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Carbon rich Nano-crystalline grain size tantalum carbide (Ta-C) thin films were prepared by non- reactive simultaneously dual magnetron sputtering. The main purpose of the current work was to investigate the influence of deposition method, deposition power, film thickness and annealing temperature on structural, surface morphology and electrical resistivity of TaC thin films. The experimental result shows that the growth rate of film was about 6.7 nm min ^−1 and films are growth like spherical structure. The atomic percentage of elements in the films were very sensitive to the deposition power, which even if the small amount of increases in the deposition power of Ta lead the increase of Ta content. However, a small change in Ta percentage did not result in a change in film structure and surface morphology. Annealing temperature did not cause structural changes in the films, but lead small changes in the grain size (range from 7.0 to 9.1 nm) and surface roughness. Resistivity variation of deposited TaC films on the annealing temperature shows random behavior which may cause by the deposition method. Nevertheless, the resistivity of the film decreases first and then increases when the thickness increases from 79.2 nm to 134 nm. Minimum resistivity of film appears at the thickness of 79.2 nm, about 235.2 μ Ω.cm. In the end, deposited TaC thin films shows good thermal stability and low enough resistivity for gate electrode application.

The transition between onion states and vortex states in exchange-coupled Ni-Fe/Mn-Ir asymmetric ring dots is investigated. A direction of domain wall motion, during the transition from the single-domain state to the vortex state through the onion state, depends on a sweep direction of an external field.

Two new quaternary chalcogenides, Na6CdSb4S10 and Na3CdSbSe4, were successfully synthesized by the high-temperature solid-state reaction in vacuum-sealed silica tubes. Note that Na6CdSb4S10 crystallizes in the C2/c space group, whereas Na3CdSbSe4 crystallizes in the P21/c space group. As seen from their structures, Na6CdSb4S10 exhibits a three-dimensional (3D) framework structure composed by the interconnection of isolated [(Cd/Sb)2Sb2S10] clusters and two different layers formed by the NaSn (n = 4, 6) units; besides, the structure of Na3CdSbSe4 is composed of isolated ∞(Cd3Sb2Se12)n chains and 2D layers formed by the NaSen (n = 5, 6) units. Their optical performances (bandgap and Raman spectra) were also investigated. Moreover, theoretical calculation was used to analyze the structure–performance relationship of Na3CdSbSe4. [ABSTRACT FROM AUTHOR]

Ni–Fe asymmetric ring dots with partially planed outer sides were investigated as candidates for high-density magnetic memory cells. The magnetic states, which were measured with magnetic force microscopy, show that in-plane magnetic fields can control the chirality, either clockwise or counterclockwise, of vortical magnetizations of the Ni–Fe asymmetric ring dots. This control facilitates applying ring dots to the magnetic random access memories. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The read-cycle endurance of a magnetic tunneling junction (MTJ) has been investigated, focusing on the spin-dependent tunneling current at high temperatures. The MTJ structure used in this study consisted of Ta-NiFe-CoFe-AlOx-CoFe-IrMn-NiFe-Ta prepared on a thermally oxidized Si wafer. Both the tunneling current and tunneling magnetoresistance ratio showed no significant degradation during the 1E9 read-cycle test using unipolar voltage pulses of 0.5 V at room temperature. Temperature dependence of the MTJs resistance calculated from the measured tunneling current has also been examined in a temperature range from room temperature to 175 °C. Furthermore in the case of read-cycle tests for thermally stressed MTJs, the variation of the tunneling current was less than 2% after 1E9 cycles at a stress temperature of 175 °C. This indicates that MTJs have sufficient read-cycle endurance under high-temperature operation. [ABSTRACT FROM AUTHOR]

Two new quaternary chalcogenides, Na6CdSb4S10 and Na3CdSbSe4, were successfully synthesized by the high-temperature solid-state reaction in vacuum-sealed silica tubes. Note that Na6CdSb4S10 crystallizes in the C2/c space group, whereas Na3CdSbSe4 crystallizes in the P21/c space group. As seen from their structures, Na6CdSb4S10 exhibits a three-dimensional (3D) framework structure composed by the interconnection of isolated [(Cd/Sb)2Sb2S10] clusters and two different layers formed by the NaSn (n = 4, 6) units; besides, the structure of Na3CdSbSe4 is composed of isolated ∞(Cd3Sb2Se12)n chains and 2D layers formed by the NaSen (n = 5, 6) units. Their optical performances (bandgap and Raman spectra) were also investigated. Moreover, theoretical calculation was used to analyze the structure–performance relationship of Na3CdSbSe4. [ABSTRACT FROM AUTHOR]