Electrical Switching Research Articles

Strong lateral exchange coupling and current-induced switching in single-layer ferrimagnetic films with patterned compensation temperature

Interlayer couplings are widely used in spintronic devices based on magnetic multilayers. Here, the authors demonstrate instead a strong tunable coupling between adjacent regions of a single ferrimagnetic layer, based on the exchange interaction. They unveil a large lateral exchange bias by spatially patterning the compensation temperature of the ferrimagnet. Furthermore, they show electrical switching of ferrimagnetic domains utilizing the lateral exchange coupling mechanism in combination with spin-orbit torques.

Electrically Switchable Persistent Spin Texture in a Two-Dimensional Hybrid Perovskite Ferroelectric.

As a momentum-independent spin configuration, persistent spin texture (PST) could avoid spin relaxation and play an advantageous role in spin lifetime. Nevertheless, manipulation of PST is a challenge due to the limited materials and ambiguous structure-property relationships. Herein, we present electrically switchable PST in a new 2D perovskite ferroelectric, (PA)2 CsPb2 Br7 (where PA is n-pentylammonium), which has a high Curie temperature of 349 K, evident spontaneous polarization (3.2 μC cm-2 ) and a low coercive electric field of 5.3 kV cm-1 . The combination of symmetry-breaking in ferroelectrics and effective spin-orbit field facilitates intrinsic PST in the bulk and monolayer structure models. Strikingly, the directions of spin texture are reversible by switching the spontaneous electric polarization. This electric switching behavior relates to the tilting of PbBr6 octahedra and the reorientation of organic PA+ cations. Our studies on ferroelectric PST of 2D hybrid perovskites afford a platform for electrical spin texture manipulation.

Electrically Switchable Persistent Spin Texture in a Two‐Dimensional Hybrid Perovskite Ferroelectric

AbstractAs a momentum‐independent spin configuration, persistent spin texture (PST) could avoid spin relaxation and play an advantageous role in spin lifetime. Nevertheless, manipulation of PST is a challenge due to the limited materials and ambiguous structure–property relationships. Herein, we present electrically switchable PST in a new 2D perovskite ferroelectric, (PA)2CsPb2Br7 (where PA is n‐pentylammonium), which has a high Curie temperature of 349 K, evident spontaneous polarization (3.2 μC cm−2) and a low coercive electric field of 5.3 kV cm−1. The combination of symmetry‐breaking in ferroelectrics and effective spin‐orbit field facilitates intrinsic PST in the bulk and monolayer structure models. Strikingly, the directions of spin texture are reversible by switching the spontaneous electric polarization. This electric switching behavior relates to the tilting of PbBr6 octahedra and the reorientation of organic PA+ cations. Our studies on ferroelectric PST of 2D hybrid perovskites afford a platform for electrical spin texture manipulation.

Ultrabroadband Multichannel Vector Vortex Beams With Versatile Electrically Induced Functionality

AbstractThe emergence of vector vortex beams (VVBs) has opened new avenues for various applications in optics and photonics. However, owing to the formidable phase aberration ascribed to the chromatic dispersion, the generation of VVBs suffers from a limited working spectrum, thus rendering the massive integration level and functionality challenging. Here, this work proposes a creative paradigm to generate ultrabroadband multichannel VVBs, via programming the electric field vector through the twisted nematic liquid crystals configured by photopatterning. It is experimentally demonstrated the multichannel VVBs propagate along a group of diffraction orders among an unprecedented bandwidth over 1000 nm covering the visible and NIR band, and the working spectrum can be extended into the mid‐IR region even at 10 µm wavelength with a sufficient efficiency of more than 80%. Remarkably, distinct from the usual electrical switching on–off cycle, the multichannel VVBs can be optionally regulated in either a reversible or irreversible manner by conveniently adjusting the applied voltage, thus endowing the versatile functionality for smart control and confidential purposes. The combination of multichannel VVB generation, ultrabroad spectral range, versatile controllability, and simplicity renders the methodology quite promising in photonics, quantum science, and fundamental physics.

