Search Results (542)

In this study, La_1−xCa_xMnO₃ (LCMO) samples (x = 0.3, 0.4 and 0.5) were synthesized using a sol–gel method and their structural, electronic, magnetic and magneto–transport properties were investigated. Structural analysis by XRD confirmed orthorhombic perovskite structure. FTIR studies indicated the changes in bond length and bond angle of Mn–O/Mn–O–Mn bonds; FESEM/EDAX confirmed a polycrystalline nature. Magneto–transport studies revealed a decrease in ferromagnetic metal–paramagnetic semiconductor transition temperature with the increase in Ca²⁺ content. Magneto–transport studies also revealed that the resistivity in the ferromagnetic metallic region was predominantly governed by the extrinsic spin–polarized tunneling (SPT) mechanism along with double-exchange interaction, whereas charge transport in the paramagnetic semiconducting region at higher temperatures was due to variable-range hopping conduction. Magnetoresistance was at its maximum near the transition temperature, but decreased at lower temperature (77 K). XPS and ⁵⁵Mn IFNMR confirmed coexistence of Mn³⁺/Mn⁴⁺, while IFNMR results at 77 K confirmed high-frequency electron exchange among Mn³⁺ and Mn⁴⁺ ions due to double exchange interaction. VSM studies at 300 K showed that the paramagnetic nature of the samples and susceptibility decreased with the increase in Ca²⁺ content. The close agreement between the magnetoresistance behavior and the ⁵⁵Mn IFNMR results confirms the role of the intrinsic DE interaction in governing the magnetotransport properties of LCMO. Full article

This study presents a high-efficiency T-type three-level inverter for interior permanent magnet synchronous motor (IPMSM) drive applications, featuring a comprehensive performance comparison with a conventional two-level inverter. To address the high switching losses and noticeable harmonic distortion typically associated with conventional two-level configurations, the T-type architecture is developed and evaluated. First, PLECS simulations are conducted to verify the proposed dual-loop control architecture, which integrates field-oriented control (FOC), space-vector pulse-width modulation (SVPWM), and a neutral-point voltage balancing mechanism. Subsequently, a 2.2 kW experimental platform is constructed using silicon carbide (SiC) wide-bandgap (WBG) semiconductor devices. To characterize the dynamic switching behavior of the adopted SiC MOSFETs, a dedicated double-pulse test (DPT) platform is developed to evaluate their switching losses and determine appropriate gate-drive parameters. In addition, the digital control firmware is implemented on a digital signal processor (DSP) platform. The dual-loop control algorithms, SVPWM strategy, and two-layer protection framework are implemented as real-time executable routines, enabling close integration of the control software and hardware platform. Finally, motor drive experiments at switching frequencies of 20 kHz and 40 kHz are performed to validate the proposed system. The experimental results demonstrate that the developed architecture significantly reduces phase-current total harmonic distortion (THD) and improves overall energy conversion efficiency compared with a conventional two-level inverter, confirming its potential for high-efficiency next-generation electric vehicle applications. Full article

Microfluidic Hall-effect biosensors detect superparamagnetic bead labels as they flow past a thin-film Hall element in a microchannel. Designing one couples bead magnetization, stray-field distribution, Hall transport, and channel flow across 14 parameters that finite-element solvers explore only at minutes to hours per configuration. We present a coupled analytical–numerical framework for this signal chain: Clausius–Mossotti bead magnetization with a volume fraction correction, a point-dipole stray field, a volume-averaged Hall voltage, Poiseuille transport, and a Johnson–Nyquist and Hooge $1/f$ noise model, evaluated across 12 sensor presets compiled from the literature, spanning graphene, III–V semiconductors, Si CMOS, bismuth, and topological insulators; any other platform can be defined from user-supplied transport parameters. Benchmarked against a companion COMSOL Multiphysics 6.0 study, the framework reproduces the Hall voltage to within 4.8% at a favorable bead-to-sensor area ratio and deviates by 22% and 15% at off-optimum geometries, consistent with the point-dipole near-field limit at $h/r_b=1$. Three design rules follow: a signal-to-noise ridge at sensor widths comparable to the bead diameter ($w^{*}\approx d_b$; area ratios 0.4–1.0 at constant voltage, 0.5–2.6 at constant current), matching reported single-bead geometries; a material choice that must be made under an explicit electrical drive constraint; and a sampling-limited flow-velocity window. Predicted signals agree at the order-of-magnitude level with published InAs and Si CMOS experiments. We release the model as a freely accessible, no-install browser implementation with a built-in 2D axisymmetric magnetostatic finite-element (FEM) solver that maps where the dipole approximation degrades. Full article

