Electrical Switching Research Articles

Thickness‐Dependent Bandgap and Atomic Structure in Elemental Tellurium Films

Elemental tellurium electrical switch, relying on a transient crystal–liquid–crystal phase transition, has recently been proposed as a promising selector candidate for the next‐generation 3D high‐density memory, bridging performance gap in today's computer. Further miniaturization of the switch cell to increase memory density strongly depends on the scalability of the tellurium film, which, however, has not been experimentally studied. Herein, the tellurium films are prepared with the thickness downscaled from 400 to 2 nm and a significant increase is found in the bandgap from 0.29 to 0.91 eV, as predicted by ab initio molecular dynamics. Interestingly, the as‐deposited tellurium films with a thickness above 3 nm are in the crystalline trigonal phase, whereas 2 nm thick film suddenly becomes amorphous, observed by both Raman and transmission electron microscopies. In this finding, since the leakage current of the elemental tellurium switch is determined by both the Schottky barrier between tellurium/electrode interface and the bandgap of the tellurium film, a reduction in leakage current is predicted with further miniaturization.

Field-Free Switching of Perpendicular Magnetization in an Ultrathin Epitaxial Magnetic Insulator.

For energy-efficient magnetic memories, switching of perpendicular magnetization by spin-orbit torque (SOT) appears to be a promising solution. This SOT switching requires the assistance of an in-plane magnetic field to break the symmetry. Here, we demonstrate the field-free SOT switching of a perpendicularly magnetized thulium iron garnet (Tm3Fe5O12, TmIG). The polarity of the switching loops, clockwise or counterclockwise, is determined by the direction of the initial current pulses, in contrast with field-assisted switching where the polarity is controlled by the direction of the magnetic field. From Brillouin light scattering, we determined the Dzyaloshinskii-Moriya interaction (DMI) induced by the Pt-TmIG interface. We will discuss the possible origins of field-free switching and the roles of the interfacial DMI and cubic magnetic anisotropy of TmIG. This discussion is substantiated by magnetotransport, Kerr microscopy, and micromagnetic simulations. Our observation of field-free electrical switching of a magnetic insulator is an important milestone for low-power spintronic devices.

Exploring tensions of Industry 4.0 adoption in lean production systems from a dialectical perspective

PurposeThis paper uses dialectical inquiry to explore tensions that arise when adopting Industry 4.0 technologies in a lean production system and their reconciliation mechanisms.Design/methodology/approachWe conducted an in-depth qualitative case study over a 3-year period on an Italian division of an international electrotechnical organisation that produces electrical switches. This organisation successfully adopted Industry 4.0 technologies in a lean production system. The study is based on primary data such as observations and semi-structured interviews, along with secondary data.FindingsWe identify four empirically validated dialectic tensions arising across different Industry 4.0 adoption stages due to managers’ and workers’ contrasting interpretations of technologies. Consequently, we define the related reconciliation mechanisms that allow the effective adoption of various Industry 4.0 technologies to support a lean production system.Originality/valueThis is the first empirical investigation of tensions in the adoption of Industry 4.0 technologies in a lean production system. Furthermore, the paper presents four theoretical propositions and a conceptual model describing which tensions arise during the adoption of Industry 4.0 technologies in a lean production system and the reconciliation mechanisms that prevent lean production system deterioration.

ODRAD: An optical wireless DCN dynamic-bandwidth reconfiguration with AWGR and deep reinforcement learning

