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Herein, the pressure dependence of the electrical resistance Rof superconducting 4d and 5d transition metal compounds, CaRh2and CaIr2, with superconducting transition temperatures, Tc’s, as high as 6.09 and 6.04 K at ambient pressure, respectively, is investigated to depict their Tc–pressure (p) phase diagrams. The superconductivity of these samples is investigated based on plots of R vstemperature (T) over a wide pressure range. It is demonstrated that the Tcof both compounds decreases slowly as pressure increases but saturates in a high pressure range. This behavior is similar to that of SrIr2reported previously, suggesting that it may be a unique behavior of the 4d and 5d transition metal compounds investigated. The crystal structures of CaRh2and CaIr2are determined based on powder X-ray diffraction patterns generated viasynchrotron radiation at high pressures, and no structural phase transitions are observed up to ∼20 GPa. The magnetic field dependence of R–Tplots recorded at 12.2 and 7.98 GPa for CaRh2and CaIr2, respectively, is analyzed using three pairing models. Consequently, the superconductivity of CaRh2and CaIr2could not be explained merely based on s-wave dirty limit and s-wave clean limit models but rather the p-wave polar model. We fully analyzed the magnetic behavior of the superconducting phases of CaRh2and CaIr2at ambient and high pressures using three different methods: the Werthamer–Helfand–Hohenberg/Maki, empirical, and Ginzburg–Landau models. This report provides a systematic study pertaining to the pressure dependence of superconductivity in binary-element compounds comprising alkali-earth and 4d or 5d transition metal atoms.

Electronic devices relying on the combination of different conjugated organic materials are considerably appealing for their potential use in many applications such as photovoltaics, light emission, and digital/analog circuitry. In this study, the electrical response of field-effect transistors achieved through the evaporation of picene and PDIF-CN2molecules, two well-known organic semiconductors with remarkable charge transport properties, was investigated. With the main goal to get a balanced ambipolar response, various device configurations bearing double-layer, triple-layer, and codeposited active channels were analyzed. The most suitable choices for the layer deposition processes, the related characteristic parameters, and the electrode position were identified to this purpose. In this way, ambipolar organic field-effect transistors exhibiting balanced mobility values exceeding 0.1 cm2V–1s–1for both electrons and holes were obtained. These experimental results highlight also how the combination between picene and PDIF-CN2layers allows tuning the threshold voltages of the p-type response. Scanning Kelvin probe microscopy (SKPM) images acquired on picene/PDIF-CN2heterojunctions suggest the presence of an interface dipole between the two organic layers. This feature is related to the partial accumulation of space charge at the interface being enhanced when the electrons are depleted in the underlayer.

Near-field light sources made it possible to go beyond the diffraction limit. Innovative nanophotonics offers potential throughout the field of photonics, including industrial applications such as high-efficiency solar cells. These applications require a novel technique for generating not a nanometer-scale point but a large-area (mm2-m2) near-field light source. Here, we report the first large-area near-field light source that is densely constructed of uniform-size gold nanoparticles (AuNPs) two-dimensionally arrayed with regular interparticle gaps, which eventually has tunable localized surface plasmon resonance (LSPR) bands (600-1100 nm). The light source is attached by means of chemical coating on 1x1-cm2 substrates, but there is no limitation on the size.

We investigated the pressure dependence of electric transport in a superconducting sample, Ba0.77Na0.23Ti2Sb2O, to complete the phase diagram of superconducting transition temperature (Tc) against pressure (p). This superconducting sample exhibits a Tcvalue of 5.8 K at ambient pressure. Here, the superconductivity of the recently reported sample was investigated over a wide pressure range. The Tcvalue monotonously decreased with pressure below 8 GPa. Interestingly, the Tcvalue rapidly increased above 8 GPa and slowly declined with pressure above 11 GPa. Thus, a new superconducting phase was discovered above ∼9 GPa. The crystal structure of Ba0.77Na0.23Ti2Sb2O was also elucidated at 0–22.0 GPa with synchrotron X-ray powder diffraction. Consequently, an evident relation between the crystal structure and the superconductivity was revealed, namely, a clear structural phase transition was observed at 8–11 GPa, where the Tcvalue rapidly increased against pressure. This study provides detailed information on the superconductivity of Ba0.77Na0.23Ti2Sb2O under pressure, which will lead to a comprehensive understanding of pressure-driven superconductivity.

A new superconducting sample, Ba1[?]x Cs x Ti2Sb2O, was prepared and characterized in a wide pressure range. The maximum value of superconducting transition temperature, T c, of Ba1[?]x Cs x Ti2Sb2O was 4.4 K for x = 0.25 at ambient pressure. The crystal structure was determined to be tetragonal [space group of P4/mmm (No. 123)]. The charge density wave/spin density wave transition was observed at 44 K for Ba1[?]x Cs x Ti2Sb2O (nominal x = 0.25) at ambient pressure, but the transition was suppressed by applying pressure. The pressure dependent X-ray diffraction showed no structural phase transition up to 23.4 GPa, but very interesting T c-pressure (p) behavior was observed, i.e. the T c decreases with an increase in pressure up to 4.0 GPa, but it increased above 4.0 GPa, suggestive of non-BCS type behavior. Thus, the systematic study on new pnictide superconductor, Ba1[?]x Cs x Ti2Sb2O, was achieved, and the fascinating behavior of superconductivity against pressure was discovered.

Two-dimensional arrays of gold nanoparticles (AuNPs) as localized surface plasmon-resonant (LSPR) optics on a transparent conductive layer of indium-tin-oxide (ITO) were successfully fabricated. The typical surface coverage of the 10 nm sized AuNPs is over 87% for on ITO film roughness of ±0.2 nm. The LSPR wavelength is tunable in the range of 622-905 nm. By adjusting the LSPR wavelength to 905 nm at peak, two-photon photochromic reaction of diarylethene derivative in solution phase was demonstrated with irradiation by an incoherent near-infrared light in the range of 0.017-0.033 W/cm2instead of a laser, thanks to the AuNP two-dimensional array.

Two-dimensional arrays of gold nanoparticles (AuNPs) as localized surface plasmon-resonant (LSPR) optics on a transparent conductive layer of indium-tin-oxide (ITO) were successfully fabricated. The typical surface coverage of the 10 nm sized AuNPs is over 87% for on ITO film roughness of +-0.2 nm. The LSPR wavelength is tunable in the range of 622-905 nm. By adjusting the LSPR wavelength to 905 nm at peak, two-photon photochromic reaction of diarylethene derivative in solution phase was demonstrated with irradiation by an incoherent near-infrared light in the range of 0.017-0.033 W/cm2 instead of a laser, thanks to the AuNP two-dimensional array.

Near-field light sources made it possible to go beyond the diffraction limit. Innovative nanophotonics offers potential throughout the field of photonics, including industrial applications such as high-efficiency solar cells. These applications require a novel technique for generating not a nanometer-scale point but a large-area (mm2-m2) near-field light source. Here, we report the first large-area near-field light source that is densely constructed of uniform-size gold nanoparticles (AuNPs) two-dimensionally arrayed with regular interparticle gaps, which eventually has tunable localized surface plasmon resonance (LSPR) bands (600-1100 nm). The light source is attached by means of chemical coating on 1×1-cm2substrates, but there is no limitation on the size.