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Showing papers on "Electric field published in 2017"


Journal ArticleDOI
TL;DR: It is demonstrated that an in-plane effective magnetic field can be induced by an electric field without breaking the symmetry of the structure of the thin film, and the deterministic magnetization switching in a hybrid ferromagnetic/ferroelectric structure with Pt/Co/Ni/ Co/Pt layers on PMN-PT substrate is realized.
Abstract: All-electrical and programmable manipulations of ferromagnetic bits are highly pursued for the aim of high integration and low energy consumption in modern information technology. Methods based on the spin-orbit torque switching in heavy metal/ferromagnet structures have been proposed with magnetic field, and are heading toward deterministic switching without external magnetic field. Here we demonstrate that an in-plane effective magnetic field can be induced by an electric field without breaking the symmetry of the structure of the thin film, and realize the deterministic magnetization switching in a hybrid ferromagnetic/ferroelectric structure with Pt/Co/Ni/Co/Pt layers on PMN-PT substrate. The effective magnetic field can be reversed by changing the direction of the applied electric field on the PMN-PT substrate, which fully replaces the controllability function of the external magnetic field. The electric field is found to generate an additional spin-orbit torque on the CoNiCo magnets, which is confirmed by macrospin calculations and micromagnetic simulations.

398 citations


Journal ArticleDOI
TL;DR: Hall thrusters as discussed by the authors are very efficient and competitive electric propulsion devices for satellites and are currently in use in a number of telecommunications and government spacecraft, with specific impulse values between 1000 and 3000's.
Abstract: Hall thrusters are very efficient and competitive electric propulsion devices for satellites and are currently in use in a number of telecommunications and government spacecraft. Their power spans from 100 W to 20 kW, with thrust between a few mN and 1 N and specific impulse values between 1000 and 3000 s. The basic idea of Hall thrusters consists in generating a large local electric field in a plasma by using a transverse magnetic field to reduce the electron conductivity. This electric field can extract positive ions from the plasma and accelerate them to high velocity without extracting grids, providing the thrust. These principles are simple in appearance but the physics of Hall thrusters is very intricate and non-linear because of the complex electron transport across the magnetic field and its coupling with the electric field and the neutral atom density. This paper describes the basic physics of Hall thrusters and gives a (non-exhaustive) summary of the research efforts that have been devoted to th...

326 citations


Journal ArticleDOI
20 Oct 2017-Science
TL;DR: Permeation measurements under a direct-current E-field poling of 500 volts per millimeter showed reversibly controlled switching of the ZIF-8 into polar polymorphs, which was confirmed by x-ray diffraction and ab initio calculations, and a defibrillation of the different lattice motions.
Abstract: Gas transport through metal-organic framework membranes (MOFs) was switched in situ by applying an external electric field (E-field). The switching of gas permeation upon E-field polarization could be explained by the structural transformation of the zeolitic imidazolate framework ZIF-8 into polymorphs with more rigid lattices. Permeation measurements under a direct-current E-field poling of 500 volts per millimeter showed reversibly controlled switching of the ZIF-8 into polar polymorphs, which was confirmed by x-ray diffraction and ab initio calculations. The stiffening of the lattice causes a reduction in gas transport through the membrane and sharpens the molecular sieving capability. Dielectric spectroscopy, polarization, and deuterium nuclear magnetic resonance studies revealed low-frequency resonances of ZIF-8 that we attribute to lattice flexibility and linker movement. Upon E-field polarization, we observed a defibrillation of the different lattice motions.

