Showing papers on "Electric field published in 2011"
TL;DR: In this paper, point defects in diamond known as nitrogen-vacancy centres have been shown to be sensitive to minute magnetic fields, even at room temperature, and a demonstration that the spin associated with these defect centres is also sensitive to electric fields holds out the prospect of a sensor that can resolve single spins and single elementary charges at the nanoscale.
Abstract: Point defects in diamond known as nitrogen-vacancy centres have been shown to be sensitive to minute magnetic fields, even at room temperature. A demonstration that the spin associated with these defect centres is also sensitive to electric fields holds out the prospect of a sensor that can resolve, under ambient conditions, single spins and single elementary charges at the nanoscale.
1,027 citations
TL;DR: In this paper, the magnetic component of terahertz transients enables ultrafast control of the spin degree of freedom in the NiO at frequencies as high as 1.5 GHz.
Abstract: Ultrafast charge and spin excitations in the elusive terahertz regime1,2 of the electromagnetic spectrum play a pivotal role in condensed matter3,4,5,6,7,8,9,10,11,12,13. The electric field of free-space terahertz pulses has provided a direct gateway to manipulating the motion of charges on the femtosecond timescale6,7,8,9. Here, we complement this process by showing that the magnetic component of intense terahertz transients enables ultrafast control of the spin degree of freedom. Single-cycle terahertz pulses switch on and off coherent spin waves in antiferromagnetic NiO at frequencies as high as 1 THz. An optical probe pulse with a duration of 8 fs follows the terahertz-induced magnetic dynamics directly in the time domain and verifies that the terahertz field addresses spins selectively by means of the Zeeman interaction. This concept provides a universal ultrafast means to control previously inaccessible magnetic excitations in the electronic ground state. Researchers report the direct observation of ultrafast magnetic dynamics using the magnetic component of highly intense terahertz wave pulses with a time resolution of 8 fs. This concept provides a universal ultrafast method of visualizing magnetic excitations in the electronic ground state.
817 citations
TL;DR: The triple-band absorber is a promising candidate as absorbing elements in scientific and technical applications because of its multiband absorption, polarization insensitivity, and wide-angle response.
Abstract: We report the design, fabrication, and measurement of a microwave triple-band absorber. The compact single unit cell consists of three nested electric closed-ring resonators and a metallic ground plane separated by a dielectric layer. Simulation and experimental results show that the absorber has three distinctive absorption peaks at frequencies 4.06GHz, 6.73GHz, and 9.22GHz with the absorption rates of 0.99, 0.93, and 0.95, respectively. The absorber is valid to a wide range of incident angles for both transverse electric (TE) and transverse magnetic (TM) polarizations. The triple-band absorber is a promising candidate as absorbing elements in scientific and technical applications because of its multiband absorption, polarization insensitivity, and wide-angle response.
637 citations
TL;DR: The devices show the unique characteristics of ferroelectric photovoltaic devices with switchable diode polarity and tunable efficiency, which are 10-20% higher than those achieved by other methods, such as morphology and electrode work-function optimization.
Abstract: The recombination of electrons and holes in semiconducting polymer–fullerene blends has been identified as a main cause of energy loss in organic photovoltaic devices. Generally, an external bias voltage is required to efficiently separate the electrons and holes and thus prevent their recombination. Here we show that a large, permanent, internal electric field can be ensured by incorporating a ferroelectric polymer layer into the device, which eliminates the need for an external bias. The electric field, of the order of 50 V μm−1, potentially induced by the ferroelectric layer is tens of times larger than that achievable by the use of electrodes with different work functions. We show that ferroelectric polymer layers enhanced the efficiency of several types of organic photovoltaic device from 1–2% without layers to 4–5% with layers. These enhanced efficiencies are 10–20% higher than those achieved by other methods, such as morphology and electrode work-function optimization. The devices show the unique characteristics of ferroelectric photovoltaic devices with switchable diode polarity and tunable efficiency. One of the key loss mechanisms in the operation of organic solar cells is the separation and extraction of the generated charge carriers from the active region. The use of a ferroelectric layer is now shown to create large internal electric fields, resulting in an enhanced carrier extraction and increased device efficiency.
