[en] Anomalous transport properties of 40-nm-thick single-crystal Bi(111) films grown on Si(111)-7 × 7 substrates is investigated. The magnetoresistance (MR) of the films in perpendicular magnetic field shows a regular positive behavior in the temperature range 2–300K, the MR in parallel field (B_||) displays a series of interesting features. Specifically, we observe a change of the MR (B_||) behavior from positive to negative when the temperature is below 10K. In the range 10–170 K, the MR (B_||) is negative in the investigated field of 9T. When T > 170 K, a positive MR appears in the high field regime. The low temperature MR(B_||) behavior in the parallel field can be understood by the competition between weak localization and weak anti-localization (WAL). Furthermore, our results suggest that the WAL is dominated by the interface carriers

[en] Transport characteristics of single crystal bismuth films on Si(111)-7 × 7 are found to be metallic or insulating at temperatures below or above T_C, respectively. The transition temperature T_C decreases as the film thickness increases. By combining thickness dependence of the films resistivity, we find the insulating behaviour results from the states inside film, while the metallic behaviour originates from the interface states. We show that quantum size effect in a Bi film, such as the semimetal-to-semiconductor transition, is only observable at a temperature higher than T_C. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

[en] We report that fully transparent resistive random access memory (TRRAM) devices based on ITO/TiO₂/ITO sandwich structure, which are prepared by the method of RF magnetron sputtering, exhibit excellent switching stability. In the visible region (400–800 nm in wavelength) the TRRAM device has a transmittance of more than 80%. The fabricated TRRAM device shows a bipolar resistance switching behaviour at low voltage, while the retention test and rewrite cycles of more than 300,000 indicate the enhancement of switching capability. The mechanism of resistance switching is further explained by the forming and rupture processes of the filament in the TiO₂ layer with the help of more oxygen vacancies which are provided by the transparent ITO electrodes

[en] Metal-tip/Pr_0.7Ca_0.3MnO₃/Pt devices possess two types of I — V hysteresis: clockwise vs counter clockwise depending on the tip materials. The criteria for categorization of these two types of devices can be simply based on whether the Gibbs free energy of oxidation for the metal tip is lower or higher than that of PCMO, respectively. While the clockwise hysteresis can be attributed to electric field induced oxidation/reduction, the counter clockwise hysteresis can be explained by oxygen vacancy migration in an electrical field. Alternating-current conductance spectra also reveal distinct hopping barriers between these two categories of devices at high resistive states. (condensed matter: electronic structure, electrical, magnetic, and optical properties)