Nonvolatile Magnetoelectric Switching of Magnetic Tunnel Junctions with Dipole Interaction

AbstractThe magnetoelectric effect is technologically appealing because of its ability to manipulate magnetism using an electric field rather than magnetic field or current, thus providing a promising solution for the development of energy‐efficient spintronics. Although 180° magnetization switching is vital to spintronic devices, the achievement of 180° magnetization switching via magnetoelectric coupling is still a fundamental challenge. Herein, voltage‐driven full resistance switching of a magnetic tunnel junction (MTJ) with dipole interaction on a ferroelectric substrate through switchable parallel/antiparallel magnetization alignment is demonstrated. Parallel magnetization alignment along the y direction is obtained under a bias magnetic field. By rotating the magnetic easy axis via strain‐mediated magnetoelectric coupling, the parallel magnetizations in the MTJ reorient to the x axis with opposite paths because of dipole interaction, thus resulting in antiparallel alignment. Moreover, this voltage switching of MTJs is nonvolatile owing to variations in dipole interaction and can be well understood via phase field simulations. The results provide an avenue to realize electrical switching of MTJs and are significant for exploring energy‐efficient spintronic devices.

A Polymorphic Memtransistor with Tunable Metallic and Semiconducting Channel.

Modulating semiconducting channel potential has been used for electrical switching in transistors without biological plasticity operations that are critical for energy-efficient neuromorphic computing. To achieve efficient data processing, alternative transport mechanisms, such as tunneling and thermionic emission, have been introduced with 2D materials. Here, a polymorphic memtransistor based on atomically thin Mo0.91 W0.09 Te2 is presented, where the lattice and electronic structures of the lateral device channel can be tuned as either metallic (1T') or semiconducting (2H) phases by electrical gating. The structural and electronic phase change of the channel material, optimized in Mo0.91 W0.09 Te2 , is explored using transport and optical measurements at the device scale. Based on the phase transition, the polymorphic memtransistor demonstrates a high on/off ratio (up to 105 ), low subthreshold swing (down to 80mV dec-1 ), and various memristive behaviors, which are distinguished from traditional phase-change memory, transistors, and passive memristors for diverse neuromorphic and in-memory computing.

나노위성 전개스위치 구현 사례 및 고찰

Most Nanosatellites are launched in nanosatellite deployers. Nanosatellites in the deployer are turned off during launch, and they start boot sequence after deploying at their mission orbit. For this reason, nanosatellites must have deployment switch. Most of the nanosatellite deployment switch has two part, first is electric switch to boot the satellite system and second is mechanical assembly to push the switch. In most cases, electric switches are installed in the satellite main body, and the switch operations are translated via the mechanical assembly. These implementations are mechanically complicated and hard to guarantee the appropriate operation without the problems due to friction between pusher and satellite structure. This paper proposes the another implementation method of deployment switch for nano-satellites by installing the electric switch outside the main body without any kind of mechanical parts.

Thermoresponsive Conductivity of Graphene-Based Fibers.

Smart materials are versatile material systems which exhibit a measurable response to external stimuli. Recently, smart material systems have been developed which incorporate graphene in order to share on its various advantageous properties, such as mechanical strength, electrical conductivity, and thermal conductivity as well as to achieve unique stimuli-dependent responses. Here, a graphene fiber-based smart material that exhibits reversible electrical conductivity switching at a relatively low temperature (60°C), is reported. Using molecular dynamics (MD) simulation and density functional theory-based non-equilibrium Green's function (DFT-NEGF) approach, it is revealed that this thermo-response behavior is due to the change in configuration of amphiphilic triblock dispersant molecules occurring in the graphene fiber during heating or cooling. These conformational changes alter the total number of graphene-graphene contacts within the composite material system, and thus the electrical conductivity as well. Additionally, this graphene fiber fabrication approach uses a scalable, facile, water-based method, that makes it easy to modify material composition ratios. In all, this work represents an important step forward to enable complete functional tuning of graphene-basedsmart materials at the nanoscale while increasing commercialization viability.

Formulas calculating the reactance of tubular busbars and their derivation in primary electrical connection schemes

Electrical switching operation in a substation which locates in a high-voltage transmission system alters operating modes of main wiring in either the substation or the system. Major alterations may have negative influences on the switchgear of main wiring in a short time. The quantitative study of this problem has to be based on establishing equivalent circuits of main wiring, when there rarely are formulas to calculate the reactance of tubular busbars. In this paper on the basis of the electromagnetic field theory, the magnetic induction and flux linkages outside and inside tubular conductors are obtained from the Ampere Loop Theorem, and then the formulas to calculate approximately the reactance of tubular busbars with a three-phase parallel arrangement are derived. From the process and results of the calculation in an example it may be seen that the formulas are applied simply, conveniently and rapidly, and may be valuably spread in practical electrical engineering.

