Use Of Electric Fields Research Articles

Electric Field Manipulation of the Dzyaloshinskii–Moriya Interaction in Hybrid Multiferroic Structures

Electric Field Manipulation of the Dzyaloshinskii–Moriya Interaction in Hybrid Multiferroic Structures

Repelling Aedes aegypti mosquitoes with electric fields using insulated conductor wires.

The control and prevention of mosquito-borne diseases is mostly achieved with insecticides. However, their use has led to the rapid development and spread of insecticide resistance worldwide. Health experts have called for intensified efforts to find new approaches to reduce mosquito populations and human-mosquito contact. A promising new tool is the use of electrical fields (EFs), whereby mosquitoes are repelled by charged particles in their flight path. Such particles move between two or more conductors, and the use of uninsulated copper or aluminum plates as conductors has been proven to be effective at repelling mosquitoes. Here, for the first time, we assess if EFs generated using a single row of insulated conductor wires (ICWs) can also successfully repel mosquitoes, and whether mosquitoes are equally repelled at the same EF strength when the electrodes are a) orientated differently (horizontal vs. vertical placement), and b) spaced more apart. Over a period of 23 hours, the number of host-seeking female Aedes aegypti mosquitoes that were successfully repelled by EFs, using ICWs, at EF strengths ranging from 0 kV/cm (control) to 9.15 kV/cm were quantified. Mosquitoes were released inside a 220×220×180 cm room and lured into a BG-Pro trap that was equipped with a BG-counter and baited with CO2 using dry ice. Mosquitoes had to pass through an EF window, that contained a single row of ICWs with alternating polarity, to reach the bait. The baseline interaction between EF strength and repellency was assessed first, after which the impact of different ICW orientations and ICW distances on repellency were determined. Over 50% of mosquitoes were repelled at EF strengths of ≥ 3.66 kV/cm. A linear regression model showed that a vertical ICW orientation (vertical vs. horizontal) had a small but insignificant increased impact on mosquito repellency (p = 0.059), and increasing ICW distance (while maintaining the same EF strength) significantly reduced repellency (p = 0.01). ICWs can be used to generate EFs that partially repel host-seeking mosquitoes, which will reduce human-mosquito contact. While future studies need to assess if (i) increased repellency can be achieved, and (ii) a repellency of 50-60% is sufficient to impact disease transmission, it is encouraging that EF repellency using ICWs is higher compared to that of some spatial repellent technologies currently in development. This technology can be used in the housing improvement toolkit (i.e. preventing mosquito entry through eaves, windows, and doors). Moreover, the use of cheap, over-the-counter ICWs will mean that the technology is more accessible worldwide, and easier to manufacture and implement locally.

Electric-Field Manipulation of Magnetic Chirality in a Homo-Ferro-Rotational Helimagnet.

Ferro-rotational (FR) materials, renowned for their distinctive material functionalities, present challenges in the growth of homo-FR crystals (i.e., single FR domain). This study explores a cost-effective approach to growing homo-FR helimagnetic RbFe(SO4)2 (RFSO) crystals by lowering the crystal growth temperature below the TFR threshold using the high-pressure hydrothermal method. Through polarized neutron diffraction experiments, it is observed that nearly 86% of RFSO crystals consist of a homo-FR domain. Notably, RFSO displays remarkable stability in the FR phase, with an exceptionally high TFR of ≈573K. Furthermore, RFSO exhibits a chiral helical magnetic structure with switchable ferroelectric polarization below 4K. Importantly, external electric fields can induce a single magnetic domain state and manipulate its magnetic chirality. The findings suggest that the search for new FR magnets with outstanding material properties should consider magnetic sulfates as promising candidates.

(Invited) Simultaneous Use of Electric Fields and Plasmonic Carriers for Catalysis

The visible-light excitation of plasmonic nanostructures is now well known to induce catalytic reactions that are not otherwise observed in the dark. One example we have discovered is the conversion of carbon dioxide to hydrocarbons on gold nanoparticles driven by electron–hole pairs generated by plasmonic excitation. However, conversions driven by plasmonically generated carriers can suffer from thermodynamic and efficiency limits. I will describe how such limits can be overcome by simultaneous use of electric fields and plasmonically generated carriers.