492 citations
TL;DR: A transport study of exfoliated few monolayer crystals of topological insulator Bi2Se3 in an electric field effect geometry finds that the temperature T and magnetic field dependent transport properties in the vicinity of this V(g) can be explained by a bulk channel with activation gap of approximately 50 meV and a relatively high-mobility metallic channel that dominates at low T.
Abstract: We report a transport study of exfoliated few monolayer crystals of topological insulator Bi2Se3 in an electric field effect geometry. By doping the bulk crystals with Ca, we are able to fabricate devices with sufficiently low bulk carrier density to change the sign of the Hall density with the gate voltage V(g). We find that the temperature T and magnetic field dependent transport properties in the vicinity of this V(g) can be explained by a bulk channel with activation gap of approximately 50 meV and a relatively high-mobility metallic channel that dominates at low T. The conductance (approximately 2×7e2/h), weak antilocalization, and metallic resistance-temperature profile of the latter lead us to identify it with the protected surface state. The relative smallness of the observed gap implies limitations for electric field effect topological insulator devices at room temperature.
451 citations
TL;DR: Electric field–induced ferromagnetism at room temperature in a magnetic oxide semiconductor, (Ti,Co)O2, is demonstrated by means of electric double-layer gating with high-density electron accumulation and revealing the considerable role of electron carriers in high-temperature ferromagnetic state and demonstrating a route to room-tem temperature semiconductor spintronics.
Abstract: The electric field effect in ferromagnetic semiconductors enables switching of the magnetization, which is a key technology for spintronic applications. We demonstrated electric field–induced ferromagnetism at room temperature in a magnetic oxide semiconductor, (Ti,Co)O2, by means of electric double-layer gating with high-density electron accumulation (>1014 per square centimeter). By applying a gate voltage of a few volts, a low-carrier paramagnetic state was transformed into a high-carrier ferromagnetic state, thereby revealing the considerable role of electron carriers in high-temperature ferromagnetism and demonstrating a route to room-temperature semiconductor spintronics.
438 citations
TL;DR: In this article, the effects of alignment on charge-carrier properties of Discotic Liquid Crystals (DLCs) are discussed, and a detailed overview of the current state of the art is provided.
Abstract: Discotic liquid crystals (DLCs) have been exploited in opto-electronic devices for their advantageous properties including long-range self-assembling, self-healing, ease of processing, solubility in a variety of organic solvents, and high charge-carrier mobilities along the stacking axis. An overview of DLCs and their charge-carrier mobilities, theoretical modeling, alignment, and device applications is addressed herein. The effects of alignment on charge-carrier properties of DLCs are discussed. Particular attention is devoted to processing techniques that achieve suitable alignment of DLCs for efficient electronic devices such as zone-casting, zone melting, Langmuir−Blodgett deposition, solution-casting on preoriented polytetrafluoroethylene (PTFE), surface treatment, IR irradiation, application of a magnetic field, use of sacrificial layers, use of blends, application of an electric field, and others.
426 citations
TL;DR: A nonvolatile, room temperature magnetization reversal determined by an electric field in a ferromagnet-multiferroic system demonstrates an avenue for next-generation, low-energy consumption spintronics.
Abstract: A reversal of magnetization requiring only the application of an electric field can lead to low-power spintronic devices by eliminating conventional magnetic switching methods. Here we show a nonvolatile, room temperature magnetization reversal determined by an electric field in a ferromagnet-multiferroic system. The effect is reversible and mediated by an interfacial magnetic coupling dictated by the multiferroic. Such electric-field control of a magnetoelectric device demonstrates an avenue for next-generation, low-energy consumption spintronics.
422 citations
TL;DR: In this article, the authors generalized the HSD model to include the creation and evolution of electromagnetic fields as well as the influence of the magnetic and electric fields on the quasiparticle propagation.