The rapid growth of Data Center Network (DCN) traffic has brought new challenges, such as limited bandwidth, high latency, and packet loss to existing DCNs based on electrical switches. Because of its theoretically unlimited bandwidth and faster data transmission speeds, optical switching can overcome the problems of electrically switched DCNs. Additionally, numerous research works have been devoted to optical wired DCNs. However, static and fixed-topology DCNs based on optical interconnects significantly limit their flexibility, scalability, and reconfigurability to provide adaptive bandwidth for traffic with heterogeneous characteristics. In this study, we propose and conduct performance evaluations on a reconfigurable optical wireless DCN architecture based on distributed Software-Defined Networking (SDN), Deep Reinforcement Learning (DRL), Semiconductor Optical Amplifier (SOA), and Arrayed Waveguide Grating Router (AWGR). Our architecture is called ODRAD (which stands for Optical Wireless DCN Dynamic-bandwidth Reconfiguration with AWGR and Deep Reinforcement Learning). A Mininet simulation model is established to further verify the reconfigurability of the ODRAD network for various server scales. Based on experimental verification, ODRAD achieves an average end-to-end server latency of 5.2μs under a load of 99%. Compression results demonstrate a 17.36% improvement in packet rate latency performance compared to RotorNet and a 15.21% improvement compared to OPSquare at a load of 99% as the ODRAD network scales from 2,560 to 40,960 servers. Furthermore, ODRAD exhibits effective throughput across different routing protocols, DCN scales and loads.

Electric Field Switching of Magnon Spin Current in a Compensated Ferrimagnet.

Manipulation of directional magnon propagation, known as magnon spin current, is essential for developing magnonic devices featuring nonvolatile functionalities and ultralow power consumption. Magnon spin current can usually be modulated by magnetic field or current-induced spin torques. However, these approaches may lead to energy dissipation due to Joule heating. Electric-field switching of magnon spin current without charge current is highly preferred but challenging to realize. By integrating magnonic and piezoelectric materials, the manipulation of the magnon spin current generated by the spin Seebeck effect in the ferrimagnetic insulator Gd3Fe5O12 (GdIG) film on a piezoelectric substrate is demonstrated. Reversible electric-field switching of magnon polarization without applied charge current is observed. Through strain-mediated magnetoelectric coupling, the electric field induces the magnetic compensation transition between two magnetic states of the GdIG, resulting in its magnetization reversal and the simultaneous switching of magnon spin current. This work establishes a prototype material platform that paves the way for developing magnon logic devices characterized by all electric field reading and writing and reveals the underlying physics principles of their functions.

Electrical and Optical Switching in Vanadium Dioxide Nanostructures Decorated with Gold Nanoparticles

The electrical parameters of the semiconductor-metal phase transition in vanadium dioxide nanostructures synthesized by chemical vapor deposition on a silicon substrate (100) and decorated with gold nanoparticles with a surface concentration from 3∙109 to 3∙1010 cm–2 are studied. X-ray phase analysis revealed that the synthesized nanostructures of vanadium dioxide contain a monoclinic M1 phase undergoing a phase transition at a temperature of about 68 °C. The morphology of the surface of vanadium dioxide nanostructures coated with gold nanoparticles was studied using a scanning electron microscope and an atomic force microscope. The characteristics of the temperature phase transition of the initial nanostructures and nanostructures decorated with gold nanoparticles are determined. The temperature dependence of the resistance near the phase transition point of the initial nanostructures showed that the resistance jump is about four orders of magnitude, which confirms their high quality. It is shown that an increase in the surface concentration of gold particles to a value of 3∙1010 cm–2 increases the conductivity of vanadium dioxide at room temperature by about two times, and shifts the phase transition temperature by 5 °C: from 68 °C to 63 °C. Optical switching in vanadium dioxide with an array of gold particles with a size of 9 nm is considered by numerical modeling methods. It is established that the response of the electromagnetic wave from the VO2 material during the phase transition is enhanced due to the excitation of localized plasmon resonance in gold nanoparticles and reaches a local maximum in the region of 600 nm. Additionally, this effect is enhanced at angles of incidence near the pseudo-Brewster angle for vanadium dioxide. The considered hybrid VO2–Au nanostructures are promising as basic nanoelements for next-generation computers, as well as for ultrafast and highly sensitive sensors.