A complementary metal oxide semiconductor (CMOS)-compatible z-axis magnetic field sensor incorporating an additional collector is proposed to enhance magnetic sensing performance. The sensor consists of four identical magnetic sensing elements arranged in a cross-shaped configuration, while shallow trench isolation (STI) and a post-CMOS cavity structure are employed to suppress substrate leakage current and improve electrical isolation. The sensing characteristics were investigated using three-dimensional TCAD simulations to analyze carrier transport and current density distributions under different magnetic fields. The simulation results confirmed that the structure effectively enhances the differential output response and magnetic sensitivity. The device was fabricated using a commercial CMOS process followed by a simple post-CMOS micromachining process. Optical microscope and scanning electron microscope observations verified the successful formation of the sensing structure and the cavity beneath the sensing elements. The sensor was experimentally characterized under magnetic fields ranging from −300 to 300 mT. The measured results exhibited excellent linearity over the entire measurement range. The sensor achieved a measured sensitivity of 120 mV/T. Owing to its high sensitivity, simple fabrication process, and full compatibility with standard CMOS technology, the magnetic field sensor is promising for integrated microsystems, industrial monitoring, and intelligent sensing applications. Full article

The rapid electrification of transportation has accelerated the demand for high-power electric vehicle (EV)-charging systems with high efficiency, compact size, galvanic isolation, and flexible scalability. Conventional isolated EV chargers typically adopt cascaded AC–DC and DC–DC conversion stages, which require additional semiconductor devices, passive components, and bulky dc-link capacitors, thereby increasing system complexity and limiting power density. This paper proposes a scalable three-phase modular parallel quasi-single-stage isolated single-ended primary-inductor converter (SEPIC) for high-power EV fast-charging applications. The proposed converter integrates power factor correction, voltage regulation, and high-frequency isolation within a unified SEPIC-based conversion cell, eliminating the intermediate dc-link capacitor while reducing the number of magnetic components and power conversion stages. By employing a Δ-connected three-phase input and input/output-parallel modular configuration, the proposed architecture provides a flexible power expansion approach based on a 9 kW basic module, with the potential to extend to higher power levels, such as 54 kW, through paralleling multiple identical modules. The operating principle, steady-state characteristics, continuous conduction mode (CCM)/discontinuous conduction mode (DCM) transition mechanism, current-sharing behavior, and control strategy are systematically investigated. An 18 kW prototype consisting of two parallel modules is experimentally validated under 380 V three-phase AC input and 400 V DC output conditions. The experimental results demonstrate a peak efficiency of 97.5%, a rated efficiency of 97.3%, a power factor (PF) of 0.999, and an input current total harmonic distortion (THD) of 2.55%, confirming the effectiveness and scalability of the proposed converter for high-power EV fast-charging applications. Full article

Road traffic surveys require sensing systems that can be deployed rapidly without modifying the road surface or requiring a permanent power connection. This paper presents the design, embedded implementation, and evaluation of a low-power roadside magnetic sensor that performs vehicle-event detection and classification directly at the edge. The sensing node integrates two RM3100 three-axis magnetometers (PNI Sensor, Santa Rosa, CA, USA) with an NXP MK22FN512VLH12 microcontroller (NXP Semiconductors N.V., Eindhoven, The Netherlands) based on a 120 MHz Arm Cortex-M4F core with 512 kB Flash and 128 kB SRAM. Magnetic-field data are acquired at 250 Hz and processed locally using baseline removal, low-pass filtering, signal-energy calculation, and peak-based event detection. Detected magnetic signatures are classified using an integer-quantised one-dimensional convolutional neural network implemented directly on the microcontroller. The model processes four synchronised 512-sample channels representing the three magnetic-field axes and their combined signal energy. Model development was supported by approximately 50,000 annotated events obtained from 36 h of real-world traffic measurements at eight locations. The selected model achieved an overall classification accuracy of 91.1% for the considered operational categories. The implemented network requires 288,128 multiply–accumulate operations per inference, while its quantised weights and biases occupy approximately 23 kB of Flash memory. Complete three-axis event signatures are stored locally for subsequent verification, whereas only the timestamp and predicted vehicle category are transmitted through the wireless interface. Based on the capacity of the applied LiFePO₄ battery and the estimated consumption of the implemented hardware, the expected autonomous operating period is approximately 41 days. The results demonstrate the feasibility of integrating magnetic sensing, embedded signal processing, and Edge AI on a conventional resource-constrained Cortex-M4 platform for non-invasive road traffic monitoring. Full article