The Use of External Fields (Magnetic, Electric, and Strain) in Molecular Beam Epitaxy-The Method and Application Examples.

Molecular beam epitaxy (MBE) is a powerful tool in modern technologies, including electronic, optoelectronic, spintronic, and sensoric applications. The primary factor determining epitaxial heterostructure properties is the growth mode and the resulting atomic structure and microstructure. In this paper, we present a novel method for growing epitaxial layers and nanostructures with specific and optimized structural and magnetic properties by assisting the MBE process using electromagnetic and mechanical external stimuli: an electric field (EF), a magnetic field (MF), and a strain field (SF). The transmission of the external fields to the sample is realized using a system of specialized sample holders, advanced transfers, and dedicated manipulators. Examples of applications include the influence of MFs on the growth and anisotropy of epitaxial magnetite and iron films, the use of EFs for in situ resistivity measurements, the realization of in situ magneto-optic measurements, and the application of SFs to the structural modification of metal films on mica.

Electrically Induced Crystal Field Distortion in a Ferroelectric Perovskite Revealed by Electron Paramagnetic Resonance.

The magnetoelectric material has attracted multidisciplinary interest in the past decade for its potential to accommodate various functions. Especially, the external electric field can drive the quantum behaviors of such materials via the spin-electric coupling effect, with the advantages of high spatial resolution and low energy cost. In this work, the spin-electric coupling effect of Mn2+-doped ferroelectric organic-inorganic hybrid perovskite [(CH3)3NCH2Cl]CdCl3 with a large piezoelectric effect was investigated. The electric field manipulation efficiency for the allowed transitions was determined by the pulsed electron paramagnetic resonance. The orientation-included Hamiltonian of the spin-electric coupling effect was obtained via simulating the angle-dependent electric field modulated continuous-wave electron paramagnetic resonance. The results demonstrate that the applied electric field affects not only the principal values of the zero-field splitting tensor but also its principal axis directions. This work proposes and exemplifies a route to understand the spin-electric coupling effect originating from the crystal field imposed on a spin ion being modified by the applied electric field, which may guide the rational screening and designing of hybrid perovskite ferroelectrics that satisfy the efficiency requirement of electric field manipulation of spins in quantum information applications.

Towards rapid formation of electroactive biofilm: insights from thermodynamics and electric field manipulation

Electroactive biofilm (EAB) has garnered significant attention due to its effectiveness in pollutant remediation, electricity generation, and chemical synthesis. However, achieving precise control over the rapid formation of EAB presents challenges for the practical implementation of bioelectrochemical technology. In this study, we investigated the regulation of EAB formation by manipulating applied electric potential. We developed a modified XDLVO model for the applied electric field and quantitatively assessed the feasibility of existing rapid formation strategies for EAB. Our results revealed that electrostatic (EL) force significantly influenced EAB formation in the presence of the applied electric field, with the potential difference between the electrode and the microbial solution being the primary determinant of EL force. Compared to -0.2 V and 0 V vs.Ag/AgCl, EAB exhibited the highest electrochemical performance at 0.2 V vs.Ag/AgCl, with a maximum current density of 6.044 ± 0.10 A/m2, surpassing that at -0.2 V vs.Ag/AgCl and 0 V vs.Ag/AgCl by 1.73 times and 1.31 times, respectively. Furthermore, EAB demonstrated the highest biomass accumulation, measuring a thickness of 25 ± 2 μm at 0.2 V vs. Ag/AgCl, representing increases of 1.67 and 1.25 times compared to -0.2 V vs.Ag/AgCl and 0 V vs.Ag/AgCl, respectively. The strong electrostatic attraction under the anodic potential promoted the formation of a monolayer of biofilm. Additionally, the hydrophilicity and hydrophobicity of the biofilm were altered following inversion culture. The Lewis acid-base (AB) attraction offset the electrostatic repulsion caused by negative charges, it is beneficial for the formation of biofilms. This study, for the first time, elucidated the difference in the formation of cathode and anode biofilm from a thermodynamic perspective in the context of electric field introduction, laying the theoretical foundation for the directional regulation of the rapid formation of typical electroactive biofilms.