Silver Alloy Surface Modification for Mechanical Property Enhancement in Aviation and Transportation

Silver alloys are often used for electrical switches in railway transportation. However, a well-known issue with these switches is their relatively short application period due to certain disadvantages of silver alloys, mainly their low hardness and low resistance to abrasive wear, in contrast to their excellent electrical conductivity. Therefore, the main goal of this study was to increase or maintain the hardness of the surface layer in order to extend the life of worn parts without compromising their electrical properties. Instead of ceramic particles, as in other studies, metallic powders were used, which could increase the electrical and/or thermal properties of silver alloys. The following work presents the use of laser processing as a relatively new technique for metal and metal alloy surface processing technology. In particular, a process based on the melting of silver (Ag) with metallic powders, such as chromium (Cr) and nickel (Ni) particles, is presented. The aim was for these powders to create intermetallic phases with a silver matrix in the obtained surface layer, significantly improving the mechanical properties based on the formation of the phases coherent or semi-coherent with the silver matrix. Regarding the original practical implications of this work, it was important to investigate the possibility of applying fibre laser for surface property enhancement. The scientific aim was to describe the changes in microstructure and compounds that occurred in the laser-remelted surface silver layer after Ni and Cr particles were fed into the basic silver material. It was concluded that the surface layer obtained after chromium application was without cracks and defects and had a higher hardness than the untreated material. A three-zone structure was also found in the obtained surface layer: (1) the remelted zone, (2) the heat-affected zone, and (3) the matrix material. The remelting zone revealed a higher hardness compared to the untreated material, reaching 92 HV0.3, which is more than twice the initial hardness value.

Non-volatile electrical polarization switching via domain wall release in 3R-MoS2 bilayer

Understanding the nature of sliding ferroelectricity is of fundamental importance for the discovery and application of two-dimensional ferroelectric materials. In this work, we investigate the phenomenon of switchable polarization in a bilayer MoS2 with natural rhombohedral stacking, where the spontaneous polarization is coupled with excitonic effects through asymmetric interlayer coupling. Using optical spectroscopy and imaging techniques, we observe how a released domain wall switches the polarization of a large single domain. Our results highlight the importance of domain walls in the polarization switching of non-twisted rhombohedral transition metal dichalcogenides and open new opportunities for the non-volatile control of their optical response.

Electrical resistance switching of YbFe2O4 single crystal bulk

We report the electrical resistance switching of YbFe2O4, which is one of the electronic ferroelectrics and shows multi-step polarization reversal. The electrical resistance of the single crystal bulk of YbFe2O4 was measured along the c-axis. Three kinds of resistance states were observed: high resistance state (HRS), low resistance state (LRS), and extra low resistance state (ELRS). The as-grown sample was in HRS. The resistance state switched from HRS to LRS under an electric field of ∼180 V/cm. HRS was reproduced under the same magnitude of the electric field in the opposite direction. The switching from LRS to ELRS was assisted by a current flow in the ab-plane, which is orthogonal to the measurement axis (c-axis). The switching from LRS to ELRS was observed under an electric field of ∼140 V/cm during the resistance measurement along the c-axis after a current flow in the ab-plane for a few seconds. The resistance ratio in HRS, LRS, and ELRS was ∼2:1.5:1, which is regarded as a large value considering that the sample size was sub-millimeter order. This multi-step resistive switching is likely due to the multi-step reversal of electric polarization, accompanied by a multi-step change in Schottky barrier height between the sample and electrodes. The currents in the ab-plane are considered to release some pinnings and assist in the polarization reversal.

Smart Energy Public Street Lighting System

Public street lighting illuminates roadways for two, three, and four-wheeled vehicles. Most roads have street lighting for safety and aesthetics. The security feature improves nighttime driver sight. Motorists need appropriate illumination to reduce accidents and crime. Lighting design and placement affect the street’s and city’s nighttime attractiveness. Public street lighting lights utilize uncontrolled electricity, resulting in excessive expenditures. We need a design that effectively manages and uses electrical energy. The IoT-based Public Street Lighting system employing solar panels as battery chargers may be utilized for electrical energy planning. The ESP8266 module provides control, a Wi-Fi module provides Wi-Fi, the relay module provides an electric switch to turn on or off public street lighting lights using the intelligent energy public street lighting application, and solar panels charge the batteries. The system has LDR sensor monitoring, ultrasonic sensors, and a Nodemcu ESP8266 microprocessor. The light sensor module detects light intensity. The Smart Energy, Public Street Lighting app lets officers monitor the process in real time. This program will monitor public street lighting and analyze and graph the data.

