Showing papers on "Electric field published in 2010"
TL;DR: It is demonstrated that strong magnetic fields can be induced in ferromagnetic metal films lacking structure inversion symmetry through the Rashba effect and this process makes it a realistic candidate for room-temperature spintronic applications.
Abstract: Methods to manipulate the magnetization of ferromagnets by means of local electric fields or current-induced spin transfer torque allow the design of integrated spintronic devices with reduced dimensions and energy consumption compared with conventional magnetic field actuation. An alternative way to induce a spin torque using an electric current has been proposed based on intrinsic spin-orbit magnetic fields and recently realized in a strained low-temperature ferromagnetic semiconductor. Here we demonstrate that strong magnetic fields can be induced in ferromagnetic metal films lacking structure inversion symmetry through the Rashba effect. Owing to the combination of spin-orbit and exchange interactions, we show that an electric current flowing in the plane of a Co layer with asymmetric Pt and AlO(x) interfaces produces an effective transverse magnetic field of 1 T per 10(8) A cm(-2). Besides its fundamental significance, the high efficiency of this process makes it a realistic candidate for room-temperature spintronic applications.
1,269 citations
878 citations
TL;DR: This article can reversibly switch between two distinct exchange-bias states by switching the ferroelectric polarization of BiFeO(3), an important step towards controlling magnetization with electric fields, which may enable a new class of electrically controllable spintronic devices and provide a new basis for producing electrically controlled spin-polarized currents.
Abstract: The control of magnetization by electric fields is important for applications in data storage and sensing. An efficient control of exchange bias by electric fields has now been achieved in thin-film devices in which a ferroelectric antiferromagnet is coupled to a ferromagnet.
628 citations
TL;DR: In this paper, it was shown that the (0001) surface of magnetoelectric Cr(2)O(3) has a roughness-insensitive, electrically switchable magnetization.
Abstract: Voltage-controlled spin electronics is crucial for continued progress in information technology. It aims at reduced power consumption, increased integration density and enhanced functionality where non-volatile memory is combined with high-speed logical processing. Promising spintronic device concepts use the electric control of interface and surface magnetization. From the combination of magnetometry, spin-polarized photoemission spectroscopy, symmetry arguments and first-principles calculations, we show that the (0001) surface of magnetoelectric Cr(2)O(3) has a roughness-insensitive, electrically switchable magnetization. Using a ferromagnetic Pd/Co multilayer deposited on the (0001) surface of a Cr(2)O(3) single crystal, we achieve reversible, room-temperature isothermal switching of the exchange-bias field between positive and negative values by reversing the electric field while maintaining a permanent magnetic field. This effect reflects the switching of the bulk antiferromagnetic domain state and the interface magnetization coupled to it. The switchable exchange bias sets in exactly at the bulk Neel temperature.
507 citations
TL;DR: In this article, a nearly omnidirectional THz absorber for both transverse electric (TE) and transverse magnetic (TM) polarizations is proposed, where the excitation of the magnetic polariton in a metal-dielectric layer is perfectly absorbed in a thin thickness that is about 25 times smaller than the resonance wavelength.
Abstract: A nearly omnidirectional THz absorber for both transverse electric (TE) and transverse magnetic (TM) polarizations is proposed. Through the excitation of the magnetic polariton in a metal-dielectric layer, the incident light is perfectly absorbed in a thin thickness that is about 25 times smaller than the resonance wavelength. By simply stacking several such structural layers with different geometrical dimensions, the bandwidth of this strong absorption can be effectively enhanced due to the hybridization of magnetic polaritons in different layers.
482 citations
TL;DR: In this article, the effect of applied electric field EG on thickness dependent magnetic anisotropy of sputtered Co40Fe40B20 sandwiched with MgO and Ta was investigated.
Abstract: We have investigated the effect of applied electric field EG on thickness dependent magnetic anisotropy of sputtered Co40Fe40B20 sandwiched with MgO and Ta. The range of CoFeB thickness explored is 2 nm and below. As the thickness is reduced, the easy axis of magnetization becomes perpendicular from in-plane. We show that perpendicular magnetic anisotropy of in-plane samples and coercivity of perpendicular samples can be modified by applying EG at room temperature. Furthermore, superparamagnetic behavior is observed for CoFeB layers with further reduced thickness below ≈0.9 nm, where electric-field effect is also observed below their blocking temperature.