Enhanced magnetic property and magnetodielectric coupling effect in multiferroic Gd2BaCuO5 via Zn2+ doping

The multiferroics with remarkable magnetoelectric (ME) coupling and technological application have drawn significant attention. Here, we report a chemical doping tunable effect on the magnetic, ferroelectric, and dielectric properties in type-II multiferroic Gd2BaCuO5. The magnetic measurement results show that a long-range antiferromagnetic ordering forms at the Néel temperature (TN1) of ∼12.1 K, and a second magnetization anomaly occurs at a lock-in transition temperature (TN2) of ∼6.4 K. Sharp peaks in the pyroelectric and dielectric curves are observed at the magnetic transition temperatures, indicating intrinsic coupling between magnetic and ferroelectric orderings. The doping of Zn2+ results in a gradual enhancement of magnetization due to the increase of uncompensated spins, and large magnetodielectric (MD) coupling parameter up to ∼7.65 % is obtained in Gd2BaCu0.7Zn0.3O5 because of strong spin-phonon coupling. The ferroelectric property is weakened in Zn2+ doped samples, suggesting the critical role of the 4f-3d magnetic interactions in determining the ME coupling effect. Moreover, an effective manipulation of electric field on magnetization is observed in Gd2BaCuO5. This work helps understand the importance of 4f-3d magnetic interactions in inducing ferroelectricity and explore the ME and MD coupling effects with multiple magnetic orderings.

Highly controlled multiplex electrospinning

Applications of electrospinning (ES) range from fabrication of biomedical devices and tissue regeneration scaffolds to light manipulation and energy conversion, and even to deposition of materials that act as growth platforms for nanoscale catalysis. One major limitation to wide adoption of ES is stochastic fiber deposition resulting from the chaotic motion of the polymer stream as is approaches the deposition surface. In the past, fabrication of structures or materials with precisely determined mesoscale morphology has been accomplished through modification of electrode shape, use of multi-dimensional electrodes or pins, deposition onto weaving looms, hand-held electrospinning devices that allow the user to guide deposition, or electric field manipulation by lensing elements or apertures. In this work, we demonstrate an ES system that contains multiple high voltage power supplies that are independently controlled through a control algorithm implemented in LabVIEW. The end result is what we term “multiplex ES” where multiple independently controlled high-voltage signals are combined by the ES fiber to result in unique deposition control. COMSOL Multiphysics® software was used to model the electric field produced in this novel ES system. Using the multi-power supply system, we demonstrate fabrication of woven fiber materials that do not require complex deposition surfaces. Time-varied sinusoidal wave inputs were used to create electrospun torus shapes. The outer diameter of the tori was found, through parametric analysis, to be rather insensitive to frequency used during deposition, while inner diameter was inversely related to frequency, resulting in overall width of the tori increasing with frequency. Multiplex ES has a high-frequency cutoff based on the time response of the high voltage electrical circuit. These time constants were measured and minimized through the addition of parallel resistors that decreased impedance of the system and improved the high-frequency cutoff by up to 63%.

Spin-Orbit Torque in Single-Molecule Junctions from ab Initio.

The use of electric fields applied across magnetic heterojunctions that lack spatial inversion symmetry has been previously proposed as a nonmagnetic means of controlling localized magnetic moments through spin-orbit torques (SOT). The implementation of this concept at the single-molecule level has remained a challenge, however. Here, we present first-principles calculations of SOT in a single-molecule junction under bias and beyond linear response. Employing a self-consistency scheme invoking density functional theory and nonequilibrium Green's function theory including spin-orbit interaction, we compute the change of the magnetization with the bias voltage and the associated current-induced SOT. Within the linear regime our quantitative estimates for the SOT in single-molecule junctions yield values similar to those known for magnetic interfaces. Our findings contribute to an improved microscopic understanding of SOT in single molecules.

Enhanced performance of normally-OFF GaN HEMTs with stair-shaped p-GaN cap layer

The p-GaN-gated E-mode HEMTs (P-HEMTs) are being extensively studied for emerging power electronics. However, the devices still suffer from performance trade-off among threshold voltage (V TH), output drain current (I DS), and breakdown voltage (V BD). Herein, we propose a P-HEMT with a stair-like p-GaN cap layer to boost their performance. The p-GaN cap layer is composed of four discrete p-GaN staircases with the decreased thickness to the right (Right-Stair P-HEMT) or to the left (Left-Stair P-HEMT). It is found that the RSP-HEMT simultaneously achieves the 1.3 times increased I DS, 160 V enhanced V BD, and improved V TH stability against drain-induced barrier lowering effects, compared with the LSP-HEMT and the conventional BaSeline P-HEMT. These device merits should be attributed to the effective manipulation of the lateral electric field (E F) under all bias conditions by the unique band structures enabled by the RSP configuration. Such E F manipulation strategies offer us helpful guidance and insights to further propel the development of high-performance E-mode P-HEMTs.