304 citations


Journal ArticleDOI
TL;DR: In this paper, the direction of the electric field generated by the tip of a scanning tunnelling microscope can be exploited to locally and reversibly switch between a ferromagnetic state and a skyrmion.
Abstract: The electric field generated by the tip of a scanning tunnelling microscope can be exploited to locally and reversibly switch between a ferromagnetic state and a skyrmion. Controlling magnetism with electric fields is a key challenge to develop future energy-efficient devices1,2. The present magnetic information technology is mainly based on writing processes requiring either local magnetic fields or spin torques, but it has also been demonstrated that magnetic properties can be altered on the application of electric fields2,3,4,5. This has been ascribed to changes in magnetocrystalline anisotropy caused by spin-dependent screening and modifications of the band structure6,7,8, changes in atom positions5,9,10 or differences in hybridization with an adjacent oxide layer4,11. However, the switching between states related by time reversal, for example magnetization up and down as used in the present technology, is not straightforward because the electric field does not break time-reversal symmetry. Several workarounds have been applied to toggle between bistable magnetic states with electric fields12,13, including changes of material composition as a result of electric fields14. Here we demonstrate that local electric fields can be used to switch reversibly between a magnetic skyrmion15,16 and the ferromagnetic state. These two states are topologically inequivalent, and we find that the direction of the electric field directly determines the final state. This observation establishes the possibility to combine electric-field writing with the recently envisaged skyrmion racetrack-type memories17,18.

294 citations


Journal ArticleDOI
TL;DR: In this article, the impact of Coulomb force on nanofluid forced convective heat transfer is examined using Fe3O4-Ethylene glycol nan ofluid.

268 citations


Journal ArticleDOI
TL;DR: In this article, the authors used the observed properties of fast radio bursts (FRBs) and a number of general physical considerations to provide a broad-brush model for the physical properties of FRB sources and the radiation mechanism.
Abstract: We use the observed properties of fast radio bursts (FRBs) and a number of general physical considerations to provide a broad-brush model for the physical properties of FRB sources and the radiation mechanism. We show that the magnetic field in the source region should be at least 10^{14} Gauss. This strong field is required to ensure that the electrons have sufficiently high ground state Landau energy so that particle collisions, instabilities, and strong electric and magnetic fields associated with the FRB radiation do not perturb electrons' motion in the direction transverse to the magnetic field and destroy their coherent motion; coherence is required by the high observed brightness temperature of FRB radiation. The electric field in the source region required to sustain particle motion for a wave period is estimated to be of order 10^{11} esu. These requirements suggest that FRBs are produced near the surface of magnetars perhaps via forced reconnection of magnetic fields to produce episodic, repeated, outbursts. The beaming-corrected energy release in these bursts is estimated to be ~10^{36} ergs, whereas the total energy in the magnetic field is at least ~10^{45} ergs. We provide a number of predictions for this model which can be tested by future observations. One of which is that short duration FRB-like bursts should exist at much higher frequencies, possibly up to optical.

254 citations


Journal ArticleDOI
TL;DR: It is shown that the formation/annihilation of iodine vacancies (VI) in MAPbI3 films, driven by electric fields and light illumination, can induce pronounced resistive switching effects and provide guidance toward improved stability and performance of perovskite-based optoelectronic systems.
Abstract: Organic–inorganic halide perovskite (OHP) materials, for example, CH3NH3PbI3 (MAPbI3), have attracted significant interest for applications such as solar cells, photodectors, light-emitting diodes, and lasers. Previous studies have shown that charged defects can migrate in perovskites under an electric field and/or light illumination, potentially preventing these devices from practical applications. Understanding and control of the defect generation and movement will not only lead to more stable devices but also new device concepts. Here, it is shown that the formation/annihilation of iodine vacancies (VI's) in MAPbI3 films, driven by electric fields and light illumination, can induce pronounced resistive switching effects. Due to a low diffusion energy barrier (≈0.17 eV), the VI's can readily drift under an electric field, and spontaneously diffuse with a concentration gradient. It is shown that the VI diffusion process can be suppressed by controlling the affinity of the contact electrode material to I− ions, or by light illumination. An electrical-write and optical-erase memory element is further demonstrated by coupling ion migration with electric fields and light illumination. These results provide guidance toward improved stability and performance of perovskite-based optoelectronic systems, and can lead to the development of solid-state devices that couple ionics, electronics, and optics.