Step electrical switching in VO2 on hexagonal boron nitride using confined individual metallic domains

Vanadium dioxide (VO2) exhibits an insulator–metal transition (IMT) accompanied with a giant resistance change, which is attractive for the application of devices, such as switching devices. Since the behavior of individual domains determines the total IMT property of the VO2 sample, the steep resistance change from a single domain can be identified and utilized in a sample whose size is as small as the individual domain size. Uniquely, micro-structured VO2 thin films on hexagonal boron nitride (hBN) exhibit step resistance changes owing to the confined metallic domains. In this study, we demonstrated step electrical switching in the two-terminal VO2 sample produced on hBN. Operando structural and electric investigation revealed that the emergence of metallic domains in the micrometer space contributes to the step electric current increase. Our results indicate the use of individual metallic domains in VO2 thin films on hBN in the application of novel devices.

Modulation of Switching Characteristics in a Single VO2 Nanobeam with Interfacial Strain via the Interconnection of Multiple Nanoscale Channels.

We demonstrate the modulation of electrical switching properties through the interconnection of multiple nanoscale channels (∼600 nm) in a single VO2 nanobeam with a coexisting metal-insulator (M-I) domain configuration during phase transition. The Raman scattering characteristics of the synthesized VO2 nanobeams provide evidence that substrate-induced interfacial strain can be inhomogeneously distributed along the length of the nanobeam. Interestingly, the nanoscale VO2 devices with the same channel length and width exhibit distinct differences in hysteric current-voltage characteristics, which are explained by theoretical calculations of resistance change combined with Joule heating simulations of the nanoscale VO2 channels. The observed results can be attributed to the difference in the spatial distribution and fraction ratios of M-I domains due to interfacial strain in the nanoscale VO2 channels during the metal-insulator transition process. Moreover, we demonstrate the electrically activated resistive switching characteristics based on the hysteresis behaviors of the interconnected nanoscale channels, implying the possibility of manipulating multiple resistive states. Our results may offer insights into the nanoscale engineering of correlated phases in VO2 as the key materials of neuromorphic computing for which nonlinear conductance is essential.

Ultralow voltage (1 μV) electrical switching of SnS thin films driven by a vertical electric field

In this paper, we show in a series of experiments on 10 nm thick SnS thin film-based back-gate transistors that in the absence of the gate voltage, the drain current versus drain voltage (I D–V D) dependence is characterized by a weak drain current and by an ambipolar transport mechanism. When we apply a gate voltage as low as 1 μV, the current increases by several orders of magnitude and the I D–V D dependence changes drastically, with the SnS behaving as a p-type semiconductor. This happens because the current flows from the source (S) to the drain (D) electrode through a discontinuous superficial region of the SnS film when no gate voltage is applied. On the contrary, when minute gate voltages are applied, the vertical electric field applied to the multilayer SnS induces a change in the flow path of the charge carriers, involving the inner and continuous SnS layer in the electrical conduction. Moreover, we show that high gate voltages can tune significantly the SnS bandgap.

Multiple-Droplet Selective Manipulation Enabled by Laser-Textured Hydrophobic Magnetism-Responsive Slanted Micropillar Arrays with an Ultrafast Reconfiguration Rate.

Biomimetic structures based on the magnetic response have attracted ever-increasing attention in droplet manipulation. Till now, most methods for droplet manipulation by a magnetic response are only applicable to a single droplet. It is still a challenge to achieve on-demand and precise control of multiple droplets (≥2). In this paper, a strategy for on-demand manipulation of multiple droplets based on magnetism-responsive slanted micropillar arrays (MSMAs) is proposed. The Glaco-modified superhydrophobic surface is the basis of multiple-droplet manipulation. The droplet's motion mode (pinned, unidirectional, and bidirectional) can be readily fine-tuned by changing the volume of droplets and the speed of the magnetic field. The rapid movement of droplets (10-80 mm/s) in the horizontal direction is realized by the unidirectional waves of the micropillar array driven by a specific magnetic field. The bending angle of micropillars can be rapidly and reversibly adjusted from 0 to 90° under the action of a magnetic field. Meanwhile, the liquid-involved light, electric switch, and biomedical detection can be designed by manipulating the droplets on demand. The superiority of MSMAs in multiple-droplet programmable manipulation opens up an avenue for applications in microfluidic and biomedical engineering.

