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Observation and mitigation of dimensional resonance in thick electroinfiltrated nanocomposites

Journal of Magnetism and Magnetic materials 2025年 627卷

作者： Amirisetti, Sai Pranesh Smith, Connor S. Mills, Sara C. Andrew, Jennifer S. Arnold, David P. Department of Electrical and Computer Engineering University of Florida GainesvilleFL32611 United States Department of Materials Science and Engineering University of Florida GainesvilleFL32611 United States

Magnetic nanocomposites have applications in power electronics, where properties such as high permeability, high film thickness, high operating frequency, and low loss are desired. Recent work shows that electroinfiltration, where a magnetic composite is formed by electroplating a metal through a deposited nanoparticle layer, produces magnetic composites with high permeabilities and low losses. However, electroinfiltration of single layers has so far been limited to film thicknesses ≤4μm. Thicker films have been achieved by successive deposition of composite layers, but material measurements reveal a trade-off between composite thickness and maximum operating *** trade-off is attributed to dimensional resonance, caused by the formation of standing waves in the material cross-section. Laminations with electrically insulating interlayers can be used to overcome this effect, since the resulting laminated layers have smaller cross-sections that increase the frequency at which standing waves begin to form. This work demonstrates a process to create thick magnetic composites by laminating layers of infiltrated magnetic composite with insulating layers of either parylene or silicon dioxide to reduce dimensional resonance effects. Iron-oxide nanoparticles infiltrated with nickel are used. Four samples are made, containing 1, 2, 3, and 5 layers of magnetic composite, separated from each other by approximately 1–2.5 μm of parylene or 100 nm of SiO2. Structural characterization of these samples using SEM with EDS capabilities shows that the desired laminated structures were ***, DC magnetic characterization shows that the magnetic saturation of the material decreases due to the introduction of the non-magnetic laminations. Finally, AC magnetic measurements reveal that the laminated composites have a constant dimensional resonance of approximately 350 MHz, irrespective of the number of layers and total film *** conclusion is that laminating the na

关键词： Nanocomposite films

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Microwave-induced cooling in double quantum dots: Achieving millikelvin temperatures to reduce thermal noise around spin qubits

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Physical Review B 2025年第1期111卷 014305-014305页

作者： Daryoosh Vashaee Jahanfar Abouie Department of Materials Science and Engineering and Department of Electrical and Computer Engineering North Carolina State University Raleigh North Carolina 27606 USA Department of Physics Institute for Advanced Studies in Basic Sciences Zanjan 45137-66731 Iran

Spin qubits in gate-defined quantum dots are emerging as a leading technology due to their scalability and long coherence times. However, maintaining these qubits at ultralow temperatures typically requires complex cryogenic systems. This paper proposes a gate-defined double quantum dot (DQD) cooling system, where the DQDs act as refrigerants to reduce the local phonon environment around computational qubits. The cooling process occurs in two distinct stages: the first step involves microwave-induced state depopulation combined with fast cyclic detuning to transfer the DQD's population to the ground state, effectively lowering the DQD's temperature. In the second step, the cooled DQD interacts with and absorbs phonons resonant with the DQD spin energy, thereby filtering out these phonons that contribute to spin-lattice relaxation in the surrounding environment. This study focuses on the first step, presenting detailed calculations and numerical results that demonstrate the feasibility of achieving local DQD temperatures below 10mK at a bath temperature of 1K. The sensitivity of the cooling performance to detuning energy, magnetic field strength, spin-orbit couplings, and diabatic return time is analyzed, while the phonon filtering in the second step will require further investigation.

关键词： Semiconductor quantum dots

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Analysis of Partial Discharges in Oil-Impregnated Transformer Paper Insulation and PET-G Insulation

IEEE Open Journal of Instrumentation and Measurement

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IEEE Open Journal of Instrumentation and Measurement 2025年 4卷

作者： Kameli, Sayed Mohammad Abuelrub, Abdelaziz AlShaikh Saleh, Mohammad Refaat, Shady S. Ghrayeb, Ali Abu-Rub, Haitham Olesz, Marek Texas A&M University at Qatar Electrical and Computer Engineering Department Doha Qatar Texas A&M University Department of Electrical and Computer Engineering College StationTX77843 United States University of Hertfordshire School of Physics Engineering and Computer Science Department of Engineering HatfieldAL10 9EU United Kingdom Hamad Bin Khalifa University Qatar Foundation Electrical and Computer Engineering Program in College of Science and Engineering Doha Qatar Gdańsk University of Technology Department of Electrical Power Engineering Gdańsk80-233 Poland