244 citations


Journal ArticleDOI
Hong Zhou1, Mengwei Si1, Sami Alghamdi1, Gang Qiu1, Lingming Yang1, Peide D. Ye1 
TL;DR: In this article, the authors report on high performance depletion/enhancement-mode GOOI field effect transistors (FETs) with record high drain currents of 600/450 mA/mm, which is nearly one order of magnitude higher than any other reported drain currents.
Abstract: In this letter, we report on high-performance depletion/enhancement-mode $\beta $ -Ga2O3 on insulator (GOOI) field-effect transistors (FETs) with record high drain currents ( $\text{I}_{\mathrm {\sf D}}$ ) of 600/450 mA/mm, which are nearly one order of magnitude higher than any other reported $\text{I}_{\mathrm {\sf D}}$ values. The threshold voltage ( $\text{V}_{\mathrm {\sf T}}$ ) can be modulated by varying the thickness of the $\beta $ -Ga2O3 films and the E-mode GOOI FET can be simply achieved by shrinking the $\beta $ -Ga2O3 film thickness. Benefiting from the good interface between $\beta $ -Ga2O3 and SiO2 and wide bandgap of $\beta $ -Ga2O3, a negligible transfer characteristic hysteresis, high $\text{I}_{\mathrm {\sf D}}$ ON/OFF ratio of $10^{10}$ , and low subthreshold swing of 140 mV/decade for a 300-nm-thick SiO2 are observed. E-mode GOOI FET with source to drain spacing of 0.9- $\sf \mu \text{m}$ demonstrates a breakdown voltage of 185 V and an average electric field (E) of 2 MV/cm, showing the great promise of GOOI FET for future power devices.

236 citations


Journal ArticleDOI
01 Sep 2017-Small
TL;DR: These localized fields are proved to effectively promote the detection ability of 2DPDs by suppressing background noise, enhancing optical absorption, improving electron-hole separation efficiency, amplifying photoelectric gain and/or extending the detection range.
Abstract: Two-dimensional (2D) materials have drawn tremendous attention in recent years. Being atomically thin, stacked with van der Waals force and free of surface chemical dangling bonds, 2D materials exhibit several distinct physical properties. To date, 2D materials include graphene, transition metal dichalcogenides (TMDS), black phosphorus, black P(1-x) Asx , boron nitride (BN) and so forth. Owing to their various bandgaps, 2D materials have been utilized for photonics and optoelectronics. Photodetectors based on 2D materials with different structures and detection mechanisms have been established and present excellent performance. In this Review, localized field enhanced 2D material photodetectors (2DPDs) are introduced with sensitivity over the spectrum from ultraviolet, visible to infrared in the sight of the influence of device structure on photodetector performance instead of directly illustrating the detection mechanisms. Six types of localized fields are summarized. They are: ferroelectric field, photogating electric field, floating gate induced electrostatic field, interlayer built-in field, localized optical field, and photo-induced temperature gradient field, respectively. These localized fields are proved to effectively promote the detection ability of 2DPDs by suppressing background noise, enhancing optical absorption, improving electron-hole separation efficiency, amplifying photoelectric gain and/or extending the detection range.

235 citations


Journal ArticleDOI
Qibin Yuan1, Fang-Zhou Yao1, Yifei Wang1, Rong Ma1, Hong Wang1 
TL;DR: A relaxor ferroelectric ceramic for high energy storage applications based on 0.9BaTiO3-0.1BZZ was successfully fabricated via a conventional solid-state method.
Abstract: A relaxor ferroelectric ceramic for high energy storage applications based on 0.9BaTiO3–0.1Bi(Zn0.5Zr0.5)O3 (0.9BT–0.1BZZ) was successfully fabricated via a conventional solid-state method. The sintered samples have a perovskite structure with a pseudocubic phase, showing a moderate dielectric constant (500–2000), low dielectric loss (tan δ < 0.15) and highly diffusive and dispersive relaxor-like behavior. The weak dielectric nonlinearity exhibits a dielectric constant change of ∼10% as the bias electric field increases from 0 kV cm−1 to 40 kV cm−1. Extra slim polarization–electric field loops accompanying the slow decrease of breakdown strength from 266.5 kV cm−1 to 217.7 kV cm−1 are observed in a measured temperature range of 30–150 °C. A maximum energy density of 2.46 J cm−3 was obtained at the electric field of 264 kV cm−1 close to the breakdown strength at ambient temperature. Temperature stability of both energy density and energy efficiency exists in a wide temperature range, which makes BT–BZZ ceramics promising candidates for high power electric applications.