Abstract: The hadron string dynamics (HSD) model is generalized to include the creation and evolution of retarded electromagnetic fields as well as the influence of the magnetic and electric fields on the quasiparticle propagation. The time-space structure of the fields is analyzed in detail for noncentral Au $+$ Au collisions at $\sqrt{{s}_{\mathit{NN}}}=200$ GeV. It is shown that the created magnetic field is highly inhomogeneous, but in the central region of the overlapping nuclei it changes relatively weakly in the transverse direction. For the impact parameter $b=10$ fm, the maximal magnetic field--- perpendicularly to the reaction plane---is obtained of order ${\mathit{eB}}_{y}/{m}_{\ensuremath{\pi}}^{2}~$5 for a very short time $~$0.2 fm/$c$, which roughly corresponds to the time of a maximal overlap of the colliding nuclei. We find that at any time, the location of the maximum in the ${\mathit{eB}}_{y}$ distribution correlates with that of the energy density of the created particles. In contrast, the electric field distribution, being also highly inhomogeneous, has a minimum in the center of the overlap region. Furthermore, the field characteristics are presented as a function of the collision energy and the centrality of the collisions. To explore the effect of the back reaction of the fields on hadronic observables, a comparison of HSD results with and without fields is exemplified. Our actual calculations show no noticeable influence of the electromagnetic fields---created in heavy-ion collisions---on the effect of the electric charge separation with respect to the reaction plane.
382 citations
TL;DR: A new concept for the controlled propulsion of conducting objects with sizes ranging from centimetres to hundreds of micrometres is presented, based on their polarization, induced by an electric field, which triggers spatially separated oxidation and reduction reactions involving asymmetric gas bubble formation.
Abstract: External electric fields have been used to control the motion of small objects through electrostatic repulsion. Here, electric fields are used to polarize conducting objects, triggering their movement by spatially separated electrochemical reactions leading to directionally controlled bubble evolution.
363 citations
TL;DR: In this article, the authors show that the electrical conductance at the interfacial ferroelectric domain walls in hexagonal ErMnO3 is a continuous function of the domain wall orientation, with a range of an order of magnitude.
Abstract: Transition metal oxides hold great potential for the development of new device paradigms because of the field-tunable functionalities driven by their strong electronic correlations, combined with their earth abundance and environmental friendliness. Recently, the interfaces between transition-metal oxides have revealed striking phenomena such as insulator-metal transitions, magnetism, magnetoresistance, and superconductivity. Such oxide interfaces are usually produced by sophisticated layer-by-layer growth techniques, which can yield high quality, epitaxial interfaces with almost monolayer control of atomic positions. The resulting interfaces, however, are fixed in space by the arrangement of the atoms. Here we demonstrate a route to overcoming this geometric limitation. We show that the electrical conductance at the interfacial ferroelectric domain walls in hexagonal ErMnO3 is a continuous function of the domain wall orientation, with a range of an order of magnitude. We explain the observed behaviour using first-principles density functional and phenomenological theories, and relate it to the unexpected stability of head-to-head and tail-to-tail domain walls in ErMnO3 and related hexagonal manganites. Since the domain wall orientation in ferroelectrics is tunable using modest external electric fields, our finding opens a degree of freedom that is not accessible to spatially fixed interfaces.
Journal Article•
TL;DR: Charge transport phenomena in multiferroic heterostructures, where both magnetic and ferroelectric order parameters are used to control charge transport, suggest new possibilities to control the conduction paths of the electron spin, with potential for device applications.
Abstract: We review the recent developments in the electric field control of magnetism in multiferroic heterostructures, which consist of heterogeneous materials systems where a magnetoelectric coupling is engineered between magnetic and ferroelectric components. The magnetoelectric coupling in these composite systems is interfacial in origin, and can arise from elastic strain, charge, and exchange bias interactions, with different characteristic responses and functionalities. Moreover, charge transport phenomena in multiferroic heterostructures, where both magnetic and ferroelectric order parameters are used to control charge transport, suggest new possibilities to control the conduction paths of the electron spin, with potential for device applications.
TL;DR: Recent progress in both synthetic strategies, which allow for material and architectural modulation of novel nanoheterostructures, as well as the experimental work that provides insight into the photophysical properties of type-II heterostructure are highlighted.