Multiferroic composite semiconductor fibers enable non-contact magnetic control but may also operate under spatially nonuniform thermal conditions. This study develops a one-dimensional analytical model for a symmetric CoFe₂O₄/ZnO/CoFe₂O₄ fiber subjected to local magnetic and temperature fields with independently prescribed widths. The model combines piezomagnetic, piezoelectric, pyroelectric, thermoelastic, and semiconductor effects and provides closed-form solutions for the electric potential, electric field, polarization, and electron concentration perturbation. Local magnetic and thermal inputs generate localized potential barriers and wells through distinct pathways. Where the excitation regions overlap, their contributions may reinforce, compete with, or partially cancel each other. The initial electron concentration affects the carrier-screening strength and spatial localization of the electrical response, whereas the layer-thickness ratio influences the competition between piezomagnetic actuation and piezoelectric conversion. An independent finite-element calculation closely reproduces the analytical potential distribution for the baseline case. This study clarifies the interaction between the magnetic and thermal contributions to open-circuit carrier redistribution and provides a field-distribution baseline for future biased, contact-resolved transport analyses of multiferroic micro- and nanostructures. Full article

Early warning has been widely proven to be reliable in lowering the risk of instability for biological processes. However, it is very difficult for the warning systems used currently to achieve satisfactory accuracy, timeliness and universality simultaneously. This study developed a novel early warning system for instability in food waste anaerobic digestion (FWAD) by bioimitating the human disease screening paradigm. It consists of single, comprehensive and microbiological indicators. Findings showed that single-factor early warning systems resembled acute patient diagnosis, having high accuracy but low timeliness and poor universality. Each of the chosen single indicators showed distinct early warning performances and clear preferences for diverse inhibitions concerning the instabilities of high organic load rate, high ammonia, and high fat in FWAD. Then, a new comprehensive indicator was developed using the entropy weights of several indicators. Confirmatory tests revealed that the comprehensive indicator-based early warning system was analogue to the resident sub-health diagnostic regarding superior foresight and good operability but poor targeting. Therefore, an early warning system based on microbial changes was proposed for potential instability in FWAD by bioimitating human periodic physical examination. The sensitive bacteria were identified as norank_o_ norank_c_Dojkabacteria and Rikenellaceae_RC9_gut_group. Enlarged tests showed that the developed system could be used for emergent, indistinct and potential early warnings simultaneously while avoiding the shortcomings of existing systems. More preciously, this study provided a paradigm for developing early warning systems of FWAD, which is also suitable to be applied to the intelligent systems that rely on automated machine learning. Full article

Light detection and ranging (LiDAR) systems are pivotal for precise distance and velocity measurement, yet widespread deployment requires solutions that balance their performance, robustness, and simplicity. Here, we propose a novel chaotic LiDAR system based on a semiconductor vertical-cavity surface-emitting laser (VCSEL) with delayed orthogonal polarization feedback. By exploiting the intrinsic competition between the transverse electric (TE) and transverse magnetic (TM) modes, the system generates polarization-multiplexed dynamics: a chaotic TM mode serves as the reference, while a feedback-modulated TE mode probes the target. This all-in-one source eliminates the need for external optical modulators or complex coherent detection. The system’s dynamics are finely tunable via a half-wave ($\lambda$/2) plate in the feedback loop and the laser injection current, enabling real-time optimization of the cross-correlation signal-to-noise ratio. Experimental results demonstrate precise linear ranging with a resolution of approximately 1.2 cm. Furthermore, the system exhibits strong inherent resistance to external optical interference, maintaining accurate ranging even in the presence of a secondary laser source. This compact, tunable, and interference-resilient platform offers a promising pathway toward low-cost, high-performance LiDAR for applications in autonomous navigation, robotics, and industrial metrology. Full article

