayered films have large dielectric constant of 1201 with a loss tangent below 0.1 at 10KHz. This is about two times that of the identically prepared Ba0.5Sr0.5TiO3/Ba0.5Sr0.5TiO3 homolayered and uniform Ba0.5Sr0.5TiO3 films. The enhancement of dielectric properties is attributed to the presence of the interfacial regions with controllable space charges due to the formation of oxygen vacancies at lower oxygen pressure. [Copyright &y& Elsevier]

• The electronic phase separation has been observed in La 0.8 Sr 0.2 MnO 3. • The state of magnetic skyrmion exists in the temperature region of 290 K–306 K. • A large DM interaction exists in the interface of LaMnO 3 /SrMnO 3. Magnetic skyrmions, being one of the most promising candidates for the next generation memory-type application due to their nanometer-size and efficient current-driven dynamics, are mainly found and studied in alloy helimagnets in which the spin-orbit coupling induced by Dzyaloshinskii-Moriya interaction (DMI) enables noncollinear spin alignment and skyrmion formation. In this paper, we report a possible finding of skyrmions crystal near room-temperature in centrosymmetric structures perovskite manganite La 0.8 Sr 0.2 MnO 3 (LSMO). Based on the measurements of isothermal magnetization around the Curie temperature (∼298 K), an unusual magnetic behavior of a discontinuous magnetization was observed and existed only at moderate magnetic field region together with a narrow temperature range from 306 to 290 K. Apart from this range, all curves return to conventional magnetic behavior of continuous change with external magnetic field. This characteristic has been frequently observed in some reported helimagnets (such as FeGe, MnSi), implying the possible existence of skyrmions crystal in LSMO. To further unveil the physical origin and underlying mechanisms, we performed the first-principles calculation for LSMO compound and a large DMI (Δ E DMI = 13.46 meV, d 1 = 1.68 meV) was found to exists at the interface of LaMnO 3 / SrMnO 3 layers. This result not only supports our experimental findings in the present composition but also is consistent with the formation mechanism of magnetic skyrmions. [ABSTRACT FROM AUTHOR]

Wide bandgap semiconducting perovskite La:BaSnO 3 is a promising candidate for next-generation transparent conducting oxides due to its high electron mobility and excellent oxygen stability. In this work, in order to realize flexible optoelectronics, an epitaxial growth of Ba 0.96 La 0.04 SnO 3 (BLSO) film on a flexible mica via van der Waals epitaxy is established. The high quality heteroepitaxy and crystallinity of BLSO films are confirmed by a combination of X-ray diffraction and atomic force microscopy. Results show that the flexible BLSO films not only retain a high transmittance of more than 85 % in the visible region under unbending conditions, but also exhibit a remarkable transmittance of 90 % under bending conditions. Due to the fixed lattice mismatch and misfit strain, an anomalous electronic transport behavior, showing as a continuous enhancement of resistivity dependence on the decreasing temperatures from high to low, was observed for all BLSO films. Although the resistivity of flexible BLSO films is a slight larger than that of growth on rigid counterparts, the resistivity of 7–10 m Ω  cm is also satisfied with actual application for optoelectronic devices at room-temperature. Our study marks that the technological advancements toward realizing flexible optoelectronics are promising by utilizing perovskite oxides La-doped BaSnO 3 and mica substrate. [ABSTRACT FROM AUTHOR]

In this study, we investigated the structural, magnetic phase transition, and magnetocaloric properties of bilayer perovskite manganite La 1.38 Sr 1.62 Mn 2 O 7 based on X-ray diffraction, electron paramagnetic resonance, and temperature-/magnetic field-dependent magnetization measurements. The structural characterization results showed the prepared sample had a tetragonal structure with the space group I 4/ mmm . The Curie temperature was determined as 114 K in the magnetization studies and a second-order paramagnetic-ferromagnetic transition was confirmed by the Arrott plot, which showed that the slopes were positive for all the curves. According to the variation in the electron paramagnetic resonance spectrum, we detected obvious electronic phase separation across a broad temperature range from 220 to 80 K in this magnetic material, thereby indicating that the paramagnetic and ferromagnetic phases coexist above as well as below the Curie temperature. Based on a plot of the isothermal magnetization versus the magnetic applied field, we deduced the maximum magnetic entropy change, which only reached 1.89 J/kg.K under an applied magnetic field of 7.0 T. These theoretical investigations indicated that in addition to the magnetoelastic couplings and electron interaction, electronic phase separation and anisotropic exchange interactions also affect the magnetic entropy changes in this bilayer manganite. [ABSTRACT FROM AUTHOR]

In this paper, we reported a detailed study of magnetic properties and magnetic entropy change of nanocrystalline La 0.5 Sr 0.5 MnO 3 . A rigorous measurement of dc magnetization and isothermal magnetization confirm the presence of paramagnetic–ferromagnetic phase transition at 340 K and the formation of spontaneous magnetization in T < T C regime. We found that the obtained magnetic entropy change strongly decreases on reduction of samples size down to nanoscale due to the change of magnetostructural phase transition and magnetic homogeneity. Therefore, the magnetocaloric effect is inevitably tuned by the reduction of particle size. The magnetic phase transition observed in this sample was testified to be second-order by the critical exponent analysis and the systemical magnetic interaction could be understood with mean-field theory. Based on the values of magnetic entropy change under different magnetic fields, we can estimate the spontaneous magnetization which shows an excellent agreement with that deduced from the Arrott curves, indicating that the method to determine spontaneous magnetization with a mean-field analysis of the magnetic entropy change is valid for the material with second order phase transitions. [ABSTRACT FROM AUTHOR]