Abstract: The development of elegant synthetic methodologies for the preparation of monocomponent nanocrystalline particles has opened many possibilities for the preparation of heterostructured semiconductor nanostructures. Each of the integrated nanodomains is characterized by its individual physical properties, surface chemistry, and morphology, yet, these multicomponent hybrid particles present ideal systems for the investigation of the synergetic properties that arise from the material combination in a non-additive fashion. Of particular interest are type-II heterostructures, where the relative band alignment of their constituent semiconductor materials promotes a spatial separation of the electron and hole following photoexcitation, a highly desirable property for photovoltaic applications. This article highlights recent progress in both synthetic strategies, which allow for material and architectural modulation of novel nanoheterostructures, as well as the experimental work that provides insight into the photophysical properties of type-II heterostructures. The effects of external factors, such as electric fields, temperature, and solvent are explored in conjunction with exciton and multiexciton dynamics and charge transfer processes typical for type-II semiconductor heterostructures.
TL;DR: In this article, the results of Monte-Carlo simulations of electron-positron-photon cascades initiated by slow electrons in circularly polarized fields of ultrahigh strength are presented and discussed.
Abstract: The results of Monte-Carlo simulations of electron-positron-photon cascades initiated by slow electrons in circularly polarized fields of ultrahigh strength are presented and discussed. Our results confirm previous qualitative estimations [A. M. Fedotov et al., Phys. Rev. Lett. 105, 080402 (2010)] of the formation of cascades. This sort of cascade has revealed a new property of restoration of energy and dynamical quantum parameter due to acceleration of electrons and positrons by the field. This may become a dominating feature of laser-matter interactions at ultrahigh intensities. Our approach incorporates radiation friction acting on individual electrons and positrons.
TL;DR: In this article, the effects of frequency, temperature and microstructure (point defects, grain size and texture) on the ferroelectric properties of several Ferroelectric compositions, including BaTiO3, lead zirconate titanate (PZT), lead-free Na0.5K0.15Nd0.06FeO3.
Abstract: Triangular voltage waveform was employed to distinguish the contributions of dielectric permittivity, electric conductivity and domain switching in current-electric field curves. At the same time, it is shown how those contributions can affect the shape of the electric displacement — electric field loops (D–E loops). The effects of frequency, temperature and microstructure (point defects, grain size and texture) on the ferroelectric properties of several ferroelectric compositions is reported, including: BaTiO3; lead zirconate titanate (PZT); lead-free Na0.5K0.5NbO3; perovskite-like layer structured A2B2O7 with super high Curie point (Tc); Aurivillius phase ferroelectric Bi3.15Nd0.5Ti3O12; and multiferroic Bi0.89La0.05Tb0.06FeO3. This systematic study provides an instructive outline in the measurement of ferroelectric properties and the analysis and interpretation of experimental data.
01 Jun 2011
TL;DR: Sub-auroral electric fields play critical roles in energizing and transporting ring current ions, as well as convecting thermal plasma in the inner magnetosphere and in the mid- to low-latitude ionosphere as mentioned in this paper.
Abstract: Sub-auroral electric fields play critical roles in energizing and transporting ring current ions, as well as convecting thermal plasma in the inner magnetosphere and in the mid- to low-latitude ionosphere. A number of terms have been employed to describe the sub-auroral electric fields and many of these are specifically associated with processes established through their prior use in the literature. The continued use of descriptive terms such as penetration electric fields, polarization jets, and sub-auroral ion drifts could lead to misunderstanding, especially when comparing the broad/narrow, persistent/transient regions of sub-auroral electric field and plasma flow. An inclusive name for these phenomena is sub-auroral polarization streams (SAPS).
TL;DR: In this article, the influence of electrical and electromagnetic fields on grain boundary energetics and kinetics is unmistakable, and the fundamental mechanisms of these electrical interactions are discussed in the following ways: (i) dielectric loss and Joule heating in the crystal and at the grain boundary, (ii) coupling between mechanical stress and the electrochemical potential of charged species, (iii) interaction between applied electrical fields and the intrinsic fields that exist within the space charge layers, (iv) and the possibility of nucleating defect avalanches under electrical fields.
