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SSRN 2023年

作者： Rogers, Ariel He, Zhiyao Wang, Yong Department of Physics University of Arkansas FayettevilleAR72701 United States Department of Computer Science and Computer Engineering University of Arkansas FayettevilleAR72701 United States Materials Science & Engineering Program University of Arkansas FayettevilleAR72701 United States Cell & Molecular Biology Program University of Arkansas FayettevilleAR72701 United States

An interesting connection between shark spiral intestines and the Tesla valve was proposed recently;however, how Tesla valves interact with active matters and the potential applications of Tesla valves in biology remain largely unexplored. Here, we present a computational study on the potential use of Tesla valves for filtering and sorting microscale active swimmers such as bacteria. We investigated the behavior of microswimmers passing through the Tesla valve at different linear and angular velocities using numerical simulations, and quantified the diodicity of the Tesla valve for active swimmers. Our results demonstrate that the Tesla valve can effectively filter and sort microscale swimmers based on their swimming behavior. The findings of this study suggest that Tesla valves could have potential applications in microscale sorting and chromatography, with significant implications for biomedical and environmental engineering. © 2023, The Authors. All rights reserved.

关键词： Bacteria

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Entanglement in Quantum Dots: Insights from Dynamic Susceptibility and Quantum Fisher Information

arXiv

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arXiv 2024年

作者： Abouie, Jahanfar Vashaee, Daryoosh Department of Physics Institute for Advanced Studies in Basic Sciences Zanjan45137-66731 Iran Department of Materials Science & Engineering North Carolina State University RaleighNC27606 United States Department of Electrical & Computer Engineering North Carolina State University RaleighNC27606 United States

This study investigates the entanglement properties of quantum dots (QDs) under a universal Hamiltonian where the Coulomb interaction between particles (electrons or holes) decouples into charging energy and exchange coupling terms. Although this formalism typically decouples the charge and spin components, confinement-induced energy splitting can induce unexpected entanglement within the system. By analyzing the dynamic susceptibility and quantum Fisher information (QFI), we uncover significant behaviors influenced by exchange constants, temperature variations, and confinement effects. In QDs with Ising exchange interactions, far below the Stoner instability (SI) point, where the QD is in a disordered paramagnetic phase, temperature reductions lead to decreased entanglement, challenging conventional expectations. Our findings demonstrate that for QDs with small exchange interactions, the responses of easy-plane (Jz ⊥) and easy-axis (Jz > J⊥) configurations are similar, with increased anisotropy broadening susceptibility and shifting its maximum to higher frequencies. For large exchange interactions, the susceptibility differences between easy-plane and easy-axis QDs become significant, with easy-plane QDs exhibiting a higher susceptibility magnitude. Additionally, the study reveals that temperature variations affect the dynamic response functions differently in easy-axis and easy-plane QDs. In easy-plane QDs, QFI consistently decreases with increasing temperature, whereas in easy-axis QDs, QFI behavior is highly dependent on the strengths of Jz and J⊥, showing either an increase or decrease with temperature based on specific coupling conditions. Conversely, at low temperatures, anisotropic Heisenberg models exhibit enhanced entanglement near isotropic points. Overall, this work contributes to advancing our understanding of entanglement in QDs and its potential applications in quantum technologies. Copyright © 2024, The Authors. All rights reserved.

关键词： Anisotropy

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Eigenvalue-Based Micromagnetic Analysis of Switching in Spin-Torque-Driven Structures

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Physical Review Applied 2022年第3期17卷 034016-034016页

作者： Z. Lin I. Volvach X. Wang V. Lomakin Department of Electrical and Computer Engineering University of California San Diego La Jolla California 92093 USA Center for Memory and Recording Research La Jolla California 92093 USA Materials Science and Engineering Program University of California San Diego La Jolla California 92093 USA

We present an eigenvalue-based approach for studying the magnetization dynamics in magnetic nanostructures driven by spintronic excitations, such as spin-transfer torque and spin-orbit torque. The approach represents the system dynamics in terms of normal oscillation modes (eigenstates) with corresponding complex eigenfrequencies. The dynamics is driven by a small number of active eigenstates and often considering just a single eigenstate is sufficient. We develop a perturbation theory that provides semianalytical dynamic solutions by using eigenstates for the case in the absence of damping and spintronic excitations as a basis. The approach provides useful insights into dynamics in such systems and allows solving several difficulties in their modeling, such as extracting the switching current in magnetic random-access memories and understanding switching mechanisms. We show that the presented approach directly predicts the critical switching current, i.e., switching current for an infinite time. The approach also provides solutions for the switching dynamics allowing the switching current to be obtained for a finite switching time, provided that the system symmetry is broken, e.g., by tilting the polarizer, so that switching by a finite pulse is possible.