Electric field-assisted dried blood spot sample preparation for analysis of steroids using LC–MS/MS

Despite being a minimally invasive sample source, dried blood spots (DBS) generally pose the challenge of efficient sample extraction for broad metabolomics applications. This is particularly true for the quantification of steroids using non-derivatized liquid chromatography tandem mass spectrometry assays. To address these limitations, we have demonstrated the use of electric field as a driver for sample preparation from DBS samples to simultaneously quantify testosterone (T), 17α-hydroxyprogesterone (17-OHP), progesterone (P), and cortisol (C), using both standard electroporation cuvettes, as well as a novel custom vertical electric field setup. Our findings, backed by computational modeling, show that a 10V DC application for 180 s can draw out twice the amount of the aforementioned steroids from both Whatman-903 and DMPK-C sample collection cards using our novel device when compared to standard solvent-based collection methods. This study not only introduces the use of electric field for sample preparation for metabolomics, but additionally introduces a novel device that eliminates the electric double layer effect in the process.

Electrothermal free-form additive manufacturing of thermosets

Despite the extensive use of thermosetting resins, additive manufacturing of such materials is limited. Traditional processing requires either (i) long curing schedules to avoid the collapse of an uncured printed part or (ii) changes to the resin chemistry and curing mechanism. This work demonstrates a material-extrusion based setup capable of printing and curing any industry-standard thermoset resin through the use of electric fields and carbon nanomaterial susceptors. A material extrusion printer is used to deposit the liquid ink, composed of uncured epoxy with a carbon nanotube filler. After each layer is deposited, the nanotube-loaded ink is exposed to radio frequency (RF) fields generated by a coaxial applicator suspended over the part. The resulting current generates heat rapidly and volumetrically, thus curing the resin, preventing part collapse, and enabling further printing. This methodology enables rapid additive manufacturing of arbitrarily large structures with low viscosity resins that are otherwise impossible to print.

Disclosing the intrinsic nature of efficient removal of antibiotics in N/S dual-doped porous carbon-based materials: The manipulation of internal electric field

N/S co-doping has emerged as a prevailing strategy for carbon-based adsorbents to facilitate the antibiotic removal efficiency. Nevertheless, the underlying interplay among N, S, and their adjacent vacancy defects remains overlooked. Herein, we present a novel in situ strategy for fabricating pyridinic-N dominated and S dual-doped porous carbon adsorbent with rich vacancy defects (VNSC). The experimental results revealed that N (acting as the electron donor) and S (acting as the electron acceptor) form an internal electric field (IEF), with a stronger IEF generated between pyridinic-N and S, while their adjacent vacancy defects activate carbon π electrons, thus enhancing the charge transfer of the IEF. Density functional theory (DFT) calculations further demonstrated that the rich charge transfer in the IEF facilitated the π-π electron donor-acceptor (EDA) interaction between VNSC and tetracycline (TC) as well as norfloxacin (NOR), and thus is the key to adsorption performance of VNSC. Consequently, VNSC exhibited high adsorption capacities toward TC (573.1 mg g−1) and NOR (517.0 mg g−1), and its potential for environmental applications was demonstrated by interference, environmentally relevant concentrations, fixed-bed column, and regeneration tests. This work discloses the natures of adsorption capacity for N/S dual-doped carbon-based materials for antibiotics.

Revisiting N, S co-doped carbon materials with boosted electrochemical performance in sodium-ion capacitors: The manipulation of internal electric field

Revisiting N, S co-doped carbon materials with boosted electrochemical performance in sodium-ion capacitors: The manipulation of internal electric field

Atomic-Scale Visualization of Multiferroicity in Monolayer NiI2.