Abstract: Microwaves and spark plasma sintering (SPS) enhance sinterability. Simple electrical fields, applied by means of a pair of electrodes to bare specimens, have been shown to accelerate the rate of superplastic deformation, reduce the time and temperature for sintering, and to retard the rate of grain growth. By inference, the influence of electrical and electromagnetic fields on grain boundary energetics and kinetics is unmistakable. Often, in ceramics, grain boundaries are themselves endowed with space charge that can couple with externally applied fields. The frequency dependence of this coupling ranging from zero frequency to microwave frequencies is discussed. The classical approach for modeling grain growth, creep, and sintering, considers chemical diffusion (self-diffusion) under a thermodynamic driving force, underpinned by a physical mechanism that visualizes the flow of mass transport in a way that reproduces the phenomenological observations. In all instances, the final analytical result can be separated into a product of three functions: one of the grain size, the second related to the thermodynamic driving force, and the third to the kinetics of mass transport. The influence of an electrical field on each of these functions is addressed.The fundamental mechanisms of these electrical interactions are discussed in the following ways: (i) dielectric loss and Joule heating in the crystal and at the grain boundary, (ii) the coupling between mechanical stress and the electrochemical potential of charged species, (iii) the interaction between applied electrical fields and the intrinsic fields that exist within the space charge layers, (iv) and the possibility of nucleating defect avalanches under electrical fields. We limit ourselves to ceramics that have at least some degree of ionic character. In these experiments the electrical fields range from several volts to several hundred volts per centimeter, and the power dissipation from Joule heating is of the order of several watts per cubic centimeter of the specimen. Metals, where very high current densities are obtained at relatively low applied electric fields, leading to phenomenon such as electromigration, are not considered.
TL;DR: Capillarity can be used to direct anisotropic colloidal particles to precise locations and to orient them by using interface curvature as an applied field, and this feature is exploited to induce migration and assembly at preferred locations, and to create complex structures.
Abstract: Capillarity can be used to direct anisotropic colloidal particles to precise locations and to orient them by using interface curvature as an applied field. We show this in experiments in which the shape of the interface is molded by pinning to vertical pillars of different cross-sections. These interfaces present well-defined curvature fields that orient and steer particles along complex trajectories. Trajectories and orientations are predicted by a theoretical model in which capillary forces and torques are related to Gaussian curvature gradients and angular deviations from principal directions of curvature. Interface curvature diverges near sharp boundaries, similar to an electric field near a pointed conductor. We exploit this feature to induce migration and assembly at preferred locations, and to create complex structures. We also report a repulsive interaction, in which microparticles move away from planar bounding walls along curvature gradient contours. These phenomena should be widely useful in the directed assembly of micro- and nanoparticles with potential application in the fabrication of materials with tunable mechanical or electronic properties, in emulsion production, and in encapsulation.
TL;DR: In this paper, the ability of new nonlinear resistive materials to be tuned for specific applications is emphasized, which opens up new possibilities in designing electric field control of products for medium and high voltage applications.
Abstract: The article emphasizes the ability of new nonlinear resistive materials to be tuned for specific applications, which opens up new possibilities in designing electric field control of products for medium and high voltage applications.
TL;DR: In this article, the authors developed rigorous and accurate numerical tools for simulating electric double layers formed near ultramicroelectrodes and assessed the validity of existing models and identified the dominant physical phenomena that must be accounted for.
Abstract: This paper aims to develop rigorous and accurate numerical tools for simulating electric double layers formed near ultramicroelectrodes. It also aims to assess the validity of existing models and to identify the dominant physical phenomena that must be accounted for. The electric double layer capacitance was numerically predicted for spherical ultramicroelectrodes of various radii in aqueous electrolyte. The model accounted for the Stern and diffuse layers, the finite size of ions, and the dependency of the electrolyte dielectric permittivity on the local electric field. This study reveals that models reported in the literature suffer from severe limitations. First, it demonstrates that the electrolyte field-dependent dielectric permittivity significantly affects the predicted Stern layer and total specific capacitances and must be accounted for. The finite ion size and the Stern layer also need to be considered in simulating electric double layers under high concentrations and surface potential. This stu...
TL;DR: In this paper, a magnetoelectric polycrystalline Ni thin film and (011)-oriented [Pb(Mg1/3Nb2/3)O3](1−x)−[PbTiO3]x]x heterostructure was reported to exhibit a 300 Oe anisotropy field and a 50% change in magnetic remanence.
