Results 1 - 10 of 18
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[en] The perpendicular magnetic anisotropy (PMA) and the anomalous Hall effect (AHE) in Co/Ni multilayer were optimized by manipulating its interface structure (inducing HfO_2 capping layer and Pt insertion) and post-annealing treatment. A strong PMA can be obtained in Co/Ni multilayers with HfO_2 capping layer even after annealing at 400 °C. The heavy metal Hf may improve the interfacial spin-orbit coupling, which responsible for the enhanced PMA and high annealing stability. Moreover, the multilayer containing HfO_2 capping layer also exhibited high saturation anomalous Hall resistivity through post-annealing, which is 0.85 μΩ cm after annealing at 375 °C, 211% larger than in the sample at deposited state which is only 0.27 μΩ cm. The enhancement of AHE is mainly attributed to the interface scattering through post-annealing treatment. - Highlights: • The perpendicular magnetic anisotropy and anomalous Hall effect of Co/Ni multilayer films were studied. • The PMA thermal stability of the Co/Ni ML can be enhanced by HfO_2 capping layer and Pt insertion. • The anomalous Hall resistivity of Co/Ni ML covered by HfO_2 was enhanced by post-annealing treatment.
[en] A recombinant cyclic imide hydrolase from P. putida YZ-26 has been crystallized by the hanging-drop method. This will be helpful in understanding the role of CIH in pyrimidine metabolism and organic acid bioconversion. A recombinant form of cyclic imide hydrolase from Pseudomonas putida YZ-26 has been crystallized by the hanging-drop method. X-ray diffraction data were collected to 1.9 Å resolution. The crystals belonged to the orthorhombic space group C2221, with unit-cell parameters a = 111.91, b = 176.04, c = 176.06 Å. Assuming the presence of four molecules in the asymmetric unit gives a VM value of 3.10 Å3 Da−1 and a solvent content of 60.31%
[en] The resistive switching (RS) characteristics of a Bi0.95La0.05FeO3 (La-BFO) film sandwiched between a Pt bottom electrode and top electrodes (TEs) made of Al, Ag, Cu, and Au have been studied. Devices with TEs made of Ag and Cu showed stable bipolar RS behaviors, whereas those with TEs made of Al and Au exhibited unstable bipolar RS. The Ag/La-BFO/Pt structure showed an on/off ratio of 102, a retention time > 105 s, and programming voltages < 1 V. The RS effect can be attributed to the formation/rupture of nanoscale metal filaments due to the diffusion of the TEs under a bias voltage. The maximum current before the reset process (on-to-off switching) was found to increase linearly with the current compliance applied during the set process (off-to-on switching).
[en] We report an improvement in minimizing the dispersion of resistive switching (RS) parameters such as ON/OFF state resistances and switching voltages of Cu/ZnO/Pt structures in which ZnO films have been deposited at elevated temperature with N doping. This deposition process can enlarge the ZnO grain size and lessen grain boundaries while maintaining a high initial resistance since ZnO naturally shows n-type conductivity and N is a p-type dopant but with a low solubility. Cu filaments with a diameter of 15 nm are found to form at the ZnO grain boundaries. Therefore, fewer grain boundaries could depress the randomicity of the formation/rupture of Cu filaments and result in more stable RS performances. Such memory devices show a fast programming speed of 10 ns.
