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Asymmetric Bias Dependence in Double Spin Filter Tunnel Junctions

G. X. Miao、J. S. Moodera2009-04-28arXiv

In double spin filter (SF) tunnel junctions, the spin information is generated and analyzed purely from the SF effect with nonmagnetic electrodes. In this article we numerically evaluate the bias dependence of magnetoresistance in such tunnel junctions (nonmagnetic metal / SF / nonmagnetic insulator / SF / nonmagnetic…

Materials Science

Atomic hydrogen adsorption and incipient hydrogenation of the Mg(0001) surface: A density-functional theory study

Yanfang Li、Ping Zhang、Bo Sun 等 5 位作者2009-04-28arXiv

We investigate the atomic hydrogen adsorption on Mg(0001) by using density-functional theory within the generalized gradient approximation and a supercell approach. The coverage dependence of the adsorption structures and energetics is systematically studied for a wide range of coverage and adsorption sites. In the co…

cond-mat.otherMaterials Science

Polar phonons in some compressively stressed epitaxial and polycrystalline SrTiO3 thin films

D. NUZHNYY、J. PETZELT、S. Kamba 等 8 位作者2009-04-28arXiv

Several SrTiO3 (STO) thin films without electrodes processed by pulsed laser deposition, of thicknesses down to 40 nm, were studied using infrared transmission and reflection spectroscopy. The complex dielectric responses of polar phonon modes, particularly ferroelectric soft mode, in the films were determined quantit…

Materials Science

Oxide layer boron leads to reduced symmetry spin filtering magnetic tunnel junctions

Derek A. Stewart2009-04-28arXiv

Experimental studies of FeCoB/MgO/FeCoB tunnel junctions indicate that boron diffuses into MgO during rf-sputtering and forms polycrystalline Mg-B-O regions. These tunnel junctions provide high tunneling magnetoresistance values and low RA products. However the crystal structure of the Mg-B-O region remains unknown. U…

Mesoscale and Nanoscale PhysicsMaterials Science

Lyman spectra of holes bound to Cu, Ag, and Au acceptors in ZnTe and CdTe

Gang Chen、I. Miotkowski、A. K. Ramdas2009-04-28arXiv

The group IB impurities (Cu, Ag, and Au) incorporated into II-VI zinc blende hosts of ZnTe and CdTe exhibit well resolved excitation lines followed by a photoionization continuum in their infrared absorption spectra. They are associated with transitions from a "1s-like" ground state to various "p-like" excited state c…

Materials Science

Tracing the thermal mechanism in femtosecond spin dynamics

U. Atxitia、O. Chubykalo-Fesenko、J. Walowski 等 5 位作者2009-04-28arXiv

We compare femtosecond pump-probe experiments in Ni and micromagnetic modelling based on the Landau-Lifshitz-Bloch equation coupled to a two-temperature model, revealing a predominant thermal ultrafast demagnetization mechanism. We show that both spin (femtosecond demagnetization) and electron-phonon (magnetization re…

cond-mat.stat-mechMaterials Science

Organic molecular thin films for nanoscale information memory applications

J. C. Li2009-04-28arXiv

According to Moore law, the silicon semiconductor transistor based information system is facing its physical limitations due to fluctuations of random charge and leakage current. Molecular electronics is becoming more and more attractive owing to the advantages of easy molecular structure variability, flexibility, low…

Materials Science

Adsorption and onset of lubrication by a double-chained cationic surfactant on silica surfaces

L. Serreau、M. Beauvais、C. Heitz 等 4 位作者2009-04-28arXiv

In the context of glass fiber manufacturing the onset of lubrication by a C18 double-chained cationic surfactant has been investigated at high normal contact pressures. Comparison with adsorption kinetics demonstrates that lubrication is not directly connected to the surfactant surface excess but originates from the t…

Materials Science

Electronic properties of single-crystallineFe1.05TeandFe1.03Se0.30Te0.70

Gui Chen、Zhiguo Chen、Jichen Dong 等 9 位作者2009-04-28Physical Review B

We report on a comprehensive study of the transport, specific heat, magnetic susceptibility, and optical spectroscopy on single crystal of ${\text{Fe}}_{1.05}\text{Te}$, which undergoes a first-order phase transition near 65 K. We show that its physical properties are considerably different from other parent compounds…

Intellectual Capital and Performance AnalysisCorporate Taxation and AvoidanceIron-based superconductors research

Identification of two hydrogen donors in ZnO

E. V. Lavrov、F. Herklotz、Jens Weber2009-04-28Physical Review B

A combined study of Raman scattering, IR absorption, photoluminescence, and photoconductivity was performed in ZnO. Two shallow donors---hydrogen at the bond-centered lattice site, ${\text{H}}_{\text{BC}}$, and hydrogen bound in an oxygen vacancy, ${\text{H}}_{\text{O}}$---were identified. Donor ${\text{H}}_{\text{BC}…

Electronic and Structural Properties of OxidesZnO doping and propertiesCopper-based nanomaterials and applications

Stability criteria for a passive electrostatic non-relativistic charged particle storage device

P. R. Hammond、T J Reddish、Aaron Alderman 等 5 位作者2009-04-27New Journal of Physics

The general conditions are determined for stable multiple orbits of non-relativistic charged particles in a race-track-shaped optical system.These conditions are then considered in the context of an electrostatic storage ring consisting of two 180 • hemispherical deflector analysers connected by two separate sets of c…

Atomic and Molecular PhysicsAtomic and Subatomic Physics ResearchElectron and X-Ray Spectroscopy Techniques

Efficient and Recyclable Phthalocyanine-Based Sensitizers for Photooxygenation Reactions

Dennis K. P. Ng、Hu Xu、Wing-Kin Chan2009-04-27Synthesis

Treatment of 4,5-bis(4-methoxycarbonylphen­oxy)phthalonitrile with Zn(OAc)2˙2H2O and 1,8-diazabicyclo[5.4.0]undec-7-ene in octan-1-ol or dodecan-1-ol led to base-promoted cyclotetramerization. Under these conditions, transesterification also occurred to give the corresponding zinc(II) octakis(4-alkoxycarbonylphenoxyph…

Photochromic and Fluorescence ChemistryOxidative Organic Chemistry ReactionsPorphyrin and Phthalocyanine Chemistry

Viscoelastic Composite Materials

Roderic S. Lakes2009-04-27Cambridge University Press eBooks

Introduction Composite materials are those that contain two or more distinct constituent materials or phases, on a microscopic or macroscopic size scale larger than the atomic scale, and in which physical properties are significantly altered in comparison with those of a homogeneous material. In this vein, fiberglass…

Material Properties and ApplicationsMaterial Properties and ProcessingFiber-reinforced polymer composites

Fire Retardancy of Polypropylene Composites Using Intumescent Coatings

Sophie Duquesne、Nicolas Renaut、P. Bardollet 等 6 位作者2009-04-27ACS symposium series

The aim of this study is to evaluate potential application of an intumescent coating in order to fire retard polypropylene composites. Using intumescent coatings and specific surface treatments such as cold plasma treatment prior to making the deposit, PP composites presenting a UL94 V-0 classification at low thicknes…

Fiber-reinforced polymer compositesFlame retardant materials and propertiesSurface Modification and Superhydrophobicity

Metal‐exchanged clay and zeolite additives as smoke suppressants and fire retardants for poly(vinyl chloride)

Alexander G. Zestos、Cole L. Grinnell、Long J. Vinh 等 5 位作者2009-04-27Journal of Vinyl and Additive Technology

Abstract Cone calorimetry studies showed that various metal‐exchanged clays and zeolites containing only 3–4% of Cu(II), Cu(I), Zn(II), or Al(III) were effective smoke suppressants and fire retardants for plasticized poly(vinyl chloride). Copper(II)‐Zn(II) and Cu(II)‐Al(III) synergism for smoke and heat reduction was…

Polymer Science and PVCPolymer Nanocomposites and PropertiesFlame retardant materials and properties

Liquid-Phase Oxidation of Some Aromatic Aldehydes, Hydrocarbons, and Alcohols by Cerium(IV) Catalyzed by Iridium(III) in Acidic Medium

Praveen K. Tandon、Priy Brat Dwivedi、Satpal Singh2009-04-27Synthetic Communications

Addition of traces of iridium(III) chloride with cerium(IV) sulfate (catalyst–substrate ratio (1:2994 to 1:10,000) in traditional water-bath heating resulted in the oxidation of p-chlorobenzaldehyde, p-nitrobenzaldehyde, benzyl alcohol, p-methoxy benzyl alcohol, p-xylene, and p-nitrotoluene dissolved in acetic acid to…

Mesoporous Materials and CatalysisCatalysis and Oxidation ReactionsOxidative Organic Chemistry Reactions

Synthesis and Characterization of Some Novel Dichromophoric Cyanine Dyes

Farahnaz Nourmohammadian、Mahnaz D. Gholami2009-04-27Synthetic Communications

Here, the synthesis of two novel series of dichromophoric cyanine dyes were reported. The first series of novel bis-azacyanine dyes 3a–d was afforded by reaction of 2-(1,3,3-trimethyle indoline-2-ylidene)acetaldehyde with diaminoaromatics, and the second series of novel bis-diazacyanine dyes 4a–d was obtained using qu…

Photodynamic Therapy Research StudiesPhotochromic and Fluorescence ChemistryPorphyrin and Phthalocyanine Chemistry

Purification, crystallization and preliminary X-ray analysis of isocitrate dehydrogenase kinase/phosphatase fromEscherichia coli

Jimin Zheng、Daniel Lee、Zongchao Jia2009-04-27Acta Crystallographica Section F Structural Biology and Crystallization Communications

The Escherichia coli aceK gene encodes isocitrate dehydrogenase kinase/phosphatase (EC 2.7.11.5), a bifunctional protein that phosphorylates and dephosphorylates isocitrate dehydrogenase (IDH), resulting in its inactivation and activation, respectively. This reversible (de)phosphorylation directs isocitrate, an interm…

Biochemical and Molecular ResearchEnzyme Structure and FunctionProtein Structure and Dynamics

Prediction of the effective dielectric constant in SWNT polyimide nanocomposites using the Bruggemann model

Ricardo Pérez2009-04-27Journal of Applied Polymer Science

Abstract The Bruggemann model is used in this work to predict the effective dielectric constant of two kinds of single‐wall carbon nanotube (SWNT) polyimide nanocomposites. Electrical conductivity and dielectric constant exhibit a dramatic enhancement at low content of SWNT fillers with a percolation threshold at 0.06…

Dielectric materials and actuatorsPolymer Nanocomposites and PropertiesCarbon Nanotubes in Composites

Effects of Fire Retardants and Nanofillers on the Fire Toxicity

Anna A. Stec、T. Richard Hull、José L. Torero 等 11 位作者2009-04-27ACS symposium series

Four polymers, polyamide 6, polypropylene, ethylene vinyl acetate and polybutylene terephthalate have been prepared with fire retardants, nanofillers, (both separately and together). The toxic product yield of each material has then been measured under different fire conditions. The influence of polymer nanocomposites…

Flame retardant materials and propertiesFiber-reinforced polymer compositesFire dynamics and safety research