213 citations


Journal ArticleDOI
TL;DR: In this paper, the influence of Coulomb forces on Fe3O4-H2O nanofluid thermal improvement in a cavity with moving wall is examined and the final formulas are solved via Control Volume based Finite Element Method.

Journal ArticleDOI
TL;DR: The European Space Agency's three Swarm satellites were launched on November 22, 2013 into nearly polar, circular orbits, eventually reaching altitudes of 460 km (Swarm A and C) and 510 km(Swarm B). Swarm's multi-year mission is to make precision, multi-point measurements of low-frequency magnetic and electric fields in Earth's ionosphere for the purpose of characterizing magnetic fields generated both inside and external to the Earth, along with other plasma parameters associated with electric current systems in the ionosphere and magnetosphere.
Abstract: The European Space Agency's three Swarm satellites were launched on November 22, 2013 into nearly-polar, circular orbits, eventually reaching altitudes of 460 km (Swarm A and C) and 510 km (Swarm B). Swarm's multi-year mission is to make precision, multi-point measurements of low-frequency magnetic and electric fields in Earth's ionosphere for the purpose of characterizing magnetic fields generated both inside and external to the Earth, along with the electric fields and other plasma parameters associated with electric current systems in the ionosphere and magnetosphere. Electric fields perpendicular to the magnetic field B→ are determined through ion drift velocity v→i and magnetic field measurements via the relation E→⊥=−v→i×B→. Ion drift is derived from two-dimensional images of low-energy ion distribution functions provided by two Thermal Ion Imager (TII) sensors viewing in the horizontal and vertical planes; v→i is corrected for spacecraft potential as determined by two Langmuir probes (LPs) which also measure plasma density ne and electron temperature Te. The TII sensors use a microchannel-plate-intensified phosphor screen imaged by a charge-coupled device to generate high-resolution distribution images ( 66x40 pixels) at a rate of 16 s−1. Images are partially processed on board and further on the ground to generate calibrated data products at a rate of 2 s−1; these include v→i, E→⊥, and ion temperature Ti in addition to electron temperature Te and plasma density ne from the LPs.

Journal ArticleDOI
TL;DR: A new photonic structure is produced from cellulose nanocrystal iridescent films reflecting both right and left circularly polarized light that is reversibly tuned by the application of an electric field or a temperature variation.
Abstract: A new photonic structure is produced from cellulose nanocrystal iridescent films reflecting both right and left circularly polarized light. Micrometer-scale planar gaps perpendicular to the films' cross-section between two different left-handed films' cholesteric domains are impregnated with a nematic liquid crystal. This photonic feature is reversibly tuned by the application of an electric field or a temperature variation.

Journal ArticleDOI
TL;DR: Home-built spatially resolved surface photovoltage spectroscopy (SRSPS) supplies a direct evidence for the vectorial charge transfer of photogenerated electrons from rutile to anatase, and the tunable anatase nanoparticle sizes in TiO2 phase junction leads to high surface photvoltage (SPV).
Abstract: Phase junction is often recognized as an effective strategy to achieve efficient charge separation in photocatalysis and photochemistry. As a crucial factor to determine the photogenerated charges dynamics, there is an increasingly hot debate about the energy band alignment across the interface of phase junction. Herein, we reported the direct measurement of the surface potential profile over the interface of TiO2 phase junction. A built-in electric field up to 1 kV/cm from rutile to anatase nanoparticle was detected by Kelvin Probe Force Microscopy (KPFM). Home-built spatially resolved surface photovoltage spectroscopy (SRSPS) supplies a direct evidence for the vectorial charge transfer of photogenerated electrons from rutile to anatase. Moreover, the tunable anatase nanoparticle sizes in TiO2 phase junction leads to high surface photovoltage (SPV) by creating completely depleted space charge region (SCR) and enhancing the charge separation efficiency. The results provide a strong basis for understanding...

