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Layer-by-layer (LbL) assembly methods through alternative dipping processes were used to prepare hybrid nanoassemblies of 5 nm ZnO nanoparticles (ZnONPs) with catechol-functionalized polycyclosiloxane (CFPS60, 51.9 mol% catechol content). ZnONPs were assembled on solid substrates regularly and firmly through interactions with 4 nm-thick CFPS60, proved using UV-vis absorption measurements, atomic force microscopy and peel-off test. ZnONPs exhibited yellow photoluminescence (PL) in CFPS60/ZnONPs films, and the PL intensity increased notably as the number of bilayers increased. The work demonstrates that CFPS60 has a good hybrid nanoassembly formation capability, which is promising for next-generation optoelectronic device applications. [ABSTRACT FROM AUTHOR]

There is a growing interest in mixing spintronics and superconductivity to develop original energy-efficient nonvolatile memory and logic devices. Research works conducted so far have mostly focused on superconductor with critical temperature Tc lower than 10 K. Here, we report on the growth and characterization of MgB2/Ni80Fe20 and MgB2/Co bilayers, where Tc of the MgB2 layer is of the order of 30 K. Ferromagnetic resonance was undertaken to analyze the spin pumping into MgB2. The larger magnetization at saturation in Co, as compared to Ni80Fe20, induces a smaller spin pumping contribution to the damping when MgB2 is normal. A spin pumping reduction was observed for both bilayers when MgB2 becomes superconductor and is attributed to the opening of the superconducting gap. The present results show that MgB2 thin films could be suitable to implement superconducting spintronic at 30 K, which is not only relevant for future technological development but also relaxes experimental constraints related to low-temperature investigations. [ABSTRACT FROM AUTHOR]

Transition-edge sensor (TES) microcalorimeters are advanced cryogenic detectors that use a superconducting film for particle or photon detection. We are establishing a new production line for TES detectors to serve as cryogenic anticoincidence (i.e., veto) devices. These detectors are made with a superconducting bilayer of titanium (Ti) and gold (Au) thin films deposited via electron beam evaporation in a high vacuum condition on a monocrystalline silicon substrate. In this work, we report on the development of such sensors, aiming to achieve stable sensing performance despite the effects of aging. For this purpose, patterned and non-patterned Ti/Au bilayer samples with varying geometries and thicknesses were fabricated using microfabrication technology. To characterize the detectors, we present and discuss initial results from repeated resistance–temperature (R–T) measurements over time, conducted on different samples, thereby augmenting existing literature data. Additionally, we present a discussion of the sensor's degradation over time due to aging effects and test a potential remedy based on an easy annealing procedure. In our opinion, this work establishes the groundwork for our new TES detector production line. [ABSTRACT FROM AUTHOR]

Transverse thermoelectric generation converts temperature gradient in one direction into an electric field perpendicular to that direction and is expected to be a promising alternative in creating simple‐structured thermoelectric modules that can avoid the challenging problems facing traditional Seebeck‐effect‐based modules. Recently, large transverse thermopower has been observed in closed circuits consisting of magnetic and thermoelectric materials, called the Seebeck‐driven transverse magneto‐thermoelectric generation (STTG). However, the closed‐circuit structure complicates its broad applications. Here, STTG is realized in the simplest way to combine magnetic and thermoelectric materials, namely, by stacking a magnetic layer and a thermoelectric layer together to form a bilayer. The transverse thermopower is predicted to vary with changing layer thicknesses and peaks at a much larger value under an optimal thickness ratio. This behavior is verified in the experiment, through a series of samples prepared by depositing Fe–Ga alloy thin films of various thicknesses onto n‐type Si substrates. The measured transverse thermopower reaches 15.2 ± 0.4 µV K−1, which is a fivefold increase from that of Fe–Ga alloy and much larger than the current room temperature record observed in Weyl semimetal Co2MnGa. The findings highlight the potential of combining magnetic and thermoelectric materials for transverse thermoelectric applications. [ABSTRACT FROM AUTHOR]

The solid thin films of Py/Pt and Py/W heterostructures have been studied using the ferromagnetic resonance method. The temperature dependences of the Gilbert damping parameter and voltage of the inverse spin Hall effect (ISHE) have been obtained in the 5–290 K temperature range. An abnormal increase in the Gilbert damping parameter in the vicinity of 50 K and a change in the voltage of ISHE has been found. It has been concluded that an increase in the Gilbert damping parameter is of spin-orbital nature. [ABSTRACT FROM AUTHOR]

A study of peculiarities associated with the propagation of short pulses of surface magnetostatic waves in a yttrium iron garnet (YIG) thin film bilayer is presented from both an experimental and theoretical perspective. A magnetic bilayer structure has been modelled using spatiotemporal coupled mode theory, including a dispersion term for the coupling coefficient. Both the experiment and the theory show that the dispersion of the coupling coefficient plays an important role in shaping the pulse envelope and can result in the splitting of the incident pulse into two pulses. The energy exchange between the ferrite layers can be interrupted when the dispersion of the coefficient is high enough. [ABSTRACT FROM AUTHOR]

• Puled laser treatment of gold–silicon suboxide bilayers was done in air and vacuum. • The visible light, in comparison to IR pulses, destroys the samples. • The conditions for treatment without evaporation of samples was found. • The crystalline phase of silicon was obtained in air without additional oxidation. High-quality polycrystalline silicon films on low-cost and low-temperature substrates have attracted much attention as promising materials for high-speed thin-film transistors and thin-film solar cells fabrication. To obtain poly-Si films on low temperature substrates, several concepts have been proposed. Usually the amorphous material undergoes crystallization which can be achieved by various methods including solid-phase crystallization, metal-induced crystallization or liquid-phase crystallization. In this work, we tried to combine the advantages of metal-induced crystallization and liquid-phase crystallization. To achieve this we explored the nanosecond laser crystallization of a bilayer structure consisting of Au and SiO0.1 layers with thicknesses of 30 nm and 130 nm, respectively. The study reveals that when exposed to 532 nm wavelength radiation leads to its destruction due to rupture. On the other hand, when subjected to 1064 nm wavelength radiation, no similar material behavior is observed, and the measured modification threshold is 0.15 J/cm2, representing a 40 % reduction compared to SiO0.1 film without gold. It is demonstrated that at laser fluences of 0.35 J/cm2 and higher, the treated surface in air becomes enriched with silicon dioxide nanoporous coating, attributed to the return of evaporation products to the target surface. Theoretical modeling, assuming thermal evaporation of the coating, suggests that the undesirable nanoporous layer formation can be avoided. [ABSTRACT FROM AUTHOR]

The discovery of transparent electrodes led to the development of optoelectronic devices such as touchscreens, infrared (IR) sensors, etc. Carbon nanotubes (CNTs) have been a potential replacement for ITO due to their exceptional properties, especially in the IR region. In this work, we present the development of a CNT-polymer composite thin film that exhibits outstanding transparency across visible and IR spectra prepared by layer-by-layer (LbL) technique. This approach ensures uniform integration and crosslinking of CNTs into lightweight matrices, and also represents a cost-effective method for producing transparent electrodes with remarkable properties. The produced films achieved a transparency above 80 % in the UV/VIS range and approximately 70 % in the mid-IR range. The sheet resistance of the fabricated thin films was measured at about 4 kΩ/sq, showing a tendency to decrease with the number of bilayers. In this work we have investigated electrical properties and transport mechanisms in more detail with computational analysis. Computational analysis was performed to better understand the electrical behavior of nanotube-polymer junctions in the interbundle structure. Based on all results, we propose that the transparent electrodes with 4 and 6 bilayers are the most optimal structures in terms of optical and electrical properties. [Display omitted] • Optimization of SWCNT-polymer electrodes with high transparency in the UV/Vis and mid-IR range. • Simple, affordable layer-by-layer technique for the fabrication of SWCNT-polymer electrodes. • Computational analysis as a tool for more detailed investigation of electrical properties and transport mechanisms. • Proposed 4- and 6-bilayer structures as the best trade off as the best compromise between optical and electrical properties. [ABSTRACT FROM AUTHOR]

Bilayers consisting of La0.67Ca0.33MnO3 (LCMO) and SrMnO3 (SMO) have been prepared by pulsed-laser deposition on SrTiO3 (001) substrates. Unconventional magnetic coupling was found after cooling in a small field. The LCMO/SMO bilayers exhibit an exchange bias field of 209 Oe, which vanishes as the temperature rises above 90 K. A small magnetization has been found above the Curie temperature of the pure LCMO thin films. Spin-cluster-like antiferromagnetic (AFM)/ferromagnetic (FM) clusters have been deduced to exist at the interface due to the competing types of magnetic order at the interface. The magnetic relaxation is found to follow a doubleexponential equation and a slow relaxation process is observed due to the strong exchange coupling between AFM/FM clusters and the LCMO layer. We speculate that the short-range high-temperature FM order of the Mn3+ and Mn4+ moments above the Curie temperature at the interface gives rise to the magnetic regions that pin the FM LCMO layer as the temperature decreases. [ABSTRACT FROM AUTHOR]

Terrestrial accelerator facilities can generate ion beams which enable the testing of the resistance of materials and thin film coatings to be used in the space environment. In this work, a TiO 2 /Al bi-layer coating has been irradiated with a He + beam at three different energies. The same flux and dose have been used in order to investigate the damage dependence on the energy. The energies were selected to be in the range 4–100 keV, in order to consider those associated to the quiet solar wind and to the particles present in the near-Earth space environment. The optical, morphological and structural modifications have been investigated by using various techniques. Surprisingly, the most damaged sample is the one irradiated at the intermediate energy, which, on the other hand, corresponds to the case in which the interface between the two layers is more stressed. Results demonstrate that ion energies for irradiation tests must be carefully selected to properly qualify space components. [ABSTRACT FROM AUTHOR]

In this work, interlayer (Cr vs amorphous CuZr) with various thicknesses ranging from 5 nm to 40 nm were utilized for 1000 nm-thick nanostructured Cu films on polyimide substrates. The effects of heterogeneous interface and interlayer thickness on the fatigue behavior of Cu/interlayer bilayers were investigated by in situ synchrotron X-ray diffraction, electrical resistance measurement, in combination with microstructural examinations. The results demonstrated that the fatigue tolerance highly depends on the thickness and constituent of interlayer. The fatigue lifetime monotonically increases as CuZr interlayer thickness increases, coupled to the yield stress. In contrast, the fatigue lifetime first increases and then decreases with increasing Cr interlayer thickness, reaching its maximum value at a thickness of 5 nm. The underlying mechanisms for this discrepancy can be elucidated in terms of heterogeneous constraint and interface voiding, both of which depend on the interlayer thickness. [ABSTRACT FROM AUTHOR]

In this study, Cu(In1−xGax)Se2 (CIGS) thin film was deposited on molybdenum (Mo) coated glass substrate by thermal co-evaporation technique and depth profile crystal orientation of the this film was examined by grazing incidence X-ray diffraction (GIXRD) method. The crystal structure of the CIGS thin film was determined within 20° to 80° (2θ) scanning range at 0.5° to 15° incidence angle of X-ray. Cross section images were investigated by scanning electron microscope measurements and these measurements showed that bilayer Mo thickness and CIGS thickness are approximately 480 nm and 2 µm, respectively. The surface roughness of films investigated by atomic force microscopy (AFM) and average roughness Ra was found 11.07 nm. According to GIXRD measurements; the interdiffusion of the constituent elements and their effect on the crystal structure were defined both electromagnetic field penetration (skin depth) and mass attenuation viewpoints, and also these results were supported by energy dispersive spectroscopy measurements. As a result, it was seen that the GIXRD method can be used with ease to define the crystal phase homogeneity and depth profile characterization of thin film volume applying skin depth theory. [ABSTRACT FROM AUTHOR]

In this study, perpendicular exchange bias (PEB) effect in the as-grown Co49Pt51/IrMn bilayers was demonstrated at room temperature using single-layered Co49Pt51 alloy thin film as ferromagnetic (FM) layer. Several unusual features were observed in this system, viz.,: (i) the PEB was spontaneously established without any external magnetic field treatments, (ii) single-shifted loops were obtained rather than double-shifted ones, and (iii) the spontaneous PEB effect was accompanied by a reduction in perpendicular coercivity, Hc⊥ from 1024 to 632 Oe. The results of x-ray diffraction revealed the formation of IrMn (111) texture. Training effect studies indicate that the PEB effect is stable in this system with less than 5% variation in PEB value within 15 repetitive scans. Significant reduction in the PEB effect was found for the CoPt/IrMn films either grown or subjected to post-annealing under external magnetic field (Hind). The thickness dependence of PEB effect with respect to the FM and antiferromagnetic layers were also investigated and a largest PEB value of 533 Oe was obtained for the sample grown with 3-nm thick CoPt and 10-nm thick IrMn layers. The results of present study thus establish an opportunity to realize PEB effect in the absence of external field during fabrication. [ABSTRACT FROM AUTHOR]

Abstract We report on the interplay between surface morphology and the magnetic properties of Pt/Mn ultra-thin bilayers by measuring the temperature dependence of the resistivity of Hall bars cooled under application of an external magnetic field. The resistivity (ρ) versus temperature (T) curves measured under a magnetic field applied along the x -, y - and z - directions exhibit a clear difference between the zero-field-cooled (ZFC) and field-cooled (FC) traces. The disparity between the ZFC and FC traces allowed us to determine the direction of the magnetic easy-axis. The ρ vs. T characteristic of the Pt/Mn bilayers revealed the existence of antiferromagnetic (AF) order below 79 K, in agreement with the Néel temperature observed in temperature dependent susceptibility curves. We also investigated the morphological evolution of the Mn films as a function of Mn thickness by atomic force microscopy (AFM). We observed the formation of a Mn layered structure on a 2nm-thick Al 2 O 3 buffer layer for films thicker than 2.5 nm. Our results suggest that bilayer structures consisting of non-magnetic noble metals on ultra-thin antiferromagnetic metals can be used as a probe to explore the complex magnetic properties of the AF layer. Highlights • Surface magnetism of antiferromagnetic Mn films was probed using thin Pt/Mn bilayers. • Transport properties of Pt were linked to magnetic properties of Mn films. • Magnetic properties of Mn films were linked to surface morphology of Mn films. • The Néel temperature and antiferromagnetic structure at Pt/Mn interfaces were determined. [ABSTRACT FROM AUTHOR]

Abstract In this study, synthesis and characterization of plasma polymerized Thiophene/ Nickel doped Zinc Oxide (PTNZO) bilayer nanocomposite films were carried out. Nickel doped zinc oxide (NZO) thin films were obtained by magnetron sputtering technique on glass substrates at 40 W Radio Frequency (RF) power. Plasma polymerized Thiophene (PT) thin films were deposited on the NZO thin films obtained on the glass substrate by Radio Frequency (RF) plasma polymerisation technique. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), FTIR and Photoluminescence (PL) analyzes were performed for the characterization of PTNZO hetero bilayer nanocomposite films. In the XRD spectra of PTNZO bilayer nanocomposite thin films, (002) planes were determined as the most basic peak, and it was determined that the intensity of this peak, changed depending on the RF power of polymer thin films. Optical properties of nanocomposite thin films such as transmittance, absorbance and optical band gap were determined by UV–Vis spectroscopy. Optical band gap for PTNZO nanocomposites were 2.72 eV, 2.34 eV, and 2.45 eV, respectively, with increasing RF power. For NZO thin films, this value is 3.12 eV. The optical band gaps calculated from the absorption and transmittance spectra obtained using UV–visible spectroscopy had a good compatibility with those of the optical band spectra calculated from the PL spectra. The tetragonal wurtzite structure of the NZO thin films was examined by SEM analysis. The grain size of NZO nanostructure was found to be approximately 59 nm. [ABSTRACT FROM AUTHOR]

Potentialities of the method of bilayer thin-film electrolyte electrophoretic deposition onto cathodic substrate are analyzed. Ce0.8Sm0.2O1.9-δ (SDC) nanopowder and BaCe0.89Gd0.1Cu0.01O3-δ BCGCuO) micropowder are prepared by the methods of laser evaporation-condensation and pyrolysis, respectively. The effect of ultrasonic treatment on the SDC and BCGCuO particle distribution in suspensions and their electrokinetic properties are studied. The using of the ultrasonic treatment combined with centrifugation allowed obtaining an aggregative-stable suspension of the BaCe0.89Gd0.1Cu0.01O3-δ micron particles in the isopropanol-acetylacetone mixed medium (70/30 v/v) that is characterized by high zeta potential. Ce0.8Sm0.2O1.9-δ and BaCe0.89Gd0.1Cu0.01O3-δ thin films are obtained at the La2NiO4 +δ cathode substrate using electrophoretic deposition; microstructure and electric properties of the prepared thin-film structures are studied. The conductivity and electric properties of the bilayer electrolyte were found to be determined by the Ce0.8Sm0.2O1.9-δ film properties. Despite the sintering high temperature, the grain structure of the BaCe0.89Gd0.1Cu0.01O3-δ film is underdeveloped; this is determined by the micron powder properties. [ABSTRACT FROM AUTHOR]

Bi(0001) films with thicknesses up to several bilayers (BLs) are grown on Se-terminated Bi 2 Se 3 (0001) surfaces, and low energy electron diffraction (LEED), low energy ion scattering (LEIS) and atomic force microscopy (AFM) are used to investigate the surface composition, topography and atomic structure. For a single deposited Bi BL, the lattice constant matches that of the substrate and the Bi atoms adjacent to the uppermost Se atoms are located at fcc-like sites. When a 2nd Bi bilayer is deposited, it is incommensurate with the substrate. As the thickness of the deposited Bi film increases further, the lattice parameter evolves to that of bulk Bi(0001). After annealing a multiple BL film at 120 °C, the first commensurate Bi BL remains intact, but the additional BLs aggregate to form thicker islands of Bi. These results show that a single Bi BL on Bi 2 Se 3 is a particularly stable structure. After annealing to 490 °C, all of the excess Bi desorbs and the Se-terminated Bi 2 Se 3 surface is restored. [ABSTRACT FROM AUTHOR]

UV-Vis spectrometry and quartz crystal microbalance were used to measure the growth of these films as a function of the number of bilayers deposited, while scanning electron microscopy and transmission electron microscopy were used to visualize the morphology of the thin film coatings on the cotton fabric. Nanocomposites formed of cationic starch (CS) and clay introduced fire protection properties into the pure cotton fabric by layer-by-layer (LbL) technique. The optical properties and mass of the films were precisely controlled by the number of bilayers. In this case, CS and clay multilayer thin films were used to increase the thermal stability of the fabrics and improve the anti-flammable properties through the formation of a ceramic char layer and thermally stable carbonaceous structure at a high temperature. This study demonstrates the ability of the LbL technique to produce anti-flammable starch-clay nanocomposite thin films. Cone calorimetry showed the lower total heat release and heat release capacity of the LbL-coated fabric. The LbL-coated cotton samples exhibited a reduced afterglow time in vertical flame tests. An increased amount of residue indicates that the LbL technique is a simple method which can be used to produce eco-friendly flame retardant thin film coatings. [ABSTRACT FROM AUTHOR]

Half-integer conductance, the signature of Majorana edge modes, was recently observed in a thin-film magnetic topological insulator/superconductor bilayer. This letter analyzes a scheme for gate control of Majorana zero modes in such systems. Gating the top surface of the thin-film magnetic topological insulator controls the topological phase in the region underneath the gate. The voltage of the transition depends on the gate width, and narrower gates require larger voltages. Relatively long gates are required, on the order of 2 μm, to prevent hybridization of the end modes and to allow the creation of Majorana zero modes at low gate voltages. Applying voltage to T-shaped and I-shaped gates localizes the Majorana zero modes at their ends. This scheme may provide a facile method for implementing quantum gates for topological quantum computing. [ABSTRACT FROM AUTHOR]

Bilayer films of Nd0.7Sr0.3MnO3/Nd0.8Na0.2 MnO3 were grown on 001-orientated LaAlO3 substrate by using RF magnetron sputtering. The thickness of the Nd0.8Na0.2MnO3 (NNMO) film was kept fixed at 120 nm while that of the Nd0.7Sr0.3MnO3 (NSMO) film was varied from 12 to 100 nm. X-ray diffraction patterns confirm the growth of films along the (001) direction, and the out-of-plane lattice constant of the NSMO film decreases with an increase in film thickness. The bilayer films are found to undergo out-of-plane tensile strain, and the lattice strain is found to decrease with an increase in film thickness. The ferromagnetic transition temperature is found to increase with an increase in the NSMO film thickness. M-H loops recorded at 50 K show a systematic increase in saturation magnetisation with an increase in film thickness. Metal-insulator transition has been observed for the film thickness of 30 nm and above, and the transition temperature is found to increase with an increase in film thickness. The electrical resistivity data in the metallic region were explained based on electron-electron and electron-magnon scattering mechanism by including a weak localisation effect at low temperature. The electrical resistivity data in the insulating region follow the Mott-variable range hopping model. [ABSTRACT FROM AUTHOR]

We measure the inverse spin Hall effect of Cu1-xIrx thin films on yttrium iron garnet over a wide range of Ir concentrations (0.05 ⩽ x ⩽ 0.7). Spin currents are triggered through the spin Seebeck effect, either by a continuous (dc) temperature gradient or by ultrafast optical heating of the metal layer. The spin Hall current is detected by electrical contacts or measurement of the emitted terahertz radiation. With both approaches, we reveal the same Ir concentration dependence that follows a novel complex, nonmonotonous behavior as compared to previous studies. For small Ir concentrations a signal minimum is observed, whereas a pronounced maximum appears near the equiatomic composition. We identify this behavior as originating from the interplay of different spin Hall mechanisms as well as a concentration-dependent variation of the integrated spin current density in Cu1-xIrx. The coinciding results obtained for dc and ultrafast stimuli provide further support that the spin Seebeck effect extends to terahertz frequencies, thus enabling a transfer of established spintronic measurement schemes into the terahertz regime. Our findings also show that the studied material allows for efficient spin-to-charge conversion even on ultrafast time scales. [ABSTRACT FROM AUTHOR]

In this work, we present a procedure to modify the exchange bias (EB) properties of antiferromagnetic Mn/ferromagnetic NiFe bilayers by in-situ low energy Ar + bombardment of the Mn layer during sample deposition. We present structural and magnetic results for unassisted and Ar + assisted Mn/NiFe bilayers. X-ray diffraction, transmission electron microscopy and electron diffraction results establish different preferred Mn orientation directions between the two samples as a result of the Ar + bombardment process. Hysteresis loops taken over several temperatures reveal that samples assisted with Ar + ions during the Mn layer deposition had suppressed EB properties at low temperature as compared to samples grown without Ar + assistance. [ABSTRACT FROM AUTHOR]

The magnetic profile of the Si(100)/NiO(35 nm)/NiFe(10 nm)/Ta(1 nm) sample has been obtained by X-ray absorption spectroscopy (XAS) and the X-ray magnetic circular dichroism (XMCD). Two experimental procedures were used. In the procedure 1, the magnetic depth profile has been determines using samples deposited with different NiFe thicknesses, Si(100)/NiO(35 nm)/NiFe(t)/Ta(1 nm), t = 1 , 3 , 5 , 7 , 10 nm . In procedure 2, the sample (NiFe=10 nm), was thinned by several in situ sputtering cycles with Ar+ ions, followed by XAS and XMCD analysis. In both procedures, the calculated magnetic moments values tend to decrease close to interface with the NiO antiferromagnetic (AF) layer, however, this decreasement is more evidenced in the sputtered sample. There is no charge transfer between Ni and Fe in the inner part of the NiFe layer, a reduction of the m orb / m spin eff has been found at the NiFe/NiO interface. Procedure 1 emerged as the most indicated to analyse the interface region. [ABSTRACT FROM AUTHOR]

Process of magnetization and magnetoresistance have been studied in nanoisland bilayer systems of FeNi-Co. Hysteresis loops show characteristic features (steps) most clearly observed in certain orientations of the sample in a magnetic field. To explain these features the concept of flat magnetic exchange spring has been introduced for nanoisland bilayers. It has been proposed that additional magnetoresistance can be the result of spin-dependent scattering of electrons in the area of flat magnetic exchange spring. Magnetoresistance studies of bilayer systems has shown that additional magnetoresistance occurs at the same magnetic fields as steps on hysteresis loops. [ABSTRACT FROM AUTHOR]

The theoretical studies on acoustoelectrical (AE) sensitivity in SAW gas sensors with a single and bi-layer structures were presented. The analysis was based on normalized parameter ξ = σ s /v 0 C s (where: σ s − is the film’s electrical surface conductivity, v 0 –SAW velocity, C s − sum of the substrate’s and environment’s electrical permittivities) which determines the value of AE sensitivity and elemental theory of SAW interactions with semiconductor sensor thin film nanostructures. The electrical surface conductivities in the bi-layer structure are correlated by the σ s1 = x σ s2 dependence, where the x parameter determines how much the electrical conductivity of the first film is bigger than the second one. The investigations revealed that for single and bi-layer sensor structures the maximum value of AE sensitivity was obtained for parametr ξ max = ∼0.6. For bi-layer structures this sensitivity is lower. However we also found the positions of the maximum values in a function of x design parameter dependently on different values of normalized conductivity of the second film. [ABSTRACT FROM AUTHOR]

Spontaneous exchange bias (EB) is reported for as deposited Si/Pt( t Pt )/Ni 45 Mn 55 ( t AFM /Co( t FM )/Pt(30 Å) thin film system without requiring any post annealing, deposition with field or field cooling procedures. Magnetic properties of this system were investigated with respect to thicknesses of buffer Pt layer ( t Pt ), antiferromagnetic NiMn layer ( t AFM ) and ferromagnetic Co layer ( t FM ). Exchange coupling between NiMn and Co layers enhanced considerably by increasing t Pt . In order to observe a spontaneous EB in the system, Pt buffer layer must be thicker than a certain thickness, and NiMn layer must be grown directly on the buffer layer. On the other hand, significant increments in the coercive fields ( H C ) were reported for thinner Pt buffer layers. The thickness ranges for Co and NiMn layers were also determined to obtain spontaneous EB. This spontaneous EB is discussed to be a result of NiMn (111) texture which is induced by Pt buffer layer. Greater EB fields ( H EB ) are measured for the samples in the negative field direction by the effect of annealing and field cooling (from 400 K to 300 K at 2 kOe). [ABSTRACT FROM AUTHOR]

A lift-off process using a bi-layer resist consisting of an image reversal resist on top and a lift-off resist at the bottom was used to structure Ti–Pt thin films. DC magnetron sputtered metal films patterned by this process show ultra smooth edges, ideal for applications such as interdigitated electrodes in resistive gas sensors including thin-film based sensitive coatings with thicknesses below 100 nm. Profiles of processed structures were analyzed by scanning electron microscopy and surface profilometer. The thickness profile and structure width were controlled by using different resist thicknesses and undercut lengths. Results were compared with iterative simulations by a geometric shadowing model, predicting undersputtering length and profile structure of the experimentally manufactured samples in good agreement. Target-to-substrate distance variation was found to have only a minor influence on the sputtering result. [ABSTRACT FROM AUTHOR]

We report on highly efficient organic phototransistors (OPTs) based on thin-film/single-crystal planar bilayer junctions between 5,6,11,12-tetraphenyltetracene (rubrene) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM). The OPTs show good field-effect characteristics in the dark, with high holemobility (4-5cm²V-1 s-1), low-contact resistance (20 kΩcm), and low-operating voltage (≤5V). Excellent sensing capabilities allow for light detection in the 400-750 nm range, with photocurrent/ dark current ratio as high as 4×104, responsivity on the order of 20AW-1 at 27 μWcm-2, and an external quantum efficiency of 52 000%. Photocurrent generation is attributed to enhanced electron and hole transfer at the interface between rubrene and PC61BM, and fast response times are observed as a consequence of the high-mobility of the interfaces. The optoelectronic properties exhibited in these OPTs outperform those typically provided by a-Si based devices, enabling future applications where multifunctionality in a single-device is sought. [ABSTRACT FROM AUTHOR]

In this paper, electrical bistability of ITO/copper phthalocyanine (CuPc)/fullerene (C 60 )/Al structure for organic memory applications was studied. X-ray diffraction studies on the deposited film showed crystallinity with a major peak (100) for CuPc. It was seen that the stored conductivity state was rather stable in ITO/CuPc/C 60 /Al for use in organic memory cells. ON/OFF resistance ratio of around 10 5 was obtained for the CuPc/C 60 device. Electrical bistability of this CuPc/C 60 bilayer device was explained on the basis of filling of the traps and double injection. [ABSTRACT FROM AUTHOR]

Radio frequency magnetron sputtering was adopted to deposit an Al1−x−ySixAgy/Al bilayer thin film anode in this study. The effects of Ag doping and the vacuum annealing on the charge-discharge characteristics of the prepared binary and ternary alloys were discussed. Al-Si based intermetallic alloys are considered as attractive anode materials for lithium ion batteries due to their ultrahigh theoretical capacities. It was observed that Ag doping significantly improved the electrical conductivity and affected the cycling performance. The charge-discharge characteristics of anodes were investigated both at room temperature and 55°C. The relationship between cycling performances and the electrochemical characteristics of the Al1−x−ySixAgy/Al bilayer thin film anodes was also investigated via cyclic voltammetry. The change resulting from annealing in elemental distribution around the interlayer was carefully investigated by TEM to figure out the difference among the cycling performance of specimens. [ABSTRACT FROM AUTHOR]

Adhesion of thin films to hydrophobic elastomeric substrates is of particular interest in the area of flexible electronics and nano-sensor technology. Here, nanometer-thick Au films were deposited directly onto hydrophobic RTV 655 substrates by means of sputtering, thermal evaporation, and electroless techniques without an adhesion-promoting layer. The bilayer system was exposed to repeat thermal cycling and changes to the surface morphology of the thin film were monitored electrically and optically. Buckle formation in the as-deposited film was attributed to stress in the film and substrate stiffness rather than thermal coefficient mismatch between films. The Au-RTV 655 interface was water tight and maintained a strong adhesion despite repeated thermal cycles. Sputtered and thermally evaporated carbon-coated RTV 655 substrates were also studied in parallel for comparison. Periodic arrays of buckles formed in pre-strained RTV 655 samples showed reproducibility in their optical properties demonstrating good adhesion between the two layers without an interfacial layer. [ABSTRACT FROM AUTHOR]

The Fe 2 O 3 , Au:Fe 2 O 3 , TiO 2 /Fe 2 O 3 and TiO 2 /Au:Fe 2 O 3 thin films are successfully prepared by the spray pyrolysis technique at an optimised substrate temperature of 400 °C and 470 °C, respectively onto amorphous and F:SnO 2 coated glass substrates. The effect of TiO 2 layer onto photoelectrochemical (PEC), structural, optical and morphological properties of Fe 2 O 3 , Au:Fe 2 O 3 , TiO 2 /Fe 2 O 3 and TiO 2 /Au:Fe 2 O 3 thin films is studied. The PEC characterization shows that, maximum values of short circuit current ( I sc ) and open circuit voltage ( V oc ) are ( I sc = 185 μA and V oc = 450 mV) are at 38 nm thickness of TiO 2 . Deposited films are polycrystalline with a rhombohedral and anatase crystal structure having (1 0 4) preferred orientation. SEM and AFM images show deposited thin films are compact and uniform with seed like grains. The photocatalytic activities of the large surface area (64 cm 2 ) TiO 2 /Au:Fe 2 O 3 thin film photocatalysts were evaluated by photoelectrocatalytic degradation of industrial wastewater under sunlight light irradiation. The results show that the TiO 2 /Au:Fe 2 O 3 thin film photocatalyst exhibited about 87% and 94% degradation of pollutant in sugarcane and textile industrial wastewater, respectively. The significant reduction in COD and BOD values from 95 mg/L to 13 mg/L and 75 mg/L to 11 mg/L, respectively was also observed. [ABSTRACT FROM AUTHOR]

In this work, TiO 2 –MoO 3 films were easily prepared by dip-coating technique and metallo-organic decomposition process (MOD). Raman analyses indicate the formation of TiO 2 in anatase phase and orthorhombic phase of α-MoO 3 . It was observed that the Raman bands intensities attributed to TiO 2 and MoO 3 oxides were dependent on the number of decomposition–deposition cycles (DDC). The different number of DDC generates films with different thicknesses and the Raman signal was sensitive to this variation. Raman analyses provided qualitative information about the bilayer structure of the bi-component TiO 2 –MoO 3 films, which was confirmed by scanning electron microscopy. In this direction, the dip-coating technique and MOD process can be an efficient strategy to facile preparation of many samples to be used in applications. [ABSTRACT FROM AUTHOR]

In the present work, bi-layer thin films of Sb/SnO 2 were produced on unheated glass substrates using ion beam sputtering (IBS) technique without post annealing treatment. The thickness of Sb layers was varied from 2 to 10 nm and the Sb layers were deposited on SnO 2 layers having thicknesses of 40 nm to 115 nm. The effect of thickness was studied on the morphological, electrical and optical properties. The Sb/SnO 2 bi-layer resulted in lowering the electrical resistivity as well as reducing the optical transmittance. However, the optical and electrical properties of the bi-layer films were mainly influenced by the thickness of Sb layers due to progressive transfer in structures from aggregate to continuous films. The bi-layer films show the electrical resistivity of 1.4 × 10 − 3 Ω cm and an optical transmittance of 26% for Sb film having 10 nm thickness. [ABSTRACT FROM AUTHOR]

Chromium/silicon bilayers are deposited by sequential electron beam evaporation on quartz substrates. The bilayers consisting of Cr and Si layers of 50 and 400 nm thicknesses, respectively, are subjected to post-deposition annealing at temperatures from 200 to 700 °C. The thermal annealing results in the interdiffusion between Cr and Si, as evidenced by cross-section scanning electron micrographs and the line profiles obtained from energy-dispersive X-ray spectroscopy. It is inferred from the compositional line profiles that the films are a combination of silicon-rich oxide, chromium oxide and unreacted Cr up to 500 °C. Chromium disilicide forms at temperatures greater than 500 °C with decrease in chromium oxide content. The refractive index value and extinction coefficient values are 2.1 and 0.12 in the as-deposited case which increase to 3.5 and 0.24 at 400 °C. These values decrease to 2.1 and 0.12 at 500 °C. At the same temperatures, the band gap values are 2.21, 2.40 and 2.28, respectively. Thus, the refractive index, absorption coefficient and the optical band gap of the films peak at an annealing temperature of 400 °C and decrease thereafter. Significantly, this is accompanied by increase in Urbach energy which is an indication of increase in disorder in the system. There is decrease in Urbach energy as well as the optical constants at temperatures >400 °C. [ABSTRACT FROM AUTHOR]

We present a study of the influence of the iodine/solvent annealing temperature on the properties of piezoresistive bilayer films with layers of α-(BEDT-TTF)2I3 [BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene]. The formation of the conductive layers was tested by XRD, direct current (dc) conductivity measurements, and SEM, and the electromechanical properties have also been studied. We demonstrate that it is possible to form bilayer (BL) films with an invariant gauge factor of ca. 10 but with the temperature dependence of the resistance variable from metallic to semiconductor-like by control of the annealing temperature. This control even permits the preparation of a BL film with temperature-independent resistance. [ABSTRACT FROM AUTHOR]

We present a study of the influence of the iodine/solvent annealing temperature on the properties of piezoresistive bilayer films with layers of α-(BEDT-TTF)2I3 [BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene]. The formation of the conductive layers was tested by XRD, direct current (dc) conductivity measurements, and SEM, and the electromechanical properties have also been studied. We demonstrate that it is possible to form bilayer (BL) films with an invariant gauge factor of ca. 10 but with the temperature dependence of the resistance variable from metallic to semiconductor-like by control of the annealing temperature. This control even permits the preparation of a BL film with temperature-independent resistance. [ABSTRACT FROM AUTHOR]

Abstract: We investigate the improvement of p–i–n type thin-film silicon (Si) solar cells by employing a hydrogenated n-type amorphous Si (n-a-Si:H)-based bilayer. The initial conversion efficiency (η) of a-Si:H single-junction solar cells is improved from 9.2 to 10.0%. The developed n-a-Si:H-based bilayer is also suitable for a-Si:H/hydgrogenated microcrystalline Si (μc-Si:H) double-junction solar cells, and thus initial η is improved from 10.4 to 10.8%. With a further optimization, initial η of 11.3% and stabilized η of 10.1% are achieved. Since the n-a-Si:H-based bilayer is easily formed using a conventional process, it can be a promising option for cost-effective mass production of large-area thin-film Si solar modules. [Copyright &y& Elsevier]

Abstract: The optical properties of bilayer thin films of Bi/As2S3 with various thicknesses which were prepared from Bi and As2S3 by thermal evaporation technique under high vacuum were characterized by Fourier Transformed Infrared Spectroscopy, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The prepared bilayer films of 905nm, 910nm and 915nm thickness have As2S3 as bottom layer (900nm) and Bi as top layer (5,10,15nm). X-ray diffraction studies confirm the amorphous nature of the prepared films. The optical properties show a strong dependence on the film thickness. It was found that the optical band gap increases with film thickness. The obtained lower values of Urbach energy indicate that as thickness increases, more ordered films can be produced. The reduction in disorder in bonding network is amply supported by the way of increase in band gap, increase in Tauc parameter (B 1/2) and reduction in Urbach energy from the analysis of transmittance spectra. The change in XPS core level spectra and Raman spectra also shows the changes due to thickness. [Copyright &y& Elsevier]

We present an exchange bias (EB) effect of variable size in La0.67Sr0.33MnO3-δ single and La0.67Sr0.33MnO3-δ/SrTiO3 (LSMO/STO) bilayers grown on STO substrates. Samples have been prepared by pulsed laser deposition (PLD) and high-pressure sputter deposition (HSD) in oxygen atmosphere at different oxygen pressures. Increased out-of-plane lattice parameters of the LSMO layers and reduced Curie temperatures indicate oxygen deficiencies in the samples grown at lower oxygen pressures. We found an increase of the EB and the coercive fields with decreasing oxygen pressure, whereas the growth at high pressures does not lead to an EB effect. The depth-sensitive method of polarized neutron reflectometry (PNR) reveals a region with drastically reduced, maybe even completely vanishing net magnetization in the LSMO layer at the interface to STO in the exchange-biased samples, but not in the non-exchanged-biased one. It is suggested that an antiferromagnetic structure is formed in this part of the LSMO thin film, which causes the EB effect in this system. An explanation based on the strain-doping phase diagram of LSMO is provided. Thus our findings open a route for tuning the EB effect by changing the oxygen vacancy concentrations. [ABSTRACT FROM AUTHOR]

Highlights: [•] Abnormal switching properties of a bilayer film are studied. [•] Serious lag phenomenon of the hysteresis loop of the bilayer film occurs. [•] There is a critical point for switching time and remanent polarization. [•] The system exists a competed mechanism. [ABSTRACT FROM AUTHOR]

Single layered aluminium doped tin oxide (ATO), fluorine doped zinc oxide (FZO) and bi-layered ATO/FZO thin films were deposited onto preheated glass substrates (T = 340 ± 5 °C) using a low-cost and simplified spray pyrolysis technique. The structural, optical, electrical and surface morphological properties of the bi-layered ATO/FZO thin films were studied and compared with that of the single layered films. The average optical transmittance of the bi-layer film in the visible range was found to be around 80 %. The bi-layered ATO/FZO films possessed both better transmittance in the visible range and sharp absorption edge, the unique desirable features of ATO and FZO films, respectively. The optical band gap (E) value of the bi-layer coating (3.22 eV) was found to lie between the E values of single layered ATO (3.71 eV) and FZO (3.20 eV) films. Sheet resistance values of ATO and FZO single layer films were 3.47 and 11.2 kΩ/sq., respectively. The bi-layered ATO/FZO thin films exhibited a sheet resistance of 4.42 kΩ/sq. which was very much close to that of ATO films and three times less than that of FZO film. The AFM images showed the good packing density and homogeneity of the surface of the bi-layer films. The annealing studies clearly showed that the ATO over layer remarkably improved the thermal stability of the bi-layered film. [ABSTRACT FROM AUTHOR]

Abstract: Morphology control of ZnO bilayer structure films has been obtained via low-temperature hydrothermal process without any surfactant-assistance. ZnO bilayer structures including nanoflower layer on nanorod array structure, nanodendrite layer over nanorod array structure, and double nanorods layers structures were successfully fabricated by controlling the ammonia concentration in the initial hydrothermal solution and the immersing ways. The shape evolution of bilayer structure consisting of nanodendrite layer on the top and nanorod array at the bottom was elucidated by growing–renucleating mechanism. The higher ammonia concentration in the initial hydrothermal solution promotes the secondary nucleation and growth on the surface defects of backbones, resulting in the formation of needle-like nanorods in ZnO nanodendrite–nanorod structure. The ZnO film with nanodendrite–nanorod structure has better optical properties and lesser defects compared to that of nanoflower–nanorod structures. [Copyright &y& Elsevier]

Tetraphenylethylene (TPE) derivatives have been proved to be typical aggregation-induced emission (AIE) luminogens when they were aggregated in the free three-dimensional space. In order to reveal the effect of the dimensional degree on AIE property of TPEs, we utilized tetra(4-hydroxyphenyl)ethylene (TPE-4OH) and 1,4-benzenediamine diazonium salt (BD) to fabricate the ultra-thin films (TPE-4OH/BD LBL SA film) through layer-by-layer self-assembled technique. The interaction between TPE-4OH and BD in the films was converted from electrostatic force and hydrogen-bond to covalent bonds through photodecomposition of diazonium groups under UV irradiation. Fluorescence emission spectroscopy, UV-Vis absorption spectroscopy and atomic force microscope were carried out to evaluate the relationship between bilayer number and photoluminescence of the TPE-based self-assembled films. The experimental results showed that the TPE-based film with three bilayers only displayed AIE character, whereas the fluorescence of the film became randomly changed if the bilayer number was above three. It is supposed that the fluorescence property of the TPE-4OH/BD LBL SA film with limited molecular length in z-axis and infinite aggregation space in x- and y-axis is dominated by two competitive effects, one is the partial restriction of intramolecular rotation through short intermolecular interactions in cross-linked structure of TPE-4OH/BD, and the other is deactivation of its excited state through unrestricted intramolecular rotations or π-π interactions. [ABSTRACT FROM AUTHOR]

Abstract: The epitaxial La0.7Sr0.3MnO3/BaTiO3 bilayers were deposited on (001), (110) and (111) LaAlO3 substrates by pulsed laser deposition technique. All of the bilayers presented coherent ferromagnetic and ferroelectric properties. Furthermore, a strong magnetoelectric (ME) effect at room temperature was approved, which strongly correlated to the film orientation. The ME voltage coefficients for (001), (110) and (111) oriented bilayers were around 140mV/cmOe, 105mV/cmOe, and 120mV/cmOe, respectively. These values were at least one order of magnitude higher than previous reported results, which mainly related to the good interface quality of La0.7Sr0.3MnO3/BaTiO3 bilayers and the small dielectric constant of BaTiO3 film. [Copyright &y& Elsevier]

Scanning tunneling microscopy andlocal conductance mapping showspin-state coexistence in bilayer films of Fe[(H2Bpz2)2bpy] on Au(111) that is independent of temperaturebetween 131 and 300 K. This modification of bulk behavior is attributedin part to the unique packing constraints of the bilayer film thatpromote deviations from bulk behavior. The local density of statesmeasured for different spin states shows that high-spin moleculeshave a smaller transport gap than low-spin molecules and are in agreementwith density functional theory calculations. [ABSTRACT FROM AUTHOR]

Exchange coupling has been investigated in FeMn/Gd bilayers where the Curie temperature ( T C ) of Gd is much lower than the Néel temperature ( T N ) of FeMn. The coercivity ( H C ) exhibits unusual temperature dependence. As temperature increases, it decreases at first, then goes up to the maximum and keeps it in medium temperature range, finally drops rapidly and disappears at T N . The exchange bias field ( H E ) is negative initially and its magnitude decreases monotonically with increasing temperature, then it turns to be positive, finally disappears at high temperatures. The anomalous H C (T) behavior may be ascribed to the non-collinear coupling interaction at the FeMn/Gd interface. The positive H E can be attributed to the antiferromagnetic coupling between the interfacial Gd and FeMn moments. Moreover, the antiferromagnetic ordering adjacent to the FeMn layer may be responsible for inducing the exchange coupling at T C < T < T N . [ABSTRACT FROM AUTHOR]

Bi 4 Ti 3 O 12 /BiFeO 3 (BTO/BFO) heterostructure bilayer film is prepared on fluorine-doped tin oxide conductive glass by a sol–gel process. The X-ray diffraction result shows that no additional phase can be found besides the characteristic diffraction peaks of BTO and BFO. Piezoelectric force microscopy measurement confirms the complete domain switching and local ferroelectric nature. The open circuit voltage and short circuit current density of the bilayer film are measured to be about 0.38 V and −56.24 µA cm −2 , respectively, higher than those of the BTO. The BTO/BFO film exhibits repeatable and stable instantaneous response of photocurrent. A theoretical band diagram model combining p – n heterostructure with ferroelectric polarization is constructed to describe the mechanism of photovoltaic enhancement of the film. [ABSTRACT FROM AUTHOR]

Rutile-phased TiO 2 thin films consist of single layer of nanorod structure and bilayer of nanorod and nanoflower structure with thickness of 2–10 μm were synthesized on FTO glass substrate and its Seebeck coefficient and electrical conductivity were measured in order to clarify the influence of layer's structure on its thermoelectric power factor for self-powered smart window material application. The Seebeck coefficient and electrical conductivity of TiO 2 thin films were found to be dependent on the type of layer's structure, and to be independent on the thickness of the layer, which is likely due to the elimination of phonon system contribution and its anisotropic dependency. The bilayer TiO 2 thin film is found to possess the highest power factor of 79.7 μW/mK2 at 390 K, which is almost three times larger compared with a reported value for oxide material on glass substrate. These show a promising possibility to apply TiO 2 thin film as thermoelectric harvester film fabricated on glass window. Unlabelled Image • TiO 2 layer's nanostructure influences its thermoelectric parameters. • Thermoelectric power factor is likely to be independent on the thickness of layer in micrometer size. • Anisotropic characteristics in rutile-phase TiO 2 is likely to influence the thermoelectric power factor. • Phonon system contribution part in Seebeck coefficient is likely observed at room temperature. • There is possibility to apply nanostructured TiO 2 thin film as thermoelectric window film. [ABSTRACT FROM AUTHOR]

The bilayered structure of hard thin film on soft substrate can lose stability and form specific patterns, such as wrinkles or creases, on the surface, induced by external stimuli. For bilayer hydrogels, the surface morphology caused by the instability is usually controlled by the solvent-induced swelling/shrinking and mechanical force. Here, two important issues on the instability of bilayer hydrogels, which were not considered in the previous studies, are focused on in this study. First, the upper layer of a hydrogel is not necessarily too thin. Thus we investigated how the thickness of the upper layer can affect the surface morphology of bilayer hydrogels under compression through both finite element (FE) simulation and theoretical analysis. Second, a hydrogel can absorb water molecules before the mechanical compression. The effect of the pre-absorption of water before the mechanical compression was studied through FE simulations and theoretical analysis. Our results show that when the thickness of the upper layer is very large, surface wrinkles can exist without transforming into period doublings. The pre-absorption of the water can result in folds or unexpected hierarchical wrinkles, which can be realized in experiments through further efforts. [ABSTRACT FROM AUTHOR]