关键词： Magnetization dynamics Spin transfer torque Spin-orbit torque Spintronics Devices for digital logic, storage & processing Landau-Lifschitz-Gilbert equation Micromagnetic modeling Perturbation theory

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HZO-based FerroNEMS MAC for In-Memory Computing

arXiv

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arXiv 2022年

作者： Jadhav, Shubham Gund, Ved Davaji, Benyamin Jena, Debdeep Xing, Huili Grace Lal, Amit School of Electrical and Computer Engineering Cornell University IthacaNY United States Department of Materials Science and Engineering Cornell University IthacaNY United States Electrical and Computer Engineering Department Northeastern University BostonMA United States

This paper demonstrates a hafnium zirconium oxide (HZO)-based ferroelectric NEMS unimorph as the fundamental building block for very low-energy capacitive readout in-memory computing. The reported device consists of a 250 μm × 30 μm unimorph cantilever with 20 nm thick ferroelectric HZO on 1 μm SiO2. Partial ferroelectric switching in HZO achieves analog programmable control of the piezoelectric coefficient (d31) which serves as the computational weight for multiply-accumulate (MAC) operations. The displacement of the piezoelectric unimorph was recorded by actuating the device with different input voltages Vin. The resulting displacement was measured as a function of the ferroelectric programming/poling voltage VP. The slopes of central beam displacement (δmax) vs Vinwere measured to be between 182.9nm/V (for -8Vp) and - 90.5nm/V (for 8Vp), demonstrating that Vpcan be used to change the direction of motion of the beam. The resultant δmaxfrom AC actuation is in the range of -18 to 36 nm and is a scaled product of the input voltage and programmed d31(governed by the Vp). The multiplication function serves as the fundamental unit for MAC operations with the ferroelectric NEMS unimorph. The displacement from many such beams can be added by summing the capacitance changes, providing a pathway to implement a multi-input and multi-weight neuron. A scaling and fabrication analysis suggests that this device can be CMOS compatible, achieving high in-memory computational throughput. © 2022, CC BY.

关键词： Silica

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Exciton-Exciton Interactions in Van der Waals Heterobilayers

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Physical Review X 2024年第3期14卷 031025-031025页

作者： Alexander Steinhoff Edith Wietek Matthias Florian Tommy Schulz Takashi Taniguchi Kenji Watanabe Shen Zhao Alexander Högele Frank Jahnke Alexey Chernikov Institut für Theoretische Physik Bremen Center for Computational Materials Science Institute of Applied Physics and Würzburg-Dresden Cluster of Excellence ct.qmat Department of Electrical Engineering and Computer Science Research Center for Materials Nanoarchitectonics Research Center for Electronic and Optical Materials Fakultät für Physik Munich Quantum Center and Center for NanoScience (CeNS) Munich Center for Quantum Science and Technology (MCQST) 80799 München Germany

Exciton-exciton interactions are key to understanding nonlinear optical and transport phenomena in van der Waals heterobilayers, which emerged as versatile platforms to study correlated electronic states. We present a combined theory-experiment study of excitonic many-body effects based on first-principle band structures and Coulomb interaction matrix elements. Key to our approach is the explicit treatment of the fermionic substructure of excitons and dynamical screening effects for density-induced energy renormalization and dissipation. We demonstrate that dipolar blueshifts are almost perfectly compensated by many-body effects, mainly by screening-induced self-energy corrections. Moreover, we identify a crossover between attractive and repulsive behavior at elevated exciton densities. Theoretical findings are supported by experimental studies of spectrally narrow, mobile interlayer excitons in atomically reconstructed, h-BN-encapsulated MoSe2/WSe2 heterobilayers. Both theory and experiment show energy renormalization on a scale of a few meV even for high injection densities in the vicinity of the Mott transition. Our results revise the established picture of dipolar repulsion dominating exciton-exciton interactions in van der Waals heterostructures and open up opportunities for their external design.