Journal ArticleDOI
TL;DR: In this article, the authors reported experimental evidence of strong radiation reaction, in an all-optical experiment, during the propagation of highly relativistic electrons (maximum energy exceeding 2 GeV) through the field of an ultra-intense laser (peak intensity of $4\times10^{20}$ W/cm$^2$).
Abstract: The description of the dynamics of an electron in an external electromagnetic field of arbitrary intensity is one of the most fundamental outstanding problems in electrodynamics. Remarkably, to date there is no unanimously accepted theoretical solution for ultra-high intensities and little or no experimental data. The basic challenge is the inclusion of the self-interaction of the electron with the field emitted by the electron itself - the so-called radiation reaction force. We report here on the experimental evidence of strong radiation reaction, in an all-optical experiment, during the propagation of highly relativistic electrons (maximum energy exceeding 2 GeV) through the field of an ultra-intense laser (peak intensity of $4\times10^{20}$ W/cm$^2$). In their own rest frame, the highest energy electrons experience an electric field as high as one quarter of the critical field of quantum electrodynamics and are seen to lose up to 30% of their kinetic energy during the propagation through the laser field. The experimental data show signatures of quantum effects in the electron dynamics in the external laser field, potentially showing departures from the constant cross field approximation.

Journal ArticleDOI
Jieun Lee1, Zefang Wang1, Hongchao Xie1, Kin Fai Mak1, Jie Shan1 
TL;DR: A new form of the ME effect based on the valley DOF in two-dimensional Dirac materials is reported, demonstrating the pure electrical generation of valley magnetization in this material and its direct imaging by Kerr rotation microscopy.
Abstract: The magnetoelectric (ME) effect, the phenomenon of inducing magnetization by application of an electric field or vice versa, holds great promise for magnetic sensing and switching applications. Studies of the ME effect have so far focused on the control of the electron spin degree of freedom (DOF) in materials such as multiferroics and conventional semiconductors. Here, we report a new form of the ME effect based on the valley DOF in two-dimensional Dirac materials. By breaking the three-fold rotational symmetry in single-layer MoS 2 via a uniaxial stress, we have demonstrated the pure electrical generation of valley magnetization in this material, and its direct imaging by Kerr rotation microscopy. The observed out-of-plane magnetization is independent of in-plane magnetic field, linearly proportional to the in-plane current density, and optimized when the current is orthogonal to the strain-induced piezoelectric field. These results are fully consistent with a theoretical model of valley magnetoelectricity driven by Berry curvature effects. Furthermore, the effect persists at room temperature, opening possibilities for practical valleytronic devices.

Journal ArticleDOI
TL;DR: In high external magnetic fields, a universal Faraday rotation angle equal to the fine structure constant α=e2/2hc is observed when a linearly polarized THz radiation of a certain frequency passes through the two surfaces of a strained HgTe 3D TI.
Abstract: The electrodynamics of topological insulators (TIs) is described by modified Maxwell’s equations, which contain additional terms that couple an electric field to a magnetization and a magnetic field to a polarization of the medium, such that the coupling coefficient is quantized in odd multiples of α/4π per surface. Here we report on the observation of this so-called topological magnetoelectric effect. We use monochromatic terahertz (THz) spectroscopy of TI structures equipped with a semitransparent gate to selectively address surface states. In high external magnetic fields, we observe a universal Faraday rotation angle equal to the fine structure constant α=e2/2 hc (in SI units) when a linearly polarized THz radiation of a certain frequency passes through the two surfaces of a strained HgTe 3D TI. These experiments give insight into axion electrodynamics of TIs and may potentially be used for a metrological definition of the three basic physical constants. The electrodynamics of topological insulators has been predicted to show a new magnetoelectric term, but this hasn’t been observed. Here, Dziomet al. observe a universal Faraday rotation angle equal to the fine structure constant, evidencing the so-called topological magnetoelectric effect.