463 citations
TL;DR: The data and mechanistic framework provide a functional role for endogenous electric fields, specifically illustrating that modulation of gamma oscillations during theta-modulated gamma activity can result from field effects alone.
Abstract: Clinical effects of transcranial electrical stimulation with weak currents are remarkable considering the low amplitude of the electric fields acting on the brain. Elucidating the processes by which small currents affect ongoing brain activity is of paramount importance for the rational design of noninvasive electrotherapeutic strategies and to determine the relevance of endogenous fields. We propose that in active neuronal networks, weak electrical fields induce small but coherent changes in the firing rate and timing of neuronal populations that can be magnified by dynamic network activity. Specifically, we show that carbachol-induced gamma oscillations (25–35 Hz) in rat hippocampal slices have an inherent rate-limiting dynamic and timing precision that govern susceptibility to low-frequency weak electric fields (<50 Hz; <10 V/m). This leads to a range of nonlinear responses, including the following: (1) asymmetric power modulation by DC fields resulting from balanced excitation and inhibition; (2) symmetric power modulation by lower frequency AC fields with a net-zero change in firing rate; and (3) half-harmonic oscillations for higher frequency AC fields resulting from increased spike timing precision. These underlying mechanisms were elucidated by slice experiments and a parsimonious computational network model of single-compartment spiking neurons responding to electric field stimulation with small incremental polarization. Intracellular recordings confirmed model predictions on neuronal timing and rate changes, as well as spike phase-entrainment resonance at 0.2 V/m. Finally, our data and mechanistic framework provide a functional role for endogenous electric fields, specifically illustrating that modulation of gamma oscillations during theta-modulated gamma activity can result from field effects alone.
458 citations
TL;DR: This work demonstrates a critical step to control and use non-volatile magnetoelectric coupling at the nanoscale and provides a framework for exploring a route to control multiple order parameters coupled to ferroelastic order in other low-symmetry materials.
Abstract: Multiferroics, where (anti-) ferromagnetic, ferroelectric and ferroelastic order parameters coexist, enable manipulation of magnetic ordering by an electric field through switching of the electric polarization. It has been shown that realization of magnetoelectric coupling in a single-phase multiferroic such as BiFeO(3) requires ferroelastic (71 degrees, 109 degrees) rather than ferroelectric (180 degrees) domain switching. However, the control of such ferroelastic switching in a single-phase system has been a significant challenge as elastic interactions tend to destabilize small switched volumes, resulting in subsequent ferroelastic back-switching at zero electric field, and thus the disappearance of non-volatile information storage. Guided by our phase-field simulations, here we report an approach to stabilize ferroelastic switching by eliminating the stress-induced instability responsible for back-switching using isolated monodomain BiFeO(3) islands. This work demonstrates a critical step to control and use non-volatile magnetoelectric coupling at the nanoscale. Beyond magnetoelectric coupling, it provides a framework for exploring a route to control multiple order parameters coupled to ferroelastic order in other low-symmetry materials.
411 citations
TL;DR: The origin of an apparent 'band-like', negative temperature coefficient of the mobility (dmu/dT<0) in spin-coated films of 6,13-bis(triisopropylsilylethynyl)-pentacene is investigated and optical spectroscopy of gate-induced charge carriers is used to show that, at low temperature and small lateral electric field, charges become localized onto individual molecules in shallow trap states, but that a moderate lateralElectric field
Abstract: The mobility mu of solution-processed organic semiconductors has improved markedly to room-temperature values of 1-5 cm(2) V(-1) s(-1). In spite of their growing technological importance, the fundamental open question remains whether charges are localized onto individual molecules or exhibit extended-state band conduction like those in inorganic semiconductors. The high bulk mobility of 100 cm(2) V(-1) s(-1) at 10 K of some molecular single crystals provides clear evidence that extended-state conduction is possible in van-der-Waals-bonded solids at low temperatures. However, the nature of conduction at room temperature with mobilities close to the Ioffe-Regel limit remains controversial. Here we investigate the origin of an apparent 'band-like', negative temperature coefficient of the mobility (dmu/dT<0) in spin-coated films of 6,13-bis(triisopropylsilylethynyl)-pentacene. We use optical spectroscopy of gate-induced charge carriers to show that, at low temperature and small lateral electric field, charges become localized onto individual molecules in shallow trap states, but that a moderate lateral electric field is able to detrap them resulting in highly nonlinear, low-temperature transport. The negative temperature coefficient of the mobility at high fields is not due to extended-state conduction but to localized transport limited by thermal lattice fluctuations.