Partial discharge (PD) is a widespread phenomenon instigated in power transformer (PT) insulation systems. PDs are triggered by voids that vary in size and position within the PT insulation. The electrical characteristics of those damaging, PD-causing cavities must be well understood, to accelerate the development of advanced PD detection techniques. Thus, the impact of varying the radius and position of spherical air voids on the characteristics of PDs in PTs is examined using a 3-D finite element analysis (FEA) model designed in COMSOL Multiphysics. The spherical voids are positioned between two windings of a 512 kV, three-phase (3φ ) PT. The peak electric field (EF) and aggregate energy in the FEA model are used in conjunction with laboratory measurements of the apparent discharge magnitude, for detailed analysis of Polyethylene Terephthalate Glycol (PET-G)-based cylindrical voids with different heights. Simulations demonstrate that the inception of PD activity in the PT model occurs for spherical voids with a radius exceeding 1 mm. Furthermore, the most severe PDs occur within the press-board insulation, adjacent to the uppermost part of the innermost windings. Experiments demonstrate that a significant increase in PD activity was observed for PET-G-based cylindrical voids with heights exceeding 1 mm. © 2022 IEEE.

关键词： Partial discharges

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Micromagnetic Simulations of Concentration Detection Capability of Large-Area and Low-Aspect-Ratio GMR Sensors in Biomedical Diagnostics

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IEEE Transactions on Magnetics 2025年

作者： Mendonsa, Riyan Liang, Shuang Tonini, Denis Wang, Jian-Ping University of Minnesota Department of Electrical and Computer Engineering MinneapolisMN55455 United States University of Minnesota Department of Chemical Engineering and Materials Science MinneapolisMN55455 United States

Since the discovery of Giant Magnetoresistance(GMR), it has found many applications in sensors. One of these key areas is for biomedical sensing. GMR biosensors with large-area and low-aspect-ratio were demonstrated experimentally with ultra high sensitivity, followed by a relatively simplified theoretical explanation. This study presents a systematic micromagnetic simulation analysis of large-area and low-aspect-ratio GMR sensors, with a particular focus on two key regimes: the linear portion before saturation by the magnetic nanoparticle(MNP) interaction with the sensor and the flattening out due to sensor saturation. This study presents a simulation-based analysis of large-area and low-aspect-ratio GMR sensors using micromagnetic simulations for biomedical diagnostic applications. We investigate various MNP types and sizes. Through systematic simulations, we compare sensitivity to concentration and highlight the influence of MNP characteristics and concentration on the large-area GMR sensor's performance. This study not only furthers the understanding of large-area and low-aspect-ratio GMR sensor behavior, but also paves the way for future targeted experimental research and development in this promising field. © 1965-2012 IEEE.

关键词： Aspect ratio

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Ultrastable supported oxygen evolution electrocatalyst formed by ripening-induced embedding

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science (New York, N.Y.) 2025年第6735期387卷 791-796页

作者： Shi, Wenjuan Shen, Tonghao Xing, Chengkun Sun, Kai Yan, Qisheng Niu, Wenzhe Yang, Xiao Li, Jingjing Wei, Chenyang Wang, Ruijie Fu, Shuqing Yang, Yong Xue, Liangyao Chen, Junfeng Cui, Shiwen Hu, Xiaoyue Xie, Ke Xu, Xin Duan, Sai Xu, Yifei Zhang, Bo State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular Science Fudan University Shanghai China Collaborative Innovation Center of Chemistry for Energy Materials Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials MOE Key Laboratory of Computational Physical Sciences Department of Chemistry Fudan University Shanghai China Department of Chemistry and Department of Electrical and Computer Engineering Northwestern University Evanston IL United States Hefei National Laboratory Hefei China

The future deployment of terawatt-scale proton exchange membrane water electrolyzer (PEMWE) technology necessitates development of an efficient oxygen evolution catalyst with low cost and long lifetime. Currently, the stability of the most active iridium (Ir) catalysts is impaired by dissolution, redeposition, detachment, and agglomeration of Ir species. Here we present a ripening-induced embedding strategy that securely embeds the Ir catalyst in a cerium oxide support. Cryogenic electron tomography and all-atom kinetic Monte Carlo simulations reveal that synchronizing the growth rate of the support with the nucleation rate of Ir, regulated by sonication, is pivotal for successful synthesis. A PEMWE using this catalyst achieves a cell voltage of 1.72 volts at a current density of 3 amperes per square centimeter with an Ir loading of just 0.3 milligrams per square centimeter and a voltage degradation rate of 1.33 microvolts per hour, as demonstrated by a 6000-hour accelerated aging test.

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PCM-based Silicon Photonic Neural Networks under Fabrication Nonuniformity 6

PCM-based Silicon Photonic Neural Networks under Fabrication...