This paper presents the integrated design and experimental verification of a ferrite spoke permanent magnet motor with rib core skew for semiconductor process pump drives. Conventional induction motors are widely used in industrial pump systems because of their robustness and cost-effectiveness; however, rotor copper loss and limited output capability under a restricted installation envelope remain practical limitations. To address these issues without rare-earth magnets, a flux-concentrating ferrite spoke rotor is applied. The proposed design procedure considers the baseline induction motor envelope, electric and magnetic loadings, manufacturable winding specifications, voltage and current density limits, irreversible demagnetization, and post-assembly magnetization feasibility. An 8-pole/12-slot topology is selected because it enables one-shot post-assembly magnetization, unlike the 10-pole/12-slot alternative requiring segmented magnetization. Rib core skew and stator tooth shoe chamfer geometries are then applied to reduce cogging torque and load torque ripple. A prototype is fabricated and tested. At 1000 rpm, the measured no-load line-to-line voltage is 21.6 V_rms. At 7000 rpm, the prototype achieves 4.028 kW output power and 93.1% efficiency. The measured post-assembly magnetization ratio is 98.7%, and the maximum winding temperature recorded during an approximately 50 min water-cooled test at 6.68 A/mm² is 57.4 °C. These results confirm the feasibility of the proposed design procedure. Full article

The chiral interaction between light and matter is intrinsically weak at the nanoscale, which leads to a sensitivity bottleneck in the detection of chiral samples by photoinduced force microscopy. To address this issue, we propose an enhancement strategy that combines a semiconductor tip with a superchiral optical field to improve the optical force response in nanoscale chiral detection. Compared with a conventional metallic tip, a silicon tip can generate a larger optical force difference under left- and right-handed circularly polarized illumination. This enhancement mainly arises from the more pronounced magnetic response of the silicon tip, which increases the contribution of the magnetic dipole term to the total optical force. Furthermore, when the incident field is changed from a circularly polarized field to a superchiral field, the optical force difference acting on the same tip can be further increased by more than one order of magnitude. Relative to the reference case of a gold tip excited by circularly polarized light, the combination of a superchiral field and a silicon tip enhances the optical force difference by nearly two orders of magnitude. Analysis based on the dipole approximation shows that this enhancement originates from the synergistic effect of two factors: the high-refractive-index silicon tip provides a stronger magnetic response, while the superchiral field further strengthens the coupling between the localized chiral field and the tip and effectively excites the magnetic dipole and electromagnetic coupling terms, thereby jointly amplifying the chiral optical force signal. This work provides a new route for the highly sensitive detection of chiral materials at the nanoscale and may further extend the applications of photoinduced force microscopy in the characterization of chirality and optomagnetic interactions. Full article

Ferroelectric field-effect transistors, which rely on ferroelectric polarization reversal to modulate the channel resistance, hold great promise for nonvolatile memory and neuromorphic computing. The polarization switching dynamics are critical for achieving high-speed, high-bit-density neuromorphic hardware. Here, we report a 1D-2D asymmetric heterojunction composed of a single-element tellurium (Te) nanowire and a magnetic metal, Fe₃GaTe₂. Piezoresponse force microscopy reveals reversible polarization switching at room temperature. Utilizing this ferroelectric heterojunction, we construct ferroelectric semiconductor field-effect transistors that exhibit tunable resistance states exceeding 7 bits, featuring an on/off ratio of 10³, a retention time exceeding 10³ s, and ultrafast switching down to 20 ns. Moreover, the transistor enables accurate recognition of six kinds of micro-defects with an accuracy of 97.1% on the workpiece surface by convolutional neural network. This work establishes the intrinsic relationship between ferroelectric polarization and resistance modulation, providing a device platform for next-generation multilevel storage and ultrafast neuromorphic computing networks. Full article

