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The magnetism-induced ferroelectricity in the E-type orthorhombic HoMnO3 (o-HMO) films grown on Nb-doped and undoped SrTiO3(001) substrates was studied. The temperature dependent magnetization in these films evidently exhibits an antiferromagnetic ordering around 44 K and an anomalous second magnetic ordering along the c-axis near 35 K. Interestingly, at this anomalous transition temperature, an associated ferroelectric polarization was probed by the P-E hysteresis measurements, indicating the intimated coupling between the ferroelectric response and the reordering of Mn spins, which has never been disclosed previously by dielectric constant measurements. [ABSTRACT FROM AUTHOR]

Orthorhombic YMnO3 thin films with (200), (020), and (001) orientations were, respectively, obtained by pulsed laser deposition on SrTiO3(110), LaAlO3(110), and SrTiO3(001) substrates. The results demonstrate that the strain between film and substrate can serve as an alternative in transforming the thermodynamically stable hexagonal YMnO3 into the orthorhombic phase, which previously could be obtained with high-pressure high temperature syntheses and epitaxy-stabilized thin film processes. More importantly, these films allow us, for the first time, to unambiguously disclose the intrinsic magnetic property along different crystallographic orientations. Our results show that, although the antiferromagnetic (AFM) ordering remains the same, there is an additional spin reordering transition which is very much dependent on the crystallographic orientation along which the measuring field was applied and on the in-plane crystallographic alignment of the films. Detailed analyses indicate that the origin of the observed second reordering may be due to some strain-induced canted AFM state instead of the incommensurate lock-in transitions conceived previously. [ABSTRACT FROM AUTHOR]

Single-phase electron-doped manganite thin films with nominal composition of La0.7Ce0.3MnO3 (LCeMO) have been prepared on SrTiO3 (100) substrates by pulsed laser deposition. The conditions for obtaining purely single-phase LCeMO films lie within a very narrow window of substrate temperature (Ts∼720 °C) and laser energy density (ED∼2 J/cm2) during deposition. In situ postdeposition annealing, mainly to relax the possible epitaxial in-plane tensile strain between the film and the substrate, leads to an increasing c-axis lattice constant accompanied by the formation of secondary CeO2 phase and higher metal-insulator transition temperature. This is indicative of a strong coupling between the electron and lattice degree of freedom. [ABSTRACT FROM AUTHOR]

We report the growth of high quality topological insulator Bi2Se3 thin films on a single layer, transitional metal dichalcogenide MoS2 film via van der Waals epitaxy in a planar geometry. In stark contrast to the reported growth of using 3-D crystalline substrates such as Al2O3(0001), Bi2Se3 thin films grown on a 2-D template made of single layer MoS2 showed excellent crystallinity starting immediately from the growth of the first quintuple layer. Excellent crystallinity of Bi2Se3 thin films is attained, with the increased size of the triangular shaped Bi2Se3 domains and 2–3 times enhancement in mobility, along with the observation of Shubnikov–de Haas oscillations in the magnetoresistance. Our approach of adopting a van der Waals type template may be extended to the thin film growth of other low dimensional layered materials. [ABSTRACT FROM AUTHOR]

Amorphous Si thin films have been prepared using radio-frequency magnetron sputtering. Cu nanodots of 2-10 nm in diameter were sputter deposited on the surface of Si films. The Si films modified with Cu nanodots (n-Cu/Si) were used as anodes for lithium-ion batteries. The performances of the n-Cu/Si anodes with different thickness of Si films, 120 and 1000 nm, were characterized and compared. The Cu nanodots can greatly improve the cycling stability. The amount of capacity fading was 66% after 150 cycles for the thinner Si films (120 nm), and was over 90% after 50 cycles for thicker films (1000 nm). For the n-Cu/Si films, the amount of capacity fading was 33% for thin films and 45% for thicker films. [ABSTRACT FROM AUTHOR]

Abstract: High-quality heteroepitaxial LaNiO3 (LNO) thin films were successfully grown on SrTiO3 (STO) substrates with RF-magnetron sputtering deposition at substrate temperatures in a range 150–650°C. Azimuthal scans around the surface Bragg peak of the film and lattice images from a high-resolution transmission electron microscope (HRTEM) show that a well epitaxial relationship between film and substrate is achievable through RF sputtering growth. BaTiO3/SrTiO3 (BTO/STO) artificial superlattices subsequently deposited on LNO-coated STO substrates with RF sputtering were found also to have a large dielectric constant and a small dissipation factor. [Copyright &y& Elsevier]

Abstract: We have studied the structure of a high-porous silica thin film with pore sizes in nanometer scale using X-ray reflectivity and small angle X-ray scattering in grazing incidence geometry. The reflectivity data provide the information of surface and interface characteristics, density–depth profile, and porosity of the xerogel film. Whereas the grazing incidence small angle X-ray scattering results reveal the internal structure of the porous film, including pore shape and size, and averaged inter-pore spacing. It is demonstrated that the combination of these two techniques is a powerful structural characterization tool to porous thin films. [Copyright &y& Elsevier]

Cubic phase yttrium-doped HfO2 (YDH) ultrathin films were grown on Si (111) substrates by molecular beam epitaxy. Thorough structural and morphological investigations by x-ray scattering and transmission electron microscopy reveal that the YDH thin films are epitaxially grown on the Si substrates with (111)YDH∥(111)Si and [101]YDH∥[110]Si. The interface between YDH and Si is atomistic sharp and free of interfacial layer. We have also determined the yttrium content of YDH films to be 19% by using anomalous x-ray diffraction (AXD) across Y k edge and angle resolved x-ray photoelectron spectroscopy (AR-XPS). The agreement between the AXD and AR-XPS results manifests that the incorporated Y atoms homogeneously substitute Hf atoms in the crystalline lattice and form a substitutional solid solution. [ABSTRACT FROM AUTHOR]

We demonstrate a mode of thin film growth in which amorphous islands crystallize into highly oriented platelets. A cascade of crystallization is observed, in which platelets growing outward from a central nucleation point impinge on neighboring amorphous islands and provide a seed for further nucleation. Through control of growth parameters, it is possible to produce high quality thin films which are well suited to the formation of organic transistors. We demonstrate this through the fabrication of rubrene thin film transistors with high carrier mobility. [ABSTRACT FROM AUTHOR]

The authors have fabricated NaxCoO2 thin films via lateral diffusion of sodium into Co3O4 (111) epitaxial films (reactive solid-phase epitaxy [Ohta et al., Cryst. Growth Des. 5, 25 (2005)]). The environment of thermal diffusion is key to the control of the sodium content in thin films. From the results of x-ray diffraction and in-plane ρab, the epitaxial growth and the sodium contents of these films were identified. The thermoelectric measurements show a large thermoelectric power similar to that observed in single crystals. The quasiparticle scattering rate is found to approach zero at low temperatures, consistent with the small residual resistivity, indicating high quality of the NaxCoO2 thin films. [ABSTRACT FROM AUTHOR]

Abstract: A set of polyaniline- and poly(3,4-ethylene dioxythiophene)-based materials were studied as hole injection layers in polymer light emitting devices. The choice of polymeric counterion/dopant poly(styrenesulfonic acid), and poly(acrylamido-2-methyl-1-propanesulfonic acid), and poly(acrylamide) blended with polyaniline/poly(acrylamido-2-methyl-1-propanesulfonic acid) was found to influence both work function and film morphology, which in turn affects device performance. The work functions of the polymer films spanned the range of over 1eV and the surface region of the films were found to be low in conducting polymer content compared to the bulk. This was particularly the case of the polyaniline/poly(acrylamido-2-methyl-1-propanesulfonic acid) blended with poly(acrylamide) which showed device efficiency equal to that of the poly(3,4-ethylene dioxythiophene)–poly(styrenesulfonic acid) reference. The turn on voltage, however, was significantly larger, likely due to the insulating poly(acrylamide)-rich surface region of the polyaniline/poly(acrylamido-2-methyl-1-propanesulfonic acid)/poly(acrylamide) film. The polymer blend of polyaniline/poly(styrenesulfonic acid) yielded the highest work function (5.5±0.1eV). [Copyright &y& Elsevier]

X-ray reflectivity and high-resolution X-ray diffraction measurements were employed to characterize the microstructure and morphology of buried layers and the interfacial structure of Ru films on Si substrates prepared by radio frequency magnetron sputtering technique. Extremely highly c-axis orientated Ru films were obtained at substrate temperatures ranging from 400 to 700 °C. The presence of oscillation fringe in the diffuse scattering indicates that the conformal relationship exists between the Ru surface and the film/substrate interface in high temperature deposition. The films deposited at temperatures ≥600 °C exhibited clear interference fringes on the high-resolution X-ray diffraction measurements around the (0 0 2) diffraction peak. The pronounced interference fringes show not only a highly c-axis orientation of the layers but also a rather smooth surface and interface. The as-deposited films have extremely good texture with very smooth surface when deposited at high temperature. The full-width at half-maximum (FWHM) of ∼1° was obtained for the films deposited at high temperature. High temperature deposited Ru films have a lowest electrical resistivity of ∼11 μΩ cm. [Copyright &y& Elsevier]

We report the growth of high quality topological insulator Bi2Se3 thin films on a single layer, transitional metal dichalcogenide MoS2 film via van der Waals epitaxy in a planar geometry. In stark contrast to the reported growth of using 3-D crystalline substrates such as Al2O3(0001), Bi2Se3 thin films grown on a 2-D template made of single layer MoS2 showed excellent crystallinity starting immediately from the growth of the first quintuple layer. Excellent crystallinity of Bi2Se3 thin films is attained, with the increased size of the triangular shaped Bi2Se3 domains and 2–3 times enhancement in mobility, along with the observation of Shubnikov–de Haas oscillations in the magnetoresistance. Our approach of adopting a van der Waals type template may be extended to the thin film growth of other low dimensional layered materials. [ABSTRACT FROM AUTHOR]

Abstract: We report spectroscopic evidence for orbital-mediated phases in strained thin films by combining soft X-ray spectroscopy and synthesis of manganite thin films. Measurements of polarization-dependent soft X-ray absorption reveal that electronic states responsible for the lowest-energy excitations in C-type antiferromagnetic films have an orbital symmetry of , while those in A-type AFM films have an orbital symmetry of . Such orbital polarizations in strained films of manganite result from a combined effect of the Jahn–Teller distortion and the electron correlations of Mn 3d electrons. [Copyright &y& Elsevier]

Abstract: Na x CoO2 (x∼0.68) thin films were fabricated on sapphire (0001) substrates via the lateral diffusion of sodium into Co3O4 (111) films, which were grown by pulsed-laser deposition. From the results of X-ray diffraction and in-plane resistivity ρ ab, the single phase and the metallic behaviors of these Na x CoO2 films can be identified. For the same sodium content x, ρ ab is consistent with that of single crystals. In addition, the O 1s X-ray absorption near edge spectra of thin films are measured and compared with those of single crystals. [Copyright &y& Elsevier]