Journal ArticleDOI
TL;DR: In this paper, a new physical-assisted casting method was developed to tune the orientation of elongated BaTiO3 nanowires in a P(VDF-CTFE) matrix.
Abstract: In practical application, new dielectric capacitors with greater energy density at lower operating voltage will be promising candidates for high-performance electrical devices. Theoretically, it is possible to achieve large electric polarization at a low electric field via embedding aligned ferroelectric nanowires in a polymer matrix, which could release high energy density. However, in terms of practice, the design of nanocomposites with aligned nanowires poses a great technical challenge. Here, a new physical-assisted casting method was developed to tune the orientation of elongated BaTiO3 nanowires in a P(VDF-CTFE) matrix. In the Z-aligned nanocomposites, a large (Dmax − Pr) value of 9.93 μC cm−2 can be induced at a low electric field of 2400 kV cm−1 by aligning 3 vol% ferroelectric BaTiO3 nanowires in the poling direction. Compared with X–Y-aligned nanocomposites even at a high electric field of 3400 kV cm−1, the Z-aligned nanocomposites could exhibit simultaneously an enhanced energy density of 10.8 J cm−3 and a discharge efficiency of 61.4% at 2400 kV cm−1. To the best of our knowledge, among ferroelectric nanocomposites, this is the highest energy density ever obtained at such a low electric field. This work is of critical significance in making dielectric nanocomposites viable for energy storage devices in current electrical and electronic applications.

Journal ArticleDOI
TL;DR: In this article, it was shown that the effect of charm quarks (CQs) compared to light quarks is due to a combination of several favorable conditions for CQs, such as τ f ≃ 0.1 fm / c, which is comparable to the time scale when B → attains its maximum value, and the kinetic relaxation time of CQ, which helps the CQ to retain the initial kick picked up from the electromagnetic field in the transverse direction.

Journal ArticleDOI
TL;DR: In this article, it was shown that rapid heating can accelerate sintering by over 2 orders of magnitude compared with heating to the same temperature at conventional rates, even without the application of an electric field.
Abstract: It has recently been reported that ceramics can be sintered in a few seconds with the aid of an electric field (“flash sintering”). This investigation tests the possibility that the accelerated sintering is a consequence of the rapid heating rate involved rather than a direct effect of the electric field on mass transport. The sintering of 3YSZ powder compacts at a temperature of ∼1300 °C was compared (i) in flash sintering, (ii) with rapid heating rates produced without the application of an electric field, and (iii) with conventional heating rates. The results show that rapid heating can accelerate sintering by over 2 orders of magnitude compared with heating to the same temperature at conventional rates, even without the application of an electric field. It is concluded that the rapid densification in flash sintering of 3YSZ is at least partly a consequence of the rapid heating involved. Possible explanations are discussed.

Journal ArticleDOI
TL;DR: In this paper, the authors analyzed heat and mass transfer with the transverse magnetic field on peristaltic motion of two-phase flow (particle-fluid suspension) through a planar channel.

Journal ArticleDOI
TL;DR: In this paper, an electric-field-assisted multicolor printing is reported based on electrically responsive and photocurable colloidal photonic crystal, which is prepared by supersaturation-induced self-assembly of SiO2 particles in the mixture of propylene carbonate (PC) and trimethylolpropane ethoxylate triacrylate (ETPTA).
Abstract: Efficient and large scale printing of photonic crystal patterns with multicolor, multigrayscale, and fine resolution is highly desired due to its application in smart prints, sensors, and photonic devices. Here, an electric-field-assisted multicolor printing is reported based on electrically responsive and photocurable colloidal photonic crystal, which is prepared by supersaturation-induced self-assembly of SiO2 particles in the mixture of propylene carbonate (PC) and trimethylolpropane ethoxylate triacrylate (ETPTA). This colloidal crystal suspension, named as E-ink, has tunable structural color, controllable grayscale, and instantly fixable characteristics at the same time because the SiO2/ETPTA-PC photonic crystal has metastable and reversible assembly as well as polymerizable features. Lithographical printing with photomask and maskless pixel printing techniques are developed respectively to efficiently prepare multicolor and high-resolution photonic patterns using a single-component E-ink.