We present a first-principles investigation of the layered ternary manganese tellurides ${\mathrm{MgMnTe}}_2$, ${\mathrm{Mg}}_3{\mathrm{MnTe}}_4$, and ${\mathrm{MgMn}}_3{\mathrm{Te}}_4$ using density functional theory with GGA and meta-GGA functionals. The optimized tetragonal structures (space group No. 115) satisfy the Born elastic stability criteria, with the structural derivatives exhibiting enhanced ductility. Unlike analogous alkali-based half-metals, these systems emerge as ferromagnetic semiconductors featuring substantial energy gaps in both spin channels. The calculated total spin magnetic moments are strict integers ($5 {\mathrm{\mu }}_{\mathrm{B}}$ for ${\mathrm{MgMnTe}}_2$ and ${\mathrm{Mg}}_3{\mathrm{MnTe}}_4$; $15 {\mathrm{\mu }}_{\mathrm{B}}$ for ${\mathrm{MgMn}}_3{\mathrm{Te}}_4$), driven predominantly by localized Mn d-states. Although advanced meta-GGA functionals modulate the magnitude of the predicted band gaps, the overarching electronic topology and magnetic character remain highly consistent. Ultimately, their calculated elastic response and intrinsic ferromagnetic semiconducting behavior identify these phases as candidates for further theoretical and experimental investigation for spintronic applications. Full article

This paper presents a two-dimensional magneto-photo-thermoelastic model for a fiber-reinforced anisotropic semiconductor half-space subjected to optical excitation and a variable gravity field. The formulation is developed within the framework of generalized photo-thermoelasticity by considering the coupled interactions among thermal, elastic, carrier-density, electromagnetic, and gravity-induced effects. The constitutive equations of a fiber-reinforced anisotropic medium are employed, while the influences of the magnetic field and gravity are incorporated into the governing equations. A suitable nondimensionalization procedure is introduced, and the resulting coupled system is solved analytically using the normal mode technique and eigenvalue approach. Numerical results are obtained for the temperature, carrier density, displacement components, and stress distributions. The influence of the gravity parameter on the physical fields is investigated in detail. The results indicate that gravity significantly affects the mechanical and stress responses, whereas its effect on the thermal and carrier-density fields is comparatively less pronounced. A comparative study between silicon and germanium semiconductors is also carried out, revealing noticeable differences in the amplitudes and attenuation behavior of the coupled fields due to variations in material properties. The present study provides useful insights into coupled multiphysical interactions in semiconductor structures and may be relevant to applications in optoelectronic devices, photonic systems, smart composite materials, and aerospace technologies. Full article

Two-dimensional (2D) intrinsic ferromagnets with perpendicular magnetic anisotropy (PMA) have been experimentally verified as promising candidates for nanoscale spintronic devices and magnetic random-access memories. In this work, we systematically investigate the stability, electronic structure, and magnetic properties of monolayer MOCl (M = Ti, V, Cr, Mo) via first-principles calculations. The results demonstrate that allshi ciju monolayers MOCl (M = Ti, V, Cr, Mo) are intrinsic ferromagnetic semiconductors, with magnetic moments of 1.0 μ_B/Ti atom, 2.0 μ_B/V atom, 2.5 μ_B/Cr atom and 3.0 μ_B/Mo atom, respectively. Notably, both monolayers TiOCl and CrOCl exhibit perpendicular magnetic anisotropic energy (MAE), which is mainly contributed by metal atoms Ti and Cr, respectively. Drawing on the second-order perturbation theory, we conduct an analysis of the density of states and the magnetic anisotropy energy (MAE) resolved by d orbitals for Ti and Cr atoms. Our analysis shows that in monolayer TiOCl, the MAE of Ti atoms mainly stems from the disparities in matrix elements between the d_yz and d_x²−y² (d_xz) orbitals. Conversely, in monolayer CrOCl, the MAE of Cr atoms is largely due to the differences in matrix elements between the d_xy (d_yz) and d_x²−y² (d_z²) orbitals. Biaxial strain can efficiently regulate the MAE of monolayer CrOCl. Specifically, when under tensile strain, the MAE of monolayer CrOCl experiences a substantial increase. Our research results indicate that both monolayers TiOCl and CrOCl have significant potential for use in spintronic devices and high-density data storage systems. Full article