Field‐Free Switching of Magnetization in Oxide Superlattice by Engineering the Interfacial Reconstruction

AbstractSpin‐orbit torque resulting from non‐magnetic materials with strong spin‐orbit coupling enables electrically controlled magnetization switching, offering potential applications in ultralow‐power memory and logic devices. However, such switching of perpendicular magnetization usually requires an in‐plane magnetic field along the applied current direction, which limits its use. To address this challenge, an all‐oxide superlattice is designed and fabricated that show both the perpendicular magneto‐crystalline anisotropy and in‐plane magnetic anisotropies induced by interfacial engineering. The results demonstrate that the coexistence of perpendicular and in plane magnetic anisotropy breaks the symmetry and thus enables the pure electrical switching of perpendicular magnetization.

Revealing the Role of the Tetragonal Distortion in the Metal-Insulator Transition of Co- and Fe-Doped NiS.

Although the NiS exhibits the most widely adjustable metal-to-insulator (MIT) properties among the chalcogenides, the mechanisms, with respect to the regulations in their critical temperatures (TMIT), are yet unclear. Herein, we demonstrate the overlooked role associated with the structurally tetragonal distortion in elevating the TMIT of NiS; this is in distinct contrast to the previously expected hybridization and bandwidth regulations that usually reduces TMIT. Compared to the perspective of structure distortions, the orbital hybridization and band regulation of NiS are ∼19 times more effective adjustment in TMIT. As a result, the respective abruptions in both the electrical and thermal resistive switches across the TMIT of NiS can be better preserved in the low-temperature range (<273 K), shedding light on their optimum usage at cryogenic temperatures.

The electrical switching and the non-linear conduction of nanoporous carbon based on organic xerogel

The electrical switching and the non-linear conduction of nanoporous carbon based on organic xerogel

Drain-Induced Multifunctional Ambipolar Electronics Based on Junctionless MoS2.

Applying a drain bias to a strongly gate-coupled semiconductor influences the carrier density of the channel. However, practical applications of this drain-bias-induced effect in the advancement of switching electronics have remained elusive due to the limited capabilities of its current modulation known to date. Here, we show strategies to largely control the current by utilizing drain-bias-induced carrier type switching in an ambipolar molybdenum disulfide (MoS2) field-effect transistor with Pt bottom contacts. Our CMOS-compatible device architecture, incorporating a partially gate-coupled p-n junction, achieves multifunctionality. The ambipolar MoS2 device operates as an ambipolar transistor (on/off ratios exceeding 107 for both NMOS and PMOS), a rectifier (rectification ratio of ∼3 × 106), a reversible negative breakdown diode with an adjustable breakdown voltage (on/off ratio exceeding 109 with a maximum current as high as 10-4 A), and a photodetector. Finally, we demonstrate a complementary inverter (gain of ∼24 at Vdd = 1.5 V), which is highly facile to fabricate without the need for complex heterostructures and doping processes. Our study provides strategies to achieve high-performance ambipolar MoS2 devices and to effectively utilize drain bias for electrical switching.

Electrical switching of the light color reflected from a NiFe/IrMn mirror

Electrical switching of the light color reflected from a NiFe/IrMn mirror

Retracted: CAD-Assisted 3D Assembly of Automobile Electrical Switch considering PSO-BP Neural Network Algorithm

Retracted: CAD-Assisted 3D Assembly of Automobile Electrical Switch considering PSO-BP Neural Network Algorithm

Coupled Ferroelectric-Photonic Memory in a Retinomorphic Hardware for In-Sensor Computing.

The development of all-in-one devices for artificial visual systems offers an attractive solution in terms of energy efficiency and real-time processing speed. In recent years, the proliferation of smart sensors in the growth of Internet-of-Things (IoT) has led to the increasing importance of in-sensor computing technology, which places computational power at the edge of the data-flow architecture. In this study, a prototype visual sensor inspired by the human retina is proposed, which integrates ferroelectricity and photosensitivity in two-dimensional (2D) α-In2Se3 material. This device mimics the functions of photoreceptors and amacrine cells in the retina, performing optical reception and memory computation functions through the use of electrical switching polarization in the channel. The gate-tunable linearity of excitatory and inhibitory functions in photon-induced short-term plasticity enables to encode and classify 12000 images in the Mixed National Institute of Standards and Technology (MNIST) dataset with remarkable accuracy, achieving ≈94%. Additionally, in-sensor convolution image processing through a network of phototransistors, with five convolutional kernels electrically pre-programmed into the transistors is demonstrated. The convoluted photocurrent matrices undergo straightforward arithmetic calculations to produce edge and feature-enhanced scenarios. The findings demonstrate the potential of ferroelectric α-In2Se3 for highly compact and efficient retinomorphic hardware implementation, regardless of ambipolar transport in the channel.