Journal ArticleDOI
Chuanyang Li1, Jun Hu1, Lin Chuanjie1, Boya Zhang1, Guixin Zhang1, Jinliang He1 
TL;DR: In this paper, the effect of direct fluorination on surface charge migration and flashover voltage was verified, and it was shown that the surface charge decay of epoxy-based model insulators is a slow process, but the decay rate increases when an outer dc electric field is applied.
Abstract: Epoxy-based model insulators were manufactured and fluorinated under a F2/N2 mixture (12.5% F2) at 50 °C and 0.1 MPa for 15 min and 60 min. Surface charge accumulation and decay behavior were studied with and without dc voltage application. The effect of direct fluorination on surface charge migration as well as on flashover voltage was verified. The obtained results show that the charge decay of epoxy-based insulators is a slow process, but the decay rate increases when an outer dc electric field is applied. The surface charge distribution is changed when a streamer is triggered on the insulator surface. The existence of heteropolarity surface charges can decrease the dc surface flashover voltage to some extent, while the surface flashover voltage is almost unchanged when charges of the same polarity accumulate on the insulator surface. The short time fluorinated insulator can modify the surface resistivity, and the rate of surface charge dissipation is greatly increased under a dc electric field.

Journal ArticleDOI
TL;DR: In this paper, the relationship between the Rabi frequency (ΩRF) related to the applied electric field and Autler-Townes (AT) splitting, when performing atom-based radiofrequency (RF) electric (E) field strength measurements using Rydberg states and electromagnetically induced transparency (EIT) in an atomic vapor, was investigated.
Abstract: We investigate the relationship between the Rabi frequency (ΩRF, related to the applied electric field) and Autler-Townes (AT) splitting, when performing atom-based radio-frequency (RF) electric (E) field strength measurements using Rydberg states and electromagnetically induced transparency (EIT) in an atomic vapor. The AT splitting satisfies, under certain conditions, a well-defined linear relationship with the applied RF field amplitude. The EIT/AT-based E-field measurement approach derived from these principles is currently being investigated by several groups around the world as a means to develop a new SI-traceable RF E-field measurement technique. We establish conditions under which the measured AT-splitting is an approximately linear function of the RF electric field. A quantitative description of systematic deviations from the linear relationship is key to exploiting EIT/AT-based atomic-vapor spectroscopy for SI-traceable field measurement. We show that the linear relationship is valid and can be...

Journal ArticleDOI
TL;DR: This work demonstrates magnetization switching of ferromagnetic thin layers that is induced solely by adsorption of chiral molecules, and presents a simple low-power magnetization mechanism when operating at ambient conditions.
Abstract: Ferromagnets are commonly magnetized by either external magnetic fields or spin polarized currents. The manipulation of magnetization by spin-current occurs through the spin-transfer-torque effect, which is applied, for example, in modern magnetoresistive random access memory. However, the current density required for the spin-transfer torque is of the order of 1 × 106 A·cm−2, or about 1 × 1025 electrons s−1 cm−2. This relatively high current density significantly affects the devices’ structure and performance. Here we demonstrate magnetization switching of ferromagnetic thin layers that is induced solely by adsorption of chiral molecules. In this case, about 1013 electrons per cm2 are sufficient to induce magnetization reversal. The direction of the magnetization depends on the handedness of the adsorbed chiral molecules. Local magnetization switching is achieved by adsorbing a chiral self-assembled molecular monolayer on a gold-coated ferromagnetic layer with perpendicular magnetic anisotropy. These results present a simple low-power magnetization mechanism when operating at ambient conditions. Spin manipulation in memory devices typically requires large electrical currents, limiting performance. Here the authors demonstrate magnetization switching in ferromagnetic films by depositing chiral molecules, making use of a proximity effect without needing magnetic or electric fields.

Journal ArticleDOI
TL;DR: Freestanding, single-component dielectric actuators are designed based on bottlebrush elastomers that enable giant reversible strokes at relatively low electric fields and altogether avoid preactuation mechanical manipulation.
Abstract: Freestanding, single-component dielectric actuators are designed based on bottlebrush elastomers that enable giant reversible strokes at relatively low electric fields and altogether avoid preactuation mechanical manipulation. This materials design platform allows for independent tuning of actuator rigidity and elasticity over broad ranges without changing chemical composition, which opens new opportunities in soft-matter robotics.