关键词： Excitons First-principles calculations Luminescence 2-dimensional systems Quantum many-body systems Many-body techniques

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Skin-like cryogel electronics from suppressed-freezing tuned polymer amorphization

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Nature Communications 2023年第1期14卷 1-10页

作者： Zhang, Xiansheng Yan, Hongwei Xu, Chongzhi Dong, Xia Wang, Yu Fu, Aiping Li, Hao Lee, Jin Yong Zhang, Sheng Ni, Jiahua Gao, Min Wang, Jing Yu, Jinpeng Ge, Shuzhi Sam Jin, Ming Liang Wang, Lili Xia, Yanzhi State Key Laboratory of Bio-Fibers and Eco-Textiles College of Textiles and Clothing Qingdao University Qingdao 266071 China Institute for Future Shandong Key Laboratory of Industrial Control Technology School of Automation Qingdao University Qingdao 266071 China College of Materials Science and Engineering Qingdao University Qingdao 266071 China CAS Key Laboratory of Engineering Plastics Institute of Chemistry Chinese Academy of Sciences Beijing 100190 China Department of Chemistry SungKyunKwan University Suwon 16419 South Korea State Key Laboratory of Fluid Power and Mechatronic Systems College of Mechanical Engineering Zhejiang University Hangzhou 310027 China College of Biological Science and Medical Engineering Donghua University Shanghai 201620 China Institute of Environmental Engineering ETH Zürich Zürich 8093 Switzerland Department of Electrical and Computer Engineering National University of Singapore Singapore 117576 Singapore

The sole situation of semi-crystalline structure induced single performance remarkably limits the green cryogels in the application of soft devices due to uncontrolled freezing field. Here, a facile strategy for achieving multifunctionality of cryogels is proposed using total amorphization of polymer. Through precisely lowering the freezing point of precursor solutions with an antifreezing salt, the suppressed growth of ice is achieved, creating an unusually weak and homogenous aggregation of polymer chains upon freezing, thereby realizing the tunable amorphization of polymer and the coexistence of free and hydrogen bonding hydroxyl groups. Such multi-scale microstructures trigger the integrated properties of tissue-like ultrasoftness (Young’s modulus <10 kPa) yet stretchability, high transparency (~92%), self-adhesion, and instantaneous self-healing (<0.3 s) for cryogels, along with superior ionic-conductivity, antifreezing (−58 °C) and water-retention abilities, pushing the development of skin-like cryogel electronics. These concepts open an attractive branch for cryogels that adopt regulated crystallization behavior for on-demand functionalities. © 2023, Springer Nature Limited.

关键词： Gels and hydrogels Polymers

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57 GHz Acoustic Resonator with k2 of 7.3 % and Q of 56 in Thin-Film Lithium Niobate

57 GHz Acoustic Resonator with k2 of 7.3 % and Q of 56 in Th...

引用

International Electron Devices Meeting (IEDM)

作者： Jack Kramer Sinwoo Cho Michael E. Liao Kenny Huynh Omar Barrera Lezli Matto Mark S. Goorsky Ruochen Lu Department of Electrical and Computer Engineering The University of Texas at Austin Austin TX USA Department of Materials Science & Engineering University of California Los Angeles CA USA

ISBN: (纸本)9781665489607

This paper reports an acoustic resonator at 57 GHz with a high electromechanical coupling $(k^{2})$ of 7.3% and 3-dB quality factor (Q) of 56, collectively enabling a record-breaking Figure of merit $(\mathrm{F}\mathrm{o}\mathrm{M},\ Q\cdot k^{2})$ of 4.1, an order of magnitude higher than the state-of-the-art acoustic resonators. The device leverages the third-order antisymmetric (A3) Lamb mode in 110 nm 128°Y-cut lithium niobate (LiNbO 3 ) piezoelectric thin film. A new film stack, namely transferred thin-film LiNbO 3 on sapphire substrate with an intermediate amorphous silicon (Si) layer, facilitates the record-breaking performance at millimeter-wave (mmWave). The acoustic resonator features a compact footprint of 0.006 $\mathrm{m}\mathrm{m}^{2}$. Acoustic design consideration is reported. The thickness of the $\mathrm{L}\mathrm{i}\mathrm{N}\mathrm{b}\mathrm{O}_{3}$ was measured with X-ray diffraction and verified with cross-sectional electron microscopy images. Triple-axis rocking curves confirm the $\mathrm{L}\mathrm{i}\mathrm{N}\mathrm{b}\mathrm{O}_{3}$ crystalline quality is higher than prior transferred $\mathrm{L}\mathrm{i}\mathrm{N}\mathrm{b}\mathrm{O}_{3}$ layers on Si. Upon further development, the reported platform can enable various signal processing functions at mmWave.