Progress in layered van der Waals materials has resulted in the discovery of ferromagnetic and ferroelectric materials down to the monolayer limit. Recently, evidence of the first purely 2D multiferroic material wasreported in monolayer NiI2. However, probing multiferroicity with scattering-based and optical bulk techniques is challenging on 2D materials, and experiments on the atomic scale are needed to fully characterize the multiferroic order at the monolayer limit. Here, scanning tunneling microscopy (STM) supported by density functional theory (DFT) calculations is used to probe and characterize the multiferroic order in monolayer NiI2. It is demonstrated that the type-II multiferroic order displayed by NiI2, arising from the combination of a magnetic spin spiral order and a strong spin-orbit coupling, allows probing the multiferroic order in the STM experiments. Moreover, the magnetoelectric coupling of NiI2 is directly probed by external electric field manipulation of the multiferroic domains. The findings establish a novel point of view to analyze magnetoelectric effects at the microscopic level, paving the way toward engineering new multiferroic orders in van der Waals materials and theirheterostructures.

Creation and annihilation of artificial magnetic skyrmions with the electric field

Recent theory and experiments show that artificial magnetic skyrmions can be stabilized at room temperature without the need for the external magnetic field, casting strong potentials for the device applications. In this work, we study the electric field manipulation of artificial magnetic skyrmions imprinted by Co disks on CoPt multilayers utilizing the micromagnetic simulations. We find that the reversible annihilation and creation of skyrmions can be realized with the electric field via the strain mediated magnetoelastic coupling. In addition, we also demonstrate controllable manipulation of individual skyrmion, which opens a new platform for constructing magnetic field-free and low-energy dissipation skyrmion based media.

Experimental evaluation of saturation capacitance in aging phenomena in multi-layer ceramic capacitors (MLCCs)

Aging in dielectrics manifests as a reduction in capacitance over time owing to the applied electric field. This study revisits the aging mechanism in multi-layer ceramic capacitors (MLCCs), specifically considering DC-bias voltage and temperature variables. The findings indicate that aging is intensified by higher DC-bias voltages (electric field strength) and elevated temperatures, ultimately leading to capacitance saturation. A poling–depoling experiment confirms the rapid assessment of saturation capacitance. Consequently, we propose a straightforward method involving electric field manipulation to quantitatively evaluate the saturated capacitance of MLCCs under aging conditions. The estimated capacitance aligns closely with the measured capacitance after 2000 h, with an error rate not exceeding 4 %.

Therapeutic perspectives of high pulse repetition rate electroporation

Electroporation, a technique that uses electrical pulses to temporarily or permanently destabilize cell membranes, is increasingly used in cancer treatment, gene therapy, and cardiac tissue ablation. Although the technique is efficient, patients report discomfort and pain. Current strategies that aim to minimize pain and muscle contraction rely on the use of pharmacological agents. Nevertheless, technical improvements might be a valuable tool to minimize adverse events, which occur during the application of standard electroporation protocols. One recent technological strategy involves the use of high pulse repetition rate. The emerging technique, also referred as “high frequency” electroporation, employs short (micro to nanosecond) mono or bipolar pulses at repetition rate ranging from a few kHz to a few MHz. This review provides an overview of the historical background of electric field use and its development in therapies over time. With the aim to understand the rationale for novel electroporation protocols development, we briefly describe the physiological background of neuromuscular stimulation and pain caused by exposure to pulsed electric fields. Then, we summarize the current knowledge on electroporation protocols based on high pulse repetition rates. The advantages and limitations of these protocols are described from the perspective of their therapeutic application.

Characterization of electronic structure, magnetism, and electric field manipulation in non-metal doped monolayer 1T-HfS2

We have explored the influence of low-concentration doping with various non-metallic elements on the chemical bonding characteristics, electronic structure, and magnetism of monolayer 1T-HfS2 using the first-principles method based on density functional theory. The investigations revealed that the formation energy of the doping systems is influenced by the atomic number of the dopant atoms, diminishing as dopant atoms move further away from S in the periodic table. The hybridization between dopant atoms and neighboring Hf atoms resulted in spin splitting near the Fermi level, leading to the emergence of magnetism in the B and C doping systems. Furthermore, the introduction of an externally applied weak electric field, while not altering the fundamental characteristics of the system, allowed for fine-tuning of the band gap and magnetism. This study has revealed the impact of different types of doping atoms and external weak electric fields on the electronic properties of monolayer 1T-HfS2 material.