Journal ArticleDOI
TL;DR: Different from a typical ferroelectric whose electric polarization is easily saturated, these Ba(Zr0.2,Ti0.8)O3 films display a much delayed saturation of the electric polarization, leading to drastically improved recyclable energy densities and may enable broader applications of dielectric capacitors in energy storage, conditioning, and conversion.
Abstract: Dielectric capacitors have the highest charge/discharge speed among all electrical energy devices, but lag behind in energy density. Here we report dielectric ultracapacitors based on ferroelectric films of Ba(Zr0.2,Ti0.8)O3 which display high-energy densities (up to 166 J cm–3) and efficiencies (up to 96%). Different from a typical ferroelectric whose electric polarization is easily saturated, these Ba(Zr0.2,Ti0.8)O3 films display a much delayed saturation of the electric polarization, which increases continuously from nearly zero at remnant in a multipolar state, to a large value under the maximum electric field, leading to drastically improved recyclable energy densities. This is achieved by the creation of an adaptive nano-domain structure in these perovskite films via phase engineering and strain tuning. The lead-free Ba(Zr0.2,Ti0.8)O3 films also show excellent dielectric and energy storage performance over a broad frequency and temperature range. These findings may enable broader applications of dielectric capacitors in energy storage, conditioning, and conversion.

Journal ArticleDOI
TL;DR: The real-space imaging of the (projected) atomic electric field distribution inside single Au atoms is demonstrated, using sub-Å spatial resolution STEM combined with a high-speed segmented detector.
Abstract: In scanning transmission electron microscopy (STEM), single atoms can be imaged by detecting electrons scattered through high angles using post-specimen, annular-type detectors. Recently, it has been shown that the atomic-scale electric field of both the positive atomic nuclei and the surrounding negative electrons within crystalline materials can be probed by atomic-resolution differential phase contrast STEM. Here we demonstrate the real-space imaging of the (projected) atomic electric field distribution inside single Au atoms, using sub-A spatial resolution STEM combined with a high-speed segmented detector. We directly visualize that the electric field distribution (blurred by the sub-A size electron probe) drastically changes within the single Au atom in a shape that relates to the spatial variation of total charge density within the atom. Atomic-resolution electric field mapping with single-atom sensitivity enables us to examine their detailed internal and boundary structures.

Journal ArticleDOI
TL;DR: In this paper, the photoemission from an array of plasmonic nanoparticles is shown to be controlled by the light's electric field in the strong-field regime, where the light is usually driven by the energy of the illuminating laser pulses.
Abstract: Photoemission is usually driven by the energy of the illuminating laser pulses, but in the strong-field regime, the photoemission from an array of plasmonic nanoparticles is shown to be controlled by the light’s electric field.

Proceedings ArticleDOI
02 May 2017
TL;DR: It is shown that Electrick can enable new interactive opportunities on a diverse set of objects and surfaces that were previously static, and is compatible with commonplace manufacturing methods, such as spray/brush coating, vacuum forming, and casting/molding enabling a wide range of possible uses and outputs.
Abstract: Current touch input technologies are best suited for small and flat applications, such as smartphones, tablets and kiosks. In general, they are too expensive to scale to large surfaces, such as walls and furniture, and cannot provide input on objects having irregular and complex geometries, such as tools and toys. We introduce Electrick, a low-cost and versatile sensing technique that enables touch input on a wide variety of objects and surfaces, whether small or large, flat or irregular. This is achieved by using electric field tomography in concert with an electrically conductive material, which can be easily and cheaply added to objects and surfaces. We show that our technique is compatible with commonplace manufacturing methods, such as spray/brush coating, vacuum forming, and casting/molding enabling a wide range of possible uses and outputs. Our technique can also bring touch interactivity to rapidly fabricated objects, including those that are laser cut or 3D printed. Through a series of studies and illustrative example uses, we show that Electrick can enable new interactive opportunities on a diverse set of objects and surfaces that were previously static.