Abstract: We report giant reversible and permanent magnetic anisotropy reorientation in a magnetoelectric polycrystalline Ni thin film and (011)-oriented [Pb(Mg1/3Nb2/3)O3](1−x)–[PbTiO3]x heterostructure. The electric-field-induced magnetic anisotropy exhibits a 300 Oe anisotropy field and a 50% change in magnetic remanence. The important feature is that these changes in magnetization states are stable without the application of an electric field and can be reversibly switched by an electric field near a critical value (±Ecr). This giant reversible and permanent magnetization change is due to remanent strain originating from a non-180° ferroelectric polarization reorientation when operating the ferroelectric substrate in a specific non-linear regime below the electric coercive field.
TL;DR: In this article, the authors demonstrate the attosecond control of the collective electron motion and directional emission from isolated dielectric (SiO2) nanoparticles with phase-stabilized few-cycle laser fields.
Abstract: Collective electron motion in condensed matter typically unfolds on a sub-femtosecond timescale. The well-defined electric field evolution of intense, phase-stable few-cycle laser pulses provides an ideal tool for controlling this motion. The resulting manipulation of local electric fields at nanometre spatial and attosecond temporal scales offers unique spatio-temporal control of ultrafast nonlinear processes at the nanoscale, with important implications for the advancement of nanoelectronics. Here we demonstrate the attosecond control of the collective electron motion and directional emission from isolated dielectric (SiO2) nanoparticles with phase-stabilized few-cycle laser fields. A novel acceleration mechanism leading to the ejection of highly energetic electrons is identified by the comparison of the results to quasi-classical model calculations. The observed lightwave control in nanosized dielectrics has important implications for other material groups, including semiconductors and metals. A demonstration of attosecond control of the motion and directed emission of electrons from individual silica nanoparticles using few-cycle laser fields opens new possibilities to manipulate electronic processes in nanoscale systems.
TL;DR: In this article, it was shown that a time-varying vector potential acting on an atomic Bose-Einstein condensate can be generated that has the effect of an electric field on the atoms, even if these are neutral.
Abstract: In electromagnetism, the vector potential generates magnetic fields through its spatial variation and electric fields through its time dependence. Now, it is demonstrated that, by engineering a time-varying vector potential acting on an atomic Bose–Einstein condensate, a synthetic gauge field can be generated that has the effect of an electric field on the atoms, even if these are neutral.
TL;DR: In this paper, a pump-probe experiment using optical excitation and an electrical probe with a resolution of <100 ns was performed on bulk heterojunctions of poly(3-hexylthiophene) and poly(6,6)-phenylC71 butyric acid methyl ester.
Abstract: Time-delayed collection field (TDCF) experiments are performed on bulk heterojunctionsolarcellscomprisedofablendofpoly(3-hexylthiophene)and(6,6)-phenylC71 butyric acid methyl ester. TDCF is analogous to a pump-probe experiment using optical excitation and an electrical probe with a resolution of <100 ns. The number of free charge carriers extracted after a short delay is found to be independent of the electric field during illumination. Also, experiments performed with a variable delay between the optical excitation andtheelectricalprobedonotrevealanyevidenceforthegenerationofchargevia field-assisted dissociation of bound long-lived polaron pairs. Photocurrent transients are well fitted by computational drift diffusion simulations with only direct generation of free charge carriers. Withincreasingdelaytimesbetweenpumpandprobe,twolossmechanismsareidentified; first, charge-carriers areswept outofthe deviceby theinternalelectric field,and second,bimolecular recombination of the remaining carriers takes place with a reduced recombination coefficient.
TL;DR: In this paper, a single-cycle carrier-envelope phase locked THz pulses at a central frequency of 2.1 THz with MV/cm electric field strengths and magnetic field strengths beyond 0.3 T were presented.
Abstract: We present high-power single-cycle carrier-envelope phase locked THz pulses at a central frequency of 2.1 THz with MV/cm electric field strengths and magnetic field strengths beyond 0.3 T. The THz radiation is generated by optical rectification in an organic salt crystal 4-N,N-dimethylamino-4′-N′-methyl stilbazolium tosylate called DAST pumped with the signal wavelength of a powerful optical parametric amplifier. Conversion efficiencies of more than 2% are reported.