Topological magnetotransport and electrical switching of sputtered antiferromagnetic Ir20Mn80

Topological magnetotransport in non-collinear antiferromagnets has attracted extensive attention due to the exotic phenomena such as large anomalous Hall effect (AHE), magnetic spin Hall effect, and chiral anomaly. The materials exhibiting topological antiferromagnetic physics are typically limited in special Mn3 X family such as Mn3Sn and Mn3Ge. Exploring the topological magnetotransport in common antiferromagnetic materials widely used in spintronics will not only enrich the platforms for investigating the non-collinear antiferromagnetic physics, but also have great importance for driving the nontrivial topological properties towards practical applications. Here, we report remarkable AHE, anisotropic and negative parallel magnetoresistance in the magnetron-sputtered Ir20Mn80 antiferromagnet, which is one of the most widely used antiferromagnetic materials in industrial spintronics. The ab initio calculations suggest that the Ir4Mn16 (IrMn4) or Mn3Ir nanocrystals hold nontrivial electronic band structures, which may contribute to the observed intriguing magnetotransport properties in the Ir20Mn80. Further, we demonstrate the spin–orbit torque switching of the antiferromagnetic Ir20Mn80 by the spin Hall current of Pt. The presented results highlight a great potential of the magnetron-sputtered Ir20Mn80 film for exploring the topological antiferromagnet-based physics and spintronics applications.

Performance Analysis of Scalable Optical Circuit Switch Employing Fast-Tunable AMZI Filters for Coherent Detection

High-port-count optical switches are expected to resolve the envisaged bandwidth and power crunch in intra-data center networks stemming from the slowdown of Moore's Law. This paper briefly reviews electrical switching technologies in current intra-data centers and discusses requirements for optical circuit switches in future data centers. We highlight an optical switch architecture that combines the two independent dimensions of space and wavelength to realize large port counts and fast switching. Wavelength routing is implementable with receiver-side channel selection using wavelength tunable filters (TFs). Coherent detection necessitates a fast-tunable local oscillator (LO) at the receiver. It can be cost-effectively realized using an LO bank that consists of fixed-wavelength laser sources and Silicon-photonic asymmetric Mach-Zehnder interferometer (AMZI) filters. Colorless detection that removes a TF at the front of the receiver is possible when the number of wavelength-division multiplexing (WDM) channels is small, however, as the number exceeds a certain limit the TF is needed to prevent power saturation of the receiver. We present an effective cooperative filtering scheme for transmission signals and LO channels sourced from an LO bank; it can detect C-band WDM coherent signals while easing the receiver's power limitation. The scheme is analyzed to clarify receiver performance and the switch port-count bounds under various operating conditions. We demonstrate that the cooperative filtering scheme effectively works from 60 (typical of coherent receivers) to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ &gt; $</tex-math></inline-formula> 116 wavelength channels, which is verified by experiments for 1,856 × 1,856 optical switching with the short switching time of 3.2 μs.

High voltage power supply for steady state operation of the neutral beam test facility ELISE

The Neutral Beam Injection (NBI) system of ITER shall provide 33 MW heating power to the plasma for up to one hour by two injectors. The beam lines will be based on large RF-driven sources for negative hydrogen or deuterium ions. The test facility ELISE (Extraction from a Large Ion Source Experiment) at IPP Garching is supporting the ion source development for ITER with an ion source of 1 × 1 m2 (half the size of the ITER source). While plasma operation of ELISE is possible for up to one hour, the extraction and acceleration of a negative ion beam (up to 60 kV) was initially possible only for ≈10 s every ≈150 s with the old power supply. During such pulses the temporal behavior of the co-extracted electrons significantly depends on whether beam extraction is switched on or off. Thus, continuous wave (CW) extraction is mandatory for developing fully ITER relevant operational scenarios and recently, a steady state power supply for beam extraction has been installed at ELISE. This power supply consists of two stages connected in series: a first stage with 12 kV / 70 A, providing 35 A for the extracted negative ion current, with a 35 A overhead for co-extracted electrons. The second stage of 50 kV / 35 A is used for the further acceleration of only the ions to a total potential of 60 kV. The two stages have an electrical active power of 1.75 MW and 0.84 MW respectively. The power supply operates with pulse step modulation. Bipolar transistors with insulated gate electrodes (IGBT) are used as electrical switches on the DC side. The 50 kV stage consists of 64 modules in series and the 12 kV stage has 24 modules. Both stages are controlled synchronously and must detect breakdowns between the grids in a µs range.

Electrically switchable anisotropic polariton propagation in a ferroelectric van der Waals semiconductor.