396 citations
TL;DR: In this paper, it was shown that in the circuit-QED architecture, superconducting circuits can be inserted into the resonator junctions to break time-reversal symmetry.
Abstract: Breaking time-reversal symmetry is a prerequisite for accessing certain interesting many-body states such as fractional quantum Hall states. For polaritons, charge neutrality prevents magnetic fields from providing a direct symmetry-breaking mechanism and, similar to the situation in ultracold atomic gases, an effective magnetic field has to be synthesized. We show that in the circuit-QED architecture, this can be achieved by inserting simple superconducting circuits into the resonator junctions. In the presence of such coupling elements, constant parallel magnetic and electric fields suffice to break time-reversal symmetry. We support these theoretical predictions with numerical simulations for realistic sample parameters, specify general conditions under which time reversal is broken, and discuss the application to chiral Fock-state transfer, an on-chip circulator, and tunable band structure for the Kagome lattice.
358 citations
TL;DR: In this paper, the authors showed that transformer oil-based nanofluids with conductive nanoparticle suspensions have substantially higher positive voltage breakdown levels with slower positive streamer velocities than that of pure transformer oil.
Abstract: Transformer oil-based nanofluids with conductive nanoparticle suspensions defy conventional wisdom as past experimental work showed that such nanofluids have substantially higher positive voltage breakdown levels with slower positive streamer velocities than that of pure transformer oil. This paradoxical superior electrical breakdown performance compared to that of pure oil is due to the electron charging of the nanoparticles to convert fast electrons from field ionization to slow negatively charged nanoparticle charge carriers with effective mobility reduction by a factor of about 1×105. The charging dynamics of a nanoparticle in transformer oil with both infinite and finite conductivities shows that this electron trapping is the cause of the decrease in positive streamer velocity, resulting in higher electrical breakdown strength. Analysis derives the electric field in the vicinity of the nanoparticles, electron trajectories on electric field lines that charge nanoparticles, and expressions for the char...
TL;DR: In this article, the electric field perpendicular to the current flow was found to be significantly lower in junctionless transistors than in regular inversion-mode or accumulation-mode field effect transistors.
Abstract: The electric field perpendicular to the current flow is found to be significantly lower in junctionless transistors than in regular inversion-mode or accumulation-mode field-effect transistors. Since inversion channel mobility in metal-oxide-semionductor transistors is reduced by this electric field, the low field in junctionless transistor may give them an advantage in terms of current drive for nanometer-scale complementary metal-oxide semiconductor applications. This observation still applies when quantum confinement is present.
TL;DR: Recently, electric double layer transistors (EDLT), in which an ionic liquid or an electrolyte is used as a gate dielectric, have been the subject of intense research and rapidly increasing interest owing to the considerable amount of charge which can be provided by this technique.
Abstract: Field-effect transistors (FETs) are ubiquitous in our everyday life. Applying the fi eld-effect technique to new materials can lead not only to a modulation of their conductivity, but also to electrostatically driven phase transitions. [ 1–3 ] This method is particularly appealing for complex oxides, which exhibit a wide range of functional properties including metal-insulator (MI) transitions, colossal magnetoresistance and highT c superconductivity, all very sensitive to the level of electronic doping. The electric fi eld-effect approach seems thus to be a natural tool to try controlling and modifying reversibly the ground states of these materials. However, the required changes in carrier densities, which typically exceed 10 14 cm − 2 , [ 1 , 4 ] are diffi cult to induce with standard dielectrics. Recently, electric double layer transistors (EDLT), in which an ionic liquid or an electrolyte is used as a gate dielectric, have been the subject of intense research and rapidly increasing interest owing to the considerable amount of charge which can be provided by this technique. [ 5–7 ]
TL;DR: Analysis of experimental results regarding the electrical noise and cyclotron resonance suggests that the tight-binding approximation can be seen as a good starting point for understanding the electronic properties of graphene bilayer.