TL;DR: An overview of the current state-of-art technology in the field of DC-iDEP for the separation and trapping of inert particles and cells and insulating obstacle geometry designs and the characterization of device performance are discussed.
Abstract: Dielectrophoresis is a noninvasive, nondestructive, inexpensive, and fast technique for the manipulation of bioparticles. Recent advances in the field of dielectrophoresis (DEP) have resulted in new approaches for characterizing the behavior of particles and cells using direct current (DC) electric fields. In such approaches, spatial nonuniformities are created in the channel by embedding insulating obstacles in the channel or flow field in order to perform separation or trapping. This emerging field of dielectrophoresis is commonly termed DC insulator dielectrophoresis (DC-iDEP), insulator-based dielectrophoresis (iDEP), or electrodeless dielectrophoresis (eDEP). In many microdevices, this form of dielectrophoresis has advantages over traditional AC-DEP, including single material microfabrication, remotely positioned electrodes, and reduced fouling of the test region. DC-iDEP applications have included disease detection, separation of cancerous cells from normal cells, and separation of live from dead bacteria. However, there is a need for a critical report to integrate these important research findings. The aim of this review is to provide an overview of the current state-of-art technology in the field of DC-iDEP for the separation and trapping of inert particles and cells. In this article, a review of the concepts and theory leading to the manipulation of particles via DC-iDEP is given, and insulating obstacle geometry designs and the characterization of device performance are discussed. This review compiles and compares the significant findings obtained by researchers in handling and manipulating particles.
TL;DR: It is found that weak electric field stimulation (pulse duration of 10 s) as low as 4.5 mV/mm for 32 min was particularly effective in shaping cell-to-cell interaction, which may open a new therapeutic approach for augmenting cell- to-cell coupling in cell transplantation therapy in the central nervous system.
TL;DR: It is shown that a 1-MVcm−1 electric field of a terahertz pulse, unlike a DC bias, can generate a substantial number of electron–hole pairs, forming excitons that emit near-infrared luminescence.
Abstract: The study of carrier multiplication has become an essential part of many-body physics and materials science as this multiplication directly affects nonlinear transport phenomena, and has a key role in designing efficient solar cells and electroluminescent emitters and highly sensitive photon detectors. Here we show that a 1-MVcm(-1) electric field of a terahertz pulse, unlike a DC bias, can generate a substantial number of electron-hole pairs, forming excitons that emit near-infrared luminescence. The bright luminescence associated with carrier multiplication suggests that carriers coherently driven by a strong electric field can efficiently gain enough kinetic energy to induce a series of impact ionizations that can increase the number of carriers by about three orders of magnitude on the picosecond time scale.
TL;DR: Unlike α- and γ-mode operation, electrons accelerated by strong drift and ambipolar electric fields in the plasma bulk and at the sheath edges are found to dominate the ionization in strongly electronegative discharges.
Abstract: Unlike � - and � -mode operation, electrons accelerated by strong drift and ambipolar electric fields in the plasma bulk and at the sheath edges are found to dominate the ionization in strongly electronegative discharges. These fields are caused by a low bulk conductivity and local maxima of the electron density at the sheath edges, respectively. This drift-ambipolar mode is investigated by kinetic particle simulations, experimental phase-resolved optical emission spectroscopy, and an analytical model in CF4. Mode transitions induced by voltage and pressure variations are studied.
TL;DR: In this paper, a laser-accelerated proton beam maximum energy cutoff of 675 MeV with more than 5'×'106 protons per MeV at that energy, using flat-top hollow microcone targets.
Abstract: We present experimental results showing a laser-accelerated proton beam maximum energy cutoff of 675 MeV, with more than 5 × 106 protons per MeV at that energy, using flat-top hollow microcone targets This result was obtained with a modest laser energy of ∼80 J, on the high-contrast Trident laser at Los Alamos National Laboratory From 2D particle-in-cell simulations, we attribute the source of these enhanced proton energies to direct laser-light-pressure acceleration of electrons along the inner cone wall surface, where the laser light wave accelerates electrons just outside the surface critical density, in a potential well created by a shift of the electrostatic field maximum with respect to that of the magnetic field maximum Simulations show that for an increasing acceleration length, the continuous loading of electrons into the accelerating phase of the laser field yields an increase in high-energy electrons