Multivapor-Responsive Controlled Actuation of Starch-Based Soft Actuators.

Multivapor-responsive biocompatible soft actuators have immense potential for applications in soft robotics and medical technology. We report fast, fully reversible, and multivapor-responsive controlled actuation of a pure cassava-starch-based film. Notably, this starch-based actuator sustains its actuated state for over 60 min with a continuous supply of water vapor. The durability of the film and repeatability of the actuation performance have been established upon subjecting the film to more than 1400 actuation cycles in the presence of water vapor. The starch-based actuators exhibit intriguing antagonistic actuation characteristics when exposed to different solvent vapors. In particular, they bend upward in response to water vapor and downward when exposed to ethanol vapor. This fascinating behavior opens up new possibilities for controlling the magnitude and direction of actuation by manipulating the ratio of water to ethanol in the binary solution. Additionally, the control of the bending axis of the starch-based actuator, when exposed to water vapor, is achieved by imprinting-orientated patterns on the surface of the starch film. The effect of microstructure, postsynthesis annealing, and pH of the starch solution on the actuation performance of the starch film is studied in detail. Our starch-based actuator can lift 10 times its own weight upon exposure to ethanol vapor. It can generate force ∼4.2 mN upon exposure to water vapor. To illustrate the vast potential of our cassava-starch-based actuators, we have showcased various proof-of-concept applications, ranging from biomimicry to crawling robots, locomotion near perspiring human skin, bidirectional electric switches, ventilation in the presence of toxic vapors, and smart lifting systems. These applications significantly broaden the practical uses of these starch-based actuators in the field of soft robotics.

Mechanisms of Electrical Switching of Ultrathin CoO/Pt Bilayers.

We study current-induced switching of the Néel vector in CoO/Pt bilayers to understand the underlying antiferromagnetic switching mechanism. Surprisingly, we find that for ultrathin CoO/Pt bilayers electrical pulses along the same path can lead to an increase or decrease of the spin Hall magnetoresistance signal, depending on the current density of the pulse. By comparing these results to XMLD-PEEM imaging of the antiferromagnetic domain structure before and after the application of current pulses, we reveal the details of the reorientation of the Néel vector in ultrathin CoO(4 nm). This allows us to understand how opposite resistance changes can result from a thermomagnetoelastic switching mechanism. Importantly, our spatially resolved imaging shows that regions where the current pulses are applied and regions further away exhibit different switched spin structures, which can be explained by a spin-orbit torque-based switching mechanism that can dominate in very thin films.

Three-Dimensional Visualization of Oxygen-Vacancy Migration and Redistribution in Ca-Substituted BiFeO3.

Ionic movement has received renewed attention in recent years, particularly in the field of ferroelectric oxides, since it is intrinsically linked to chemical reaction kinetics and ferroelectric phase stability. The associated surface electrochemical processes coupled local ionic transport with an applied electric bias, exhibiting very high ionic mobility at room temperature based on a simple electrostatics scenario. However, few studies have focused on the applied-polarity dependence of ionic migration with directly visualized maps. Here, we use incorporated experiments of conductive scanning probe microscopy and time-of-flight secondary ion mass spectrometry to investigate oxygen ionic migration and cation redistribution in ionic oxides. The local concentrations of oxygen vacancies and other cation species are visualized by three-dimensional mappings, indicating that oxygen vacancies tend to be ejected toward the surface. An accumulation of oxygen vacancies and ionic redistribution strongly depend on tip polarity, thus corroborating their role in the electrochemical process. This work illustrates the interplay between ionic kinetics and electric switching.