关键词： Radio frequency Q-factor Lithium niobate Resonator filters Resonant frequency X-ray diffraction Acoustics

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Integration of fullerenes and carbon nanotubes with aggressively scaled CMOS gate stacks

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MRS Online Proceedings Library 2021年第1期789卷 205-210页

作者： Udayan Ganguly Chungho Lee Edwin C. Kan Department of Materials Science and Engineering Cornell University USA School of Electrical and Computer Engineering Cornell University USA

Here we report the first study towards the integration of fullerenes and carbon nanotubes (CNT) in the gate stack of CMOS technology, which is a promising hybrid approach of top-down and bottom-up fabrication process. Prospective processes for C60 and CNT deposition over an aggressively scaled 2 nm gate oxide in the MOS capacitor structure have been monitored. CV measurements show minimal silicon contamination and interface states. Step charging at a specific voltage that corresponds to a fixed number density of C60 is used to establish the structural integrity and size-mono-dispersion of C60. The CV method can be further used to probe the charge injection into C60 and its anions to establish fundamental understanding of their molecular orbital (MO) structure.

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Deep Learning Approach for Classifying Contamination Levels with Limited Samples 27

Deep Learning Approach for Classifying Contamination Levels ...

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IS and T International Symposium on Electronic Imaging: 27th Color Imaging: Displaying, Processing, Hardcopy, and Applications, COLOR 2022

作者： Zhao, Min Diaz-Amaya, Susana Deering, Amanda J. Stanciu, Lia Chiu, George T.-C. Allebach, Jan P. School of Electrical and Computer Engineering Purdue University West LafayetteIN United States R&D|Sustainability & Outreach - Bayer at Convergence - Bayer Crop Science West LafayetteIN United States Department of Food Science Purdue University West LafayetteIN United States School of Materials Engineering Purdue University West LafayetteIN United States School of Mechanical Engineering Purdue University West LafayetteIN United States

The detection of the contaminants in daily food and drinking water is crucial for global public health. For heavy metals detection of Mercury (Hg) and Arsenic (As), our group has proposed a novel paper-based and microfluidic device integrated with a mobile phone and an image analysis pipeline to capture and analyze the sensor images on-site. Still, the detection of lower contamination levels remains challenging due to the small number of available data samples and large intra-class variance of our application. To overcome this challenge, we explore traditional data augmentation and GAN-based augmentation techniques for synthesizing realistic colorimetric images;and we propose a CNN classifier for five-contamination-levels classification. Our proposed system is trained and evaluated on a limited dataset of 126 phone captured images of five contamination levels. Our system yields 88.1% classification accuracy and 91.92% precision, demonstrating the feasibility of this approach. We believe that this approach of training deep learning models on limited detection images datasets presents a clear path toward phone-based contamination-levels detection. © 2022, Society for Imaging science and Technology.

关键词： Potable water

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Temperature-dependent perpendicular anisotropy and Gilbert damping of L10−FePd films: Role of noble-metal buffer layers

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Physical Review materials 2022年第11期6卷 113402-113402页

作者： Dingbin Huang Deyuan Lyu Xinjun Wang Michael B. Katz Delin Zhang Jian-Ping Wang Daniel B. Gopman Xiaojia Wang Department of Mechanical Engineering University of Minnesota Minneapolis Minnesota 55455 USA Minnesota Institute for Ultrafast Science University of Minnesota Minneapolis Minnesota 55455 USA Department of Electrical and Computer Engineering University of Minnesota Minneapolis Minnesota 55455 USA Department of Materials Science and Engineering University of Maryland College Park Maryland 20742 USA Materials Science and Engineering Division National Institute of Standards and Technology Gaithersburg Maryland 20