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AI and Optical Data sciences VI 2025

作者： Shafiee, Amin Ghanaatian, Zahra Charbonnier, Benoit Rios, Carlos Pasricha, Sudeep Nikdast, Mahdi Department of Electrical and Computer Engineering Colorado State University Fort CollinsCO80523 United States Université Grenoble Alpes CEA-Leti GrenobleF38000 France Department of Materials Science & Engineering University of Maryland College ParkMD20742 United States

ISBN: (纸本)9781510684980

In this paper, we analyze optical phase noise due to fabrication process imperfections in the phase change materials’s (PCMs) width and thickness. To highlight the effect of accumulated phase noise due to variations at the system level, we consider a case study of coherent MZI-based silicon photonic neural networks utilizing PCM-based phase shifters. The simulation results show that in the absence of any pre- or post-fabrication correction methods, the scalability of the system will be extremely limited (up to N =16) with significant accuracy drop of about 85%. © 2025 SPIE.

关键词： Silicon photonics

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Probability Mass Function of Energy for Light-Collecting Surfaces in Rough Geometries and Its Applications in Urban Energy and Photovoltaics

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IEEE Journal of Photovoltaics 2025年

作者： Ziar, Hesan Delft University of Technology Photovoltaic Materials and Devices Group Department of Electrical Sustainable Energy Faculty of Electrical Engineering Mathematics and Computer Science Delft2628 Netherlands

Sunlight throughout urban areas largely impacts local climate [sustainable development goal (SDG) 13], residents’ well-being (SDG 3), and access to clean energy (SDG 7). However, sunlight availability on various urban surfaces is affected by urban geometry. Here, in this work, a probabilistic framework to evaluate the interplay between sunlight and urban geometry is presented, and its immediate applications in urban energy studies are demonstrated. A probability mass function that predicts the energy production of a group of light-collecting surfaces, such as solar photovoltaic (PV) systems, installed in rough geometries, such as urban areas, is derived. Along the way, an expression for the sky view factor (SVF) is formulated within rough geometries as well as a link between the capacity factor of the residential PV fleet and urban geometry. The predictions of the mathematical framework are validated using the digital surface model and collected PV systems data in The Netherlands. This work primarily helps understand the underlying relation between the geometrical parameters of a rough surface and the received sunlight energy on a subset of that surface. Exemplified applications are swift SVF calculations and residential PV fleet yield predictions, which, respectively, support efficient urban energy assessments and privacy-preserving electrical grid management. © 2011-2012 IEEE.

关键词： Normal distribution

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electrical and structural characterization of in situ MOCVD Al2O3/β-Ga2O3 and Al2O3/β-(AlxGa1−x)2O3 MOSCAPs

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Journal of Applied Physics 2025年第17期137卷

作者： Bhuiyan, A. F. M. Anhar Uddin Meng, Lingyu Yu, Dong Su Dhara, Sushovan Huang, Hsien-Lien Vangipuram, Vijay Gopal Thirupakuzi Hwang, Jinwoo Rajan, Siddharth Zhao, Hongping Department of Electrical and Computer Engineering The Ohio State University ColumbusOH43210 United States Department of Electrical and Computer Engineering University of Massachusetts Lowell LowellMA01854 United States Department of Materials Science and Engineering The Ohio State University ColumbusOH43210 United States

This study investigates the electrical and structural properties of metal-oxide-semiconductor capacitors (MOSCAPs) with in situ metal-organic chemical vapor deposition-grown Al2O3 dielectrics deposited at varying temperatures on (010) β-Ga2O3 and β-(AlxGa1−x)2O3 films with different Al compositions. The Al2O3/β-Ga2O3 MOSCAPs exhibited a strong dependence of electrical properties on Al2O3 deposition temperature. At 900 °C, reduced voltage hysteresis (∼0.3 V) with improved reverse breakdown voltage (74.5 V) was observed, corresponding to breakdown fields of 5.01 MV/cm in Al2O3 and 4.11 MV/cm in β-Ga2O3 under reverse bias. In contrast, 650 °C deposition temperature resulted in higher voltage hysteresis (∼3.44 V) and lower reverse breakdown voltage (38.8 V) with breakdown fields of 3.69 and 2.87 MV/cm in Al2O3 and β-Ga2O3, respectively, but exhibited impressive forward breakdown field, increasing from 5.62 MV/cm at 900 °C to 7.25 MV/cm at 650 °C. High-resolution scanning transmission electron microscopy (STEM) revealed improved crystallinity and sharper interfaces at 900 °C, contributing to enhanced reverse breakdown performance. For Al2O3/β-(AlxGa1−x)2O3 MOSCAPs, increasing Al composition (x) from 5.5% to 9.2% reduced net carrier concentration and improved reverse breakdown field contributions from 2.55 to 2.90 MV/cm in β-(AlxGa1−x)2O3 and 2.41 to 3.13 MV/cm in Al2O3. The electric field in Al2O3 dielectric under forward bias breakdown also improved from 5.0 to 5.4 MV/cm as Al composition increased from 5.5% to 9.2%. The STEM imaging confirmed the compositional homogeneity and excellent stoichiometry of both Al2O3 and β-(AlxGa1−x)2O3 layers. These findings demonstrate the robust electrical performance, high breakdown fields, and excellent structural quality of Al2O3/β-Ga2O3 and Al2O3/β-(AlxGa1−x)2O3 MOSCAPs, highlighting their potential for high-power electronic applications. © 2025 Author(s).