[en] This paper reports the cloning, expression, purification, crystallization and preliminary X-ray crystallographic analysis of the first C2 domain of synaptotagmin 5. Synaptotagmin acts as the Ca2+ sensor for neural and endocrine exocytosis. Synaptotagmin 5 has been demonstrated to play a key role in the acquisition of cathepsin D and the vesicular proton ATPase and in Ca2+-dependent insulin exocytosis. The C2 domains modulate the interaction of synaptotagmin with the phospholipid bilayer of the presynaptic terminus and effector proteins such as the SNARE complex. This study reports the cloning, expression in Escherichia coli, purification, crystallization and preliminary X-ray analysis of the C2A domain of human synaptotagmin 5 with an N-terminal His6 tag. The crystals diffracted to 1.90 Å resolution and belonged to the hexagonal space group P65, with unit-cell parameters a = b = 93.97, c = 28.05 Å. A preliminary model of the protein structure has been built and refinement of the model is ongoing
[en] We investigated capacitors based on polycrystalline narrow-band-gap BiFeO3 (BFO) thin films with different top electrodes. The photovoltaic response for the capacitor with a Sn-doped In2O3 (ITO) top electrode is about 25 times higher than that with a Au top electrode, which indicates that the electrode plays a key role in determining the photovoltaic response of ferroelectric thin film capacitors, as simulated by Qin et al (2009 Appl. Phys. Lett. 95 22912). The light-to-electricity photovoltaic efficiency for the ITO/polycrystalline BFO/Pt capacitor can reach 0.125%. Furthermore, under incident light of 450 μW cm-2 and zero bias, the corresponding photocurrent varies from 0.2 to 200 pA, that is, almost a 1000-fold photoconductivity enhancement. Our experiments suggest that polycrystalline BFO films are promising materials for application in photo-sensitive and energy-related devices.
[en] Optical pumping experiments at 377 nm on the resonance transition of atomic thallium (6p1/2-7s1/2) are reported. The potential of this technique in the search for an electric dipole moment which arises through PT-violation is assessed. Linewidths of radiofrequency resonances within the ground state are measured and effects of coherent population trapping, laser linewidth and collisions are all considered. Some theoretical modelling is also presented. (author)
[en] The leakage current and resistive switching (RS) of Ce-doped BiFeO3 (BCFO) films prepared by the sol-gel method at various annealing temperatures are investigated. With increasing annealing temperature, BCFO changes from an amorphous structure to a crystalline structure, while the leakage current increases due to an increase in the carrier mobility as well as an increase in the oxygen vacancy concentration. Bipolar RS behaviours are observed in BCFO films, which can be attributed to the formation/rupture of metal filaments due to the diffusion of the top electrodes under a bias voltage. With increasing annealing temperature, the forming voltage decreases, while no obvious changes are observed in resistances in both ON and OFF states and programming voltages, demonstrating that the RS occurs in a confined region. The pristine BCFO shows Schottky emission conduction behaviour, while Ohmic conduction and space charge limited conduction dominate in ON and OFF states, respectively.
[en] Solid-state incandescent light-emission devices (SSI-LEDs) with a metal-oxide-semiconductor structure are promising candidates for future broadband light-emission devices. In this work, the electrical and light-emission features of SSI-LEDs based on HfO2 high- k thin films with or without the Ti-embedded layer on p-type silicon wafers have been studied. It turns out that the Ti-embedded layer can effectively reduce the turn-on voltage, thus improving the fluorescence efficiency of SSI-LEDs. The combination of scanning electron microscopy, atomic force microscope (AFM) and conductive AFM results unambiguously clarifies that conductive filaments, which are formed due to local thermal excitation during the forming process, are accompanied by the formation of pits on the HfO2 surface and are responsible for the light emission. This work develops an effective approach to improving the luminescence performance of SSI-LEDs and experimentally explains the light-emitting mechanism of such devices, which is of great importance to eventually realizng broadband light-emitting devices with low power consumption. (paper)
[en] Freestanding Pb(Zr,Ti)O3 (PZT) thin membranes were fabricated by pulsed laser deposition on 200 nm-thick Pt foils which were obtained by etching the platinized Si substrates with HF solutions. X-ray diffraction patterns and Raman spectra show that the crystal lattice distortion of the PZT membranes is relaxed after removing the rigid substrates. Compared with the substrate-clamped PZT films, the saturation polarization and the remanent polarization of the freestanding PZT membranes are increased by about 18% and 21%, respectively. In addition, the freestanding PZT thin membranes possess higher dielectric tunability and larger domain size. The novel facile fabrication method is important for developing flexible ferroelectric devices and also for studying the strain effects on the physical properties of flexible functional membranes. (paper)