Superconductivity in higher titanium oxides

Recent renewal of the highest transition temperature in a conventional superconductor of the sulfer hydride attracts much attention to exploring simple compounds with the lighter elements, situated in unconventional conditions. We report the discovery of superconductivity in simple oxides of Ti4O7 and g-Ti3O5 in a thin-film form having deliberately tuned epitaxial structures and off-stoichiometry. These higher titanium oxides join in a class of simple-oxide superconductors, and g-Ti3O5 now holds the highest superconducting transition temperature of 7.1 kelvin among them. The mechanism behind the superconductivity is discussed on the basis of electrical measurements and theoretical predictions. We conclude that superconductivity arises from unstabilized bipolaronic insulating states.Comment: 25 pages, 4 figures in main text, 14 pages, 11 figures in supplemental informatio

Monte-Carlo simulation of localization dynamics of excitons in ZnO and CdZnO quantum well structures

Localization dynamics of excitons was studied for ZnO/MgZnO and CdZnO/MgZnO quantum wells (QW). The experimental photoluminescence (PL) and absorption data were compared with the results of Monte Carlo simulation in which the excitonic hopping was modeled. The temperature-dependent PL linewidth and Stokes shift were found to be in a qualitatively reasonable agreement with the hopping model, with accounting for an additional inhomogeneous broadening for the case of linewidth. The density of localized states used in the simulation for the CdZnO QW was consistent with the absorption spectrum taken at 5 K.Comment: 4 figures, to appear in J. Appl. Phy

Polarization properties of laser-diode-pumped micro-grained Nd:YAG ceramic lasers

Detailed polarization properties have been examined in laser-diode-pumped (LD-pumped) micro-grained ceramic Nd:YAG lasers in different microchip cavity configurations. Stable linearly-polarized single-frequency oscillations, whose polarization direction coincide with that of an LD pump light, were observed in an external cavity scheme. While, in the case of a thin-slice laser scheme with coated reflective ends, elliptically-polarized single-frequency operations took place in the low pump-power regime and dynamic instabilities appeared, featuring self-induced antiphase modulations among counter-rotating circularly-polarized components having slightly different lasing frequencies, with increasing the pump power.Comment: 9 pages, 5 figure

Single crystalline ZnO films grown on lattice-matched ScAlMgO4(0001) substrates

科研費報告書収録論文(課題番号:09355030・基盤研究(A)(2)・H9～H11/研究代表者:宮本, 明/次世代エレクトロニクス材料としての酸化物人口超格子の原子レベル設計と開発

Photoemission study of TiO2/VO2 interfaces

We have measured photoemission spectra of two kinds of TiO$_2$-capped VO$_2$ thin films, namely, that with rutile-type TiO$_2$ (r-TiO$_2$/VO$_2$) and that with amorphous TiO$_2$ (a-TiO$_2$/VO$_2$) capping layers. Below the Metal-insulator transition temperature of the VO$_2$ thin films, $\sim 300$ K, metallic states were not observed for the interfaces with TiO$_2$, in contrast with the interfaces between the band insulator SrTiO$_3$ and the Mott insulator LaTiO$_3$ in spite of the fact that both TiO$_2$ and SrTiO$_3$ are band insulators with $d^0$ electronic configurations and both VO$_2$ and LaTiO$_3$ are Mott insulators with $d^1$ electronic configurations. We discuss possible origins of this difference and suggest the importance of the polarity discontinuity of the interfaces. Stronger incoherent part was observed in r-TiO$_2$/VO$_2$ than in a-TiO$_2$/VO$_2$, suggesting Ti-V atomic diffusion due to the higher deposition temperature for r-TiO$_2$/VO$_2$.Comment: 5 pages, 6 figure

Estimation of Drug-effect in Use of Multi-tracer Autoradioqraphy - Effect of S-Adenosyl-L-Methionoie on Postischemic Brain Injury in Rat -

開始ページ、終了ページ: 冊子体のページ付

Experience in Use of Multi-Labeled Autoradiography by Means of 18F-Fluorodeoxyglucose and 14C-Iodoantipyrine

開始ページ、終了ページ: 冊子体のページ付