关键词： Metallorganic chemical vapor deposition

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Highly Elliptic Circular Dichroism of Copper Aspartate One-Dimensional Nanostructures across the Ultraviolet to Terahertz Ranges

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Nano Letters 2025年第19期25卷 7699-7706页

作者： Choi, Won Jin Kim, Ji-Young Hwang, Myonghoo Lim, Chung Man Park, Bum Chul Emre, Ahmet Lee, Sang Hyun Kotov, Nicholas A. Department of Chemical Engineering University of Michigan Ann ArborMI48109 United States Biointerfaces Institute University of Michigan Ann ArborMI48109 United States Physical Life and Sciences Lawrence Livermore National Laboratory LivermoreCA94550 United States Department of Chemical and Biological Engineering Rensselaer Polytechnic Institute TroyNY12180 United States Center for Biotechnology and Interdisciplinary Studies Rensselaer Polytechnic Institute TroyNY12180 United States Department of Materials Science and Engineering University of Michigan Ann ArborMI48109 United States University of Michigan Ann ArborMI48109 United States Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109 United States

Since the discovery of chirality, circular dichroism (CD) of mirror-asymmetric molecules has been studied across the ultraviolet, visible, and near-infrared ranges. Recently, chiroptical activity studies have expanded to the terahertz (THz) range, where resonance peaks originate from collective vibrations of tens and hundreds of atoms. In this study, we synthesized Cu2+ coordination complexes with L- and D-aspartic acid as nanowires and nanorods and characterized their chiroptical activity across multiple frequency ranges. Both chiral nanostructures exhibit strong electronic CD (ECD), primarily from Cu2+ d-d transitions, while vibrational CD (VCD) spectra show sharp C=O, C-H, and O-H vibronic peaks, indicating higher atomic defect densities in nanorods than nanowires. Although THz CD (TCD) spectra are broad, they exhibit ∼1000× greater ellipticity than ECD and VCD, perhaps warranting previous references to circular dichroism of nanostructures as giant. Comparative TCD analysis highlights strong chiral phonon sensitivity, underscoring its potential for probing defect densities and structural changes for various chiral nanostructures and (bio)crystals. © 2025 American Chemical Society.

关键词： Terahertz spectroscopy

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Photon-magnon coupling using gain-assisted spoof-localized surface plasmons

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Optics Express 2025年第8期33卷 16809-16819页

作者： Xiong, Yuzan Christy, Andrew Li, Yi Sun, Rui Comstock, Andrew H. Wu, Junming Lopez, Rene Lei, Sidong Sun, Dali Cahoon, James F. Zhang, Xufeng Yang, Binbin Zhang, Wei Department of Physics and Astronomy University of North Carolina at Chapel Hill Chapel HillNC27599 United States Department of Chemistry University of North Carolina at Chapel Hill Chapel HillNC27599 United States Materials Science Division Argonne National Laboratory ArgonneIL60439 United States North Carolina State University RaleighNC27695 United States NanoScience Technology Center University of Central Florida OrlandoFL32826 United States Department of Material Science and Engineering University of Central Florida OrlandoFL32816 United States Department of Electrical and Computer Engineering Northeastern University BostonMA02115 United States Department of Physics Northeastern University BostonMA02115 United States Department of Electrical and Computer Engineering North Carolina A&T State University GreensboroNC27411 United States

Improving the photon-magnon coupling strength can be done by tuning the structure of microwave resonators to better interact with the magnon counterpart. Planar resonators accommodating unconventional photon modes beyond the half- and quarter-wavelength designs have been explored due to their optimized mode profiles and potentials for on-chip integration. Here, we designed and fabricated an actively controlled ring resonator supporting the spoof localized surface plasmons (LSPs), and implemented it in the investigation of photon-magnon coupling for hybrid magnonic applications. We demonstrated gain-assisted photon-magnon coupling with the YIG magnon mode under several different sample geometries. The achieved coupling amplification largely benefits from the high quality factor (Q-factor) due to the additional gain provided by a semiconductor amplifier, which effectively increases the Q-factor from a nearly null state (passive resonance) to more than 1000 for a quadrupole LSP mode. Our results suggest an additional control knob for manipulating photon-magnon coupled systems exploiting external controls of gain and loss. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词： Q factor measurement

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