Tailoring of the propagation dynamics of exciton-polaritons in two-dimensional quantum materials has shown extraordinary promise to enable nanoscale control of electromagnetic fields. Varying permittivities along crystal directions within layers of material systems, can lead to an in-plane anisotropic dispersion of polaritons. Exploiting this physics as a control strategy for manipulating the directional propagation of the polaritons is desired and remains elusive. Here we explore the in-plane anisotropic exciton-polariton propagation in SnSe, a group-IV monochalcogenide semiconductor that forms ferroelectric domains and shows room-temperature excitonic behaviour. Exciton-polaritons are launched in SnSe multilayer plates, and their propagation dynamics and dispersion are studied. This propagation of exciton-polaritons allows for nanoscale imaging of the in-plane ferroelectric domains. Finally, we demonstrate the electric switching of the exciton-polaritons in the ferroelectric domains of this complex van der Waals system. The study suggests that systems such as group-IV monochalcogenides could serve as excellent ferroic platforms for actively reconfigurable polaritonic optical devices.

Modeling and Characterization of Surface Discharges in Insulating Material for Spacers: Electrode Shape, Discharge Mode, and Revision of the Creepage Concept.

In the design of MV AC and DC spacers, the predominant factors are surface and interface conditions. Design is generally carried out on specifications and standards which are based on long-term experience and lab testing. However, the diffusion of power electronics with a trend to increase electric field, switching frequency, and rise time to achieve higher power density calls for an innovative, global approach to optimized insulation system design. A new methodology, based on field simulation, discharge modeling, and partial discharge inception measurements, called the three-leg approach, can form the basis to optimize insulation design for any type of supply voltage waveform. This paper focuses on the influence of the type of electrode on the inception and phenomenology of surface discharges and, as a consequence, on the interpretation of the results used for application of the three-leg approach. It is demonstrated that a typical electrode system used for insulating material testing can generate both gas and surface discharges at the triple point, when the electrodes have a smooth profile that is used to avoid corona or flashover. Hence, testing partial discharge may not provide a straightforward indication of the surface discharge inception and, thus, be partially misleading for insulation design. Another takeover is that such analysis must benefit from PD testing tools endowed with analytics able to provide automatic identification of the type of defect generating PD, i.e., internal, surface, and corona, since design and remedy actions can be taken, and adequate insulating materials developed, only knowing the type of source generating PD. Hence, testing partial discharge may not provide a straightforward indication of surface discharge inception and, thus, be partially misleading for insulation design. In addition to the importance of the three-leg approach to favor reliable and optimized design of insulation systems, there is a clear need to have a PD testing tool endowed with analytics. It should preferably be able to provide automatic identification of the type of defect generating PD, i.e., internal, surface, and corona.

Reversible electrical switching of nanostructural color pixels

Abstract Electrical switching of nanophotonic structural color elements is a promising approach towards addressable color switching pixels for next generation reflective displays. However, electrical switching between the primary colors to colorless near-white state remains a challenge. Here, we present a reversible electrical switching approach, relying on the electrocoagulation of Ag nanoparticles between silicon nanostructures that support Mie resonances. The electrodeposited Ag nanoparticles enable the excitation of the hybrid plasmon-Mie resonance as supported on Ag-silicon nanostructures, resulting in a large spectral transformation. Importantly, this process is reversible. This device design outperforms other designs in terms of electrotonic color control since it is highly stable and reliable for use in high-resolution reflective displays, such as colored electronic papers and smart display glass, where the combination is scalable to other nanostructure designs and electrolytic solutions.

Design and Construction of a Micro Controller Based Smart Automated System for Controlling Various Home Appliances

Smart Home Automated System is an inexpensive technology. This study presents the overall design of Home Automation System (HAS) with low cost and wireless system. This system is designed to assist and provide support in order to fulfill the needs of elderly and disabled in home. Also, the smart home concept in the system improves the standard of living at home. The sensors, relays and web browser are used to control the home appliances. The main control system implements wireless technology to provide remote access from smart phone. The design removes the existing electrical switches and provides more safety control on the switches with low voltage activating method. The system intends to control electrical appliances and devices in house with relatively low cost design, user- friendly interface and ease of installation. Alternatively, SMART HOME AUTOMATED SYSTEM can provide higher level of security and convenience compared to traditionally used systems. The main objective of the current paper is to design and implement cost-efficient and reliable security, safety and automatic home system for protection and occupants’ convenience. If any hazard is being sensed like smoke, excess heat, unauthorized movements etc; the system warns the home-owner in real-time using Short Message Service (SMS). With this project, home appliances can also be controlled within and away from home, at the same time gives access to real time monitoring of the appliances and properties.