Abstract: We study, within the tight-binding approximation, the electronic properties of a graphene bilayer in the presence of an external electric field applied perpendicular to the system—a biased bilayer. The effect of the perpendicular electric field is included through a parallel plate capacitor model, with screening correction at the Hartree level. The full tight-binding description is compared with its four-band and two-band continuum approximations, and the four-band model is shown to always be a suitable approximation for the conditions realized in experiments. The model is applied to real biased bilayer devices, made out of either SiC or exfoliated graphene, and good agreement with experimental results is found, indicating that the model is capturing the key ingredients, and that a finite gap is effectively being controlled externally. Analysis of experimental results regarding the electrical noise and cyclotron resonance further suggests that the model can be seen as a good starting point for understanding the electronic properties of graphene bilayer. Also, we study the effect of electron–hole asymmetry terms, such as the second-nearest-neighbour hopping energies t' (in-plane) and γ4 (inter-layer), and the on-site energy Δ.
TL;DR: Electronic transport measurements on thin Bi2Se3 devices are reported and it is shown that the density of the surface states can be modulated via the electric field effect by using a top-gate with a high-k dielectric insulator.
Abstract: Electronic transport experiments involving the topologically protected states found at the surface of Bi2Se3 and other topological insulators require fine control over carrier density, which is challenging with existing bulk-doped material. Here we report on electronic transport measurements on thin (<100 nm) Bi2Se3 devices and show that the density of the surface states can be modulated via the electric field effect by using a top-gate with a high-k dielectric insulator. The conductance dependence on geometry, gate voltage, and temperature all indicate that transport is governed by parallel surface and bulk contributions. Moreover, the conductance dependence on top-gate voltage is ambipolar, consistent with tuning between electrons and hole carriers at the surface.
TL;DR: In this paper, a top-gate with a high-k dielectric insulator was used to modulate the surface states of Bi2Se3 and showed that the density of surface states can be modulated via the electric field effect.
Abstract: Electronic transport experiments involving the topologically protected states found at the surface of Bi2Se3 and other topological insulators require fine control over carrier density, which is challenging with existing bulk-doped material. Here we report on electronic transport measurements on thin (<100 nm) Bi2Se3 devices and show that the density of the surface states can be modulated via the electric field effect by using a top-gate with a high-k dielectric insulator. The conductance dependence on geometry, gate voltage, and temperature all indicate that transport is governed by parallel surface and bulk contributions. Moreover, the conductance dependence on top-gate voltage is ambipolar, consistent with tuning between electrons and hole carriers at the surface.
TL;DR: In this article, a voltage-induced perpendicular magnetic anisotropy change in an ultrathin FeCo layer was observed in an epitaxial magnetic tunnel junction (MTJ) structure.
Abstract: A voltage-induced perpendicular magnetic anisotropy change in an ultrathin FeCo layer was observed in an epitaxial magnetic tunnel junction (MTJ) structure. A spin-transfer induced ferromagnetic resonance measurement technique was used under various bias voltage applications to evaluate the anisotropy change. From the peak frequency shifts, we could estimate that a surface magnetic anisotropy change of 15 μJ/m2 was induced by an electric field application of 400 mV/nm in the MTJ with a 0.5 nm thick FeCo layer. The realization of voltage-induced anisotropy changes in an MTJ structure should have a large impact on the development of electric-field driven spintronic devices.
TL;DR: In this paper, the authors extended Krori and Barua's method to include pressure anisotropy and linear or nonlinear equations of state for self-gravitating, charged, anisotropic fluids and get even more flexibility in solving the Einstein-Maxwell equations.
