Search results for "Optical"
showing 10 items of 7671 documents
Magnetic nanoparticles between electrodes of tunnel junction: anomalous tunnel conductance
2002
Abstract Magnetic particles of microscopic size can be created in the process of Ni, Fe and Co mechanically controllable break junctions fabrication and trapped between the electrodes by magnetic dipole forces. Tunneling between the protruding nanoparticle and the sample electrode shows clear distinctions from the usual junctions: heavy deviation of the current–distance I(z) dependence from the expected exponential behavior at electrode separations z below 4.0– 4.5 A and on numerous occasions a sudden jump-like decrease of the tunnel current at z≈1.5– 2.0 A . Possible mechanisms behind observed anomalies including the short-range magnetic exchange coupling are discussed.
Probing the electronic states of high-TMR off-stoichiometric Co2MnSi thin films by hard x-ray photoelectron spectroscopy
2014
The tunnel magnetoresistance ratio (TMR) of fully epitaxial magnetic tunnel junctions with an off-stoichiometric Co${}_{2}$MnSi Heusler alloy has been shown to exhibit a systematic dependence on Mn content, reaching 1135% at 4.2 K for Co${}_{2}$Mn${}_{1.29}$Si. In this paper, we explain the behavior of the observed TMR ratio using ab initio calculations and hard x-ray photoelectron spectroscopy (HAXPES). For the Mn-deficient samples, we show that the the drop of the TMR is caused by Co antisite atoms, which impose extra states into the minority-spin band gap. On the other hand, Mn-excess composition shows nearly half-metallic behavior. This result can be intuitively understood since both Co…
Supramolecular self-assembly on the B-Si(111)-(√3x√3) R30° surface: From single molecules to multicomponent networks
2017
Abstract Understanding the physical and chemical processes in which local interactions lead to ordered structures is of particular relevance to the realization of supramolecular architectures on surfaces. While spectacular patterns have been demonstrated on metal surfaces, there have been fewer studies of the spontaneous organization of supramolecular networks on semiconductor surfaces, where the formation of covalent bonds between organics and adatoms usually hamper the diffusion of molecules and their subsequent interactions with each other. However, the saturation of the dangling bonds at a semiconductor surface is known to make them inert and offers a unique way for the engineering of m…
Characterization of dual-polarization analogue radio over fiber fronthaul for LTE C-RAN architecture
2016
En este artículo se presentan los resultados de la medición ampliada de la radio analógica de doble polarización (DP) sobre fibra (RoF) en una arquitectura de red de acceso radio en la nube (C-RAN) de evolución a largo plazo (LTE). Esta técnica se propone para las conexiones de fibra entre las oficinas centrales y las estaciones base remotas. Se investigan varias longitudes de fibra óptica para determinar el mejor rendimiento del sistema en términos de magnitud de vector de error (EVM) y tasa de error de bit. La distancia máxima alcanzada para el caso de un ancho de banda LTE de 20 MHz es de 50 km, mostrando un valor de EVM admisible del 8,5% a la frecuencia de radio de 2,6 GHz cuando se ut…
Inverse nonlinear design in silicon waveguides
2014
La tecnologia fotònica basada en silici és objecte d'intensa investigació tant al món acadèmic com a la indústria. Un dels seus principals atractius rau en la seua elevada compatibilitat amb tècniques ja desenvolupades per a la integració de circuits electrònics, cosa que podria reduir el seu cost. A més, el silici ofereix una gran diversitat d'efectes no lineals que poden ser aprofitats per processar senyals òptics en xips compactes a velocitats superiors als dispositius electrònics actuals. En particular, l'objectiu d'aquesta tesi ha estat dissenyar una guia integrada en una plataforma híbrida de silici i sílice per generar espectres supercontinus. Aquest projecte presentava diferents rep…
Hybrid materials with nanoscopic anion-binding pockets for the colorimetric sensing of phosphate in water using displacement assays
2008
Mesoporous amino-functionalised solids containing certain dyes have been used as suitable anion hosts in displacement assays for the colorimetric signalling of phosphate in water. Amoros del Toro, Pedro Jose, Pedro.Amoros@uv.es
Reduction of tris(benzene-1,2-dithiolate)molybdenum(VI) by hydroxide ions in dry tetrahydrofuran solution.
2001
Tris(benzene-1,2-dithiolate)molybdenum(VI) reacts rapidly and quantitatively with tetrabutylammonium hydroxide to yield the corresponding Mo(V) and Mo(IV) complexes and hydrogen peroxide; the reaction has been executed in dry tetrahydrofuran where the reaction rate shows a fair dependence on complex and OH2 concentrations. Cervilla Avalos, Antonio, Antonio.Cervilla@uv.es ; Perez Pla, Francisco, Francisco.Perez@uv.es ; Llopis Jover, Elisa, Elisa.Llopis@uv.es
The selective oxidative dehydrogenation of ethane over hydrothermally synthesised MoVTeNb catalysts
2002
Mo–V–Te–Nb metal oxide catalysts prepared by hydrothermal synthesis and heat-treated in N2 at high temperatures (600–700 °C) show high activity and selectivity for the oxidative dehydrogenation of ethane to ethene. Yields of ethene of 75% have been obtained at 400 °C on the best catalysts. Dejoz Garcia, Ana Maria, Ana.M.Dejoz@uv.es
[Fe(sal2-trien)][Ni(dmit)2]: towards switchable spin crossover molecular conductors
2004
A cooperative spin transition behaviour with a wide hysteresis loop (30 K) around 240 K has been observed, for the first time, in a salt based on the redox active [Ni(dmit)2]¯, anion and the [Fe(sal2-trien)]+ spin crossover cation. Real Cabezos, Jose Antonio, Jose.A.Real@uv.es
Coexistence of ferro- and antiferromagnetic interactions in a metal-organic radical-based (6,3)-helical network with large channels.
2005
A metal–organic open-framework with an unprecedented (6,3)-helical topology, large channels and mixed ferro- and antiferromagnetic interactions has been synthesized using a three-connecting tricarboxylic polychlorotriphenylmethyl radical and Co(II) ions. Lloret Pastor, Francisco, Francisco.Lloret@uv.es