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Due to epitaxial strain, epitaxial thin films exhibit unique properties compared with those in bulk. However, the presence of defects within these films disrupts the strain-induced effects. Although high-temperature annealing is a promising way to improve film quality, high temperature weakens bottom electrode materials. To assess epitaxial strain's effects on the mitigation of other factors, there is a need for a novel bottom electrode material that can withstand high temperatures. In this study, we focused on Nb-doped CaMnO3 (CMNO) as a bottom electrode for the evaluation of BaTiO3 ferroelectricity. The CMNO epitaxial film was deposited on (100)SrTiO3 and showed electrical conductivity even after 1100 °C annealing. The ferroelectric material BaTiO3 was also epitaxially grown on CMNO/(100)SrTiO3 substrate, and its ferroelectric properties were evaluated. Finally, we revealed the ability of CMNO/(100)SrTiO3 to withstand temperatures up to 1100 °C as well as the notable enhancement of ferroelectric properties in the BaTiO3 film. [ABSTRACT FROM AUTHOR]

To control the properties of multiferroic materials, substitution of magnetic elements is a useful technique. In this study, we fabricated GaCrxFe1−xO3 and Ga1−yCryFeO3 films by substituting Cr3+ (3d3) ions in GaFeO3 for magnetic Fe3+ (3d5) and nonmagnetic Ga3+ (d10) sites, respectively. The effect of the Cr substitution on the magnetic and dielectric properties was systematically investigated. The obtained GaCrxFe1−xO3 and Ga1−yCryFeO3 films (x ≤ 1/4 and y ≤ 1/2) simultaneously exhibit ferrimagnetism and ferroelectricity. For the GaCrxFe1−xO3 films, the magnetic transition temperature (TC) and magnetic anisotropy decrease with increasing x. On the other hand, for the Ga1−yCryFeO3 films, TC increases with increasing y. Unlike the GaFeO3 film, the Cr-substituted GFO films show a peak in the magnetization versus temperature curves and exhibit a sudden decrease in the coercive field near the peak, probably due to the formation of Fe3+–O–Cr3+ coupling which prefers to form ferromagnetic interactions in the antiferromagnetic Fe3+–O–Fe3+ networks. Furthermore, we found that the Cr-substituted GaFeO3 films show out-of-plane ferroelectricity at room temperature. [ABSTRACT FROM AUTHOR]

The macroscopic electromechanical behavior of lead-free multilayer composites was characterized from room temperature to 150 °C. The polar seed component consisted of a nonergodic relaxor (Bi1/2Na1/2)TiO3-7BaTiO3, with an electric-field-induced long-range ferroelectric order, whereas the nonpolar matrix was an ergodic relaxor Bi0.5(Na0.75K0.25)0.5 TiO3-6BiAlO3 that undergoes a reversible electric-field-induced macroscopic nonpolar-to-polar transition. Microstructural evidence of the effects of cosintering are demonstrated through examination of grain size, interdiffusion, and pore structure. By manipulating the sintering interactions between the two constituents, namely, diffusion paths and residual stresses, both internal mechanical and electrical fields, as well as compositional gradients can be used to enhance the unipolar strain over that expected by a rule of mixtures approximation, thereby improving the properties needed for application of such materials to actuator systems. [ABSTRACT FROM PUBLISHER]

Tetragonal Pb(Zr, Ti)O3 films were epitaxially grown on SrRuO3-coated SrTiO3 substrates by metal organic chemical vapor deposition. Perfect polar-axis-oriented 50 nm thick tetragonal films were successfully grown on (100)SrRuO3//(100)SrTiO3 substrates. The single phase of the tetragonal symmetry region was expanded to a Zr/(Zr + Ti) ratio of around 0.6 for these films but was reduced to around 0.4 when (100)/(001)-mixture oriented 250 nm thick films were obtained. The dependence of spontaneous polarization (Ps) on the lattice parameter of c-axis to a-axis (c/a ratio) was demonstrated using perfectly polar-axis-oriented films with various Zr/(Zr + Ti) ratios. The 250 nm thick (100)/(001), (110)/(101), and (111)-oriented tetragonal films were grown on (100), (110), and (111)-oriented substrates. The domain structure was analyzed in detail, and it was found that the observed saturation polarization (Psat) value can be explained by the Ps value and the 90° domain contribution. These data clearly demonstrate the importance of epitaxial film research for actual ferroelectric random access memories applications. [ABSTRACT FROM AUTHOR]

Thin films of Bi(Fe1-xScx)O3 (BFSO) system were fabricated on (111)Pt/TiO2/SiO2/(100)Si substrates by chemical solution deposition to improve the electrical resistivity by substituting electrically unstable Fe3+ cations for stable Sc3+ cations. A single phase of perovskite was obtained in the range of x=0–0.30, in which selective replacement of Fe3+ and Sc3+ was confirmed in x=0–0.15 by using Raman measurement. The leakage current density of the BFSO films was reduced by increasing x. A well-saturated polarization–electric field hysteresis loop was obtained for BFSO films with x=0.15, showing remanent polarization of approximately 35 μC/cm2. [ABSTRACT FROM AUTHOR]

Abstract: GaFeO3‐type iron oxide is a promising room‐temperature multiferroic material due to its large magnetization. To expand its usability, controlling the ferroelectric and magnetic properties is crucial. In this study, high‐quality GaxFe2–xO3 (x = 0–1) epitaxial films are fabricated and their properties are systematically investigated. All films exhibit room‐temperature out‐of‐plane ferroelectricity, showing that the coercive electric field (Ec) decreases monotonically with x. Additionally, the films show in‐plane ferrimagnetism with a Curie temperature (TC) >350 K at x = 0–0.6. The coercive magnetic field (Hc) decreases with x at x ≤ 0.6, but shows a constant value at x > 0.6, whereas the saturated magnetization (Ms) increases with x at x ≤ 0.6, but decreases with x at x > 0.6. X‐ray magnetic circular dichroism reveals that the large magnetization at x = 0.6 is derived from Fe3+ (3d5) at octahedral sites. The controllable range of the Ec, Hc, and Ms values at room temperature (400–800 kV cm−1, 1–8 kOe, and 0.2–0.6 µB/f.u.) is very wide and differs from those of well‐known multiferroic BiFeO3. Furthermore, the GaxFe2−xO3 films exhibit room‐temperature magnetocapacitance effects, indicating that adjusting TC near room temperature is useful to achieve large room‐temperature magnetocapacitance behavior. [ABSTRACT FROM AUTHOR]