Abstract: Ivanov pointed out substantial analytical difficulties associated with self-gravitating, static, isotropic fluid spheres when pressure explicitly depends on matter density. Simplifications achieved with the introduction of electric charge were noticed as well. We deal with self-gravitating, charged, anisotropic fluids and get even more flexibility in solving the Einstein-Maxwell equations. In order to discuss analytical solutions we extend Krori and Barua's method to include pressure anisotropy and linear or nonlinear equations of state. The field equations are reduced to a system of three algebraic equations for the anisotropic pressures as well as matter and electrostatic energy densities. Attention is paid to compact sources characterized by positive matter density and positive radial pressure. Arising solutions satisfy the energy conditions of general relativity. Spheres with vanishing net charge contain fluid elements with unbounded proper charge density located at the fluid-vacuum interface. Notably the electric force acting on these fluid elements is finite, although the acting electric field is zero. Net charges can be huge (${10}^{19}C$) and maximum electric field intensities are very large (${10}^{23}--{10}^{24}\text{ }\text{ }\mathrm{statvolt}/\mathrm{cm}$) even in the case of zero net charge. Inward-directed fluid forces caused by pressure anisotropy may allow equilibrium configurations with larger net charges and electric field intensities than those found in studies of charged isotropic fluids. Links of these results with charged strange quark stars as well as models of dark matter including massive charged particles are highlighted. The van der Waals equation of state leading to matter densities constrained by cubic polynomial equations is briefly considered. The fundamental question of stability is left open.
TL;DR: In this paper, a kinetic model was developed to describe the processes that contribute towards the fast transfer of electron energy into thermal energy under the conditions considered, taking into account previously suggested mechanisms to describe observations of fast heating in moderate (~102 Td) reduced electric fields.
Abstract: Observations of a shock wave propagating through a decaying plasma in the afterglow of an impulse high-voltage nanosecond discharge and of a surface dielectric barrier discharge in the nanosecond range were analysed to determine the electron power transferred into heat in air plasmas in high electric fields. It was shown that approximately half of the discharge power can go to heat for a short (~1 µs at atmospheric pressure) period of time when reduced electric fields are present at approximately 103 Td. A kinetic model was developed to describe the processes that contribute towards the fast transfer of electron energy into thermal energy under the conditions considered. This model takes into account previously suggested mechanisms to describe observations of fast heating in moderate (~102 Td) reduced electric fields and also considers the processes that become important in the presence of high electric fields. Calculations based on the developed model agree qualitatively with analyses of high-voltage nanosecond discharge observations.
TL;DR: Overall, this work confirms that imine addition chemistry can be used to build molecular wires long enough to probe the hopping transport regime, and finds that long ONI wires are less resistive than OPI wires.
Abstract: We report the electrical transport characteristics of conjugated oligonaphthalenefluoreneimine (ONI) wires having systematically varied lengths up to 10 nm. Using aryl imine addition chemistry, ONI wires were built from gold substrates by extending the conjugation length through imine linkages between highly conjugated building blocks of alternating naphthalenes and fluorenes. The resistance and current−voltage characteristics of ONI wires were measured as a function of molecular length, temperature, and electric field using conducting probe atomic force microscopy (CP-AFM). We have observed a transition in direct current (DC) transport from tunneling to hopping near 4 nm as previously established for oligophenyleneimine (OPI) wires. Furthermore, we have found that long ONI wires are less resistive than OPI wires. The single-wire conductivity of ONI wires is ∼1.8 ± 0.1 × 10−4 S/cm, a factor of ∼2 greater than that of OPI wires, and consistent with the lower transport activation energy (∼0.58 eV versus 0.6...
TL;DR: In this article, a pseudo-2D surface potential model for the double-gate tunnel field effect transistor (DG-TFET) is presented, where the depletion regions induced inside the source and drain are included in the solution and these regions become critical when scaling the device length.
Abstract: This paper presents a pseudo-2-D surface potential model for the double-gate tunnel field-effect transistor (DG-TFET). Analytical expressions are derived for the 2-D potential, electric field, and generation rate, and used to numerically extract the tunneling current. The model predicts the device characteristics for a large range of parameters and allows gaining insight on the device physics. The depletion regions induced inside the source and drain are included in the solution, and we show that these regions become critical when scaling the device length. The fringing field effect from the gates on these regions is also included. The validity of the model is tested for devices scaled to 10-nm length with SiO2 and high-? dielectrics by comparison to 2-D finite-element simulations.
TL;DR: Application of an electric field to a polarizable substrate provides a novel way to store hydrogen; once the applied electric field is removed, the stored H2 molecules can be easily released, thus making storage reversible with fast kinetics.
Abstract: Using density functional theory, we show that an applied electric field can substantially improve the hydrogen storage properties of polarizable substrates. This new concept is demonstrated by adsorbing a layer of hydrogen molecules on a number of nanomaterials. When one layer of H2 molecules is adsorbed on a BN sheet, the binding energy per H2 molecule increases from 0.03 eV/H2 in the field-free case to 0.14 eV/H2 in the presence of an electric field of 0.045 a.u. The corresponding gravimetric density of 7.5 wt% is consistent with the 6 wt% system target set by Department of Energy for 2010. The strength of the electric field can be reduced if the substrate is more polarizable. For example, a hydrogen adsorption energy of 0.14 eV/H2 can be achieved by applying an electric field of 0.03 a.u. on an AlN substrate, 0.006 a.u. on a silsesquioxane molecule, and 0.007 a.u. on a silsesquioxane sheet. Thus, application of an electric field to a polarizable substrate provides a novel way to store hydrogen; once the applied electric field is removed, the stored H2 molecules can be easily released, thus making storage reversible with fast kinetics. In addition, we show that materials with rich low-coordinated nonmetal anions are highly polarizable and can serve as a guide in the design of new hydrogen storage materials.
TL;DR: In this paper, the electric-field-induced strain behavior in (1 − x − y) NbO3 electroceramics has been studied using a combinatorial technique.
01 Nov 2010
TL;DR: In this paper, a top-gate with a high-k dielectric insulator was used to modulate the surface states of Bi2Se3 and showed that the density of surface states can be modulated via the electric field effect.
Abstract: Electronic transport experiments involving the topologically protected states found at the surface of Bi2Se3 and other topological insulators require fine control over carrier density, which is challenging with existing bulk-doped material. Here we report on electronic transport measurements on thin (<100 nm) Bi2Se3 devices and show that the density of the surface states can be modulated via the electric field effect by using a top-gate with a high-k dielectric insulator. The conductance dependence on geometry, gate voltage, and temperature all indicate that transport is governed by parallel surface and bulk contributions. Moreover, the conductance dependence on top-gate voltage is ambipolar, consistent with tuning between electrons and hole carriers at the surface.
TL;DR: In this paper, the longitudinal dependence of equatorial ionospheric electrodynamic perturbations during sudden stratospheric warmings was studied using plasma drift and magnetic field measurements during the 2001-2009 December solstices.
Abstract: [1] We have used plasma drift and magnetic field measurements during the 2001–2009 December solstices to study, for the first time, the longitudinal dependence of equatorial ionospheric electrodynamic perturbations during sudden stratospheric warmings. Jicamarca radar measurements during these events show large dayside downward drift (westward electric field) perturbations followed by large morning upward and afternoon downward drifts that systematically shift to later local times. Ground-based magnetometer measurements in the American, Indian, and Pacific equatorial regions show strongly enhanced electrojet currents in the morning sector and large reversed currents (i.e., counterelectrojets) in the afternoon sector with onsets near new and full moons during northern winter warming periods. CHAMP satellite and ground-based magnetic field observations indicate that the onset of these equatorial afternoon counterelectrojets is longitude dependent. Our results indicate that these large electrodynamic perturbations during stratospheric warming periods are due to strongly enhanced semidiurnal lunar wave effects. The results of our study can be used for forecasting the occurrence and evolution of these electrodynamic perturbations during arctic winter warmings.
TL;DR: This work presents a method for measuring the effect of an externally applied electric field on the absorption of dye monolayers adsorbed on flat TiO(2) substrates, and demonstrates that the electric field across the dye molecules changes upon illumination.
Abstract: The dye-sensitized solar cell (DSC) challenges conventional photovoltaics with its potential for low-cost production and its flexibility in terms of color and design Transient absorption spectrosco ...
TL;DR: In this paper, a survey of 175 magnetotail passes resulted in a sample of 33 correlated field and flow reversals, and the average peak Hall magnetic and electric field was found to be 0.39 ± 0.16.
Abstract: [1] Magnetic reconnection plays a key role in the circulation of plasma through the Earth's magnetosphere. As such, the Earth's magnetotail is an excellent natural laboratory for the study of reconnection and in particular the diffusion region. To address important questions concerning observational occurrence rates and average properties, the Cluster data set from 2001–2005 has been systematically examined for encounters with reconnection X lines and ion diffusion regions in the Earth's magnetotail. This survey of 175 magnetotail passes resulted in a sample of 33 correlated field and flow reversals. Eighteen events exhibited electric and magnetic field perturbations qualitatively consistent with the predictions of antiparallel Hall reconnection and could be identified as diffusion region encounters. The magnitudes of both the Hall magnetic and electric field were found to vary from event to event. When normalized against the inflow magnetic field and the current sheet number density the average peak Hall magnetic field was found to be 0.39 ± 0.16, the average peak Hall electric field was found to be 0.33 ± 0.18, and the average out of plane (reconnection) electric field was found to be ∼0.04. Good quantitative agreement was found between these results and a large, appropriately renormalized particle-in-cell simulation of reconnection. In future missions, the magnitude of the total DC electric field may be a useful tool for automatically identifying ion diffusion region encounters.
TL;DR: In this article, polyvinylidene fluoride-co-hexafluoropropylene [P(VDF−HFP)] films with different crystal orientations were fabricated.
Abstract: By using different preparation and processing methods, poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF−HFP)] films with different crystal orientations were fabricated. Anisotropic dielectric properties and different electric energy storages were observed in these films. When the PVDF crystals in a film oriented with their c-axes perpendicular to the applied electric field, they exhibited large polarizability because the CF2 dipole moments were randomly distributed in a plane parallel to the electric field. As a result, high dielectric constant and high electric energy density were achieved. On the contrary, when the crystal c-axes in a film oriented parallel to the electric field (or the CF2 dipole moments perpendicular to the electric field), polarization became difficult. Consequently, low dielectric constant and low electric energy density resulted. The anisotropic polarizability was also displayed at high electric fields as evidenced by the difference in the remnant/maximum polarization and th...
TL;DR: In this paper, a technique to control the energetic splitting of two quantum states using a vertical electric field, facilitating the observation of coherent coupling between them, was described, leading to the generation of entangled photon pairs.
Abstract: The signature of coherent coupling between two quantum states is an anticrossing in their energies as one is swept through the other. In single semiconductor quantum dots containing an electron–hole pair the eigenstates form a two-level system that can be used to demonstrate quantum effects in the solid state, but in all previous work these states were independent. Here we describe a technique to control the energetic splitting of these states using a vertical electric field, facilitating the observation of coherent coupling between them. Near the minimum splitting the eigenstates rotate in the plane of the sample, being orientated at 45° when the splitting is smallest. Using this system we show direct control over the exciton states in one quantum dot, leading to the generation of entangled photon pairs.
TL;DR: In this paper, thin films of TiN were sputterdeposited onto Si and sapphire wafers with and without SiN buffer layers, and internal quality factor measurements were taken at millikelvin temperatures in both the many photon and single photon limits, respectively.
Abstract: Thin films of TiN were sputter-deposited onto Si and sapphire wafers with and without SiN buffer layers. The films were fabricated into rf coplanar waveguide resonators, and internal quality factor measurements were taken at millikelvin temperatures in both the many photon and single photon limits, i.e., high and low electric field regimes, respectively. At high field, we found the highest internal quality factors (∼107) were measured for TiN with predominantly a (200)-TiN orientation. The (200)-TiN is favored for growth at high temperature on either bare Si or SiN buffer layers. However, growth on bare sapphire or Si(100) at low temperature resulted in primarily a (111)-TiN orientation. Ellipsometry and Auger measurements indicate that the (200)-TiN growth on the bare Si substrates is correlated with the formation of a thin, ≈2 nm, layer of SiN during the predeposition procedure. On these surfaces we found a significant increase of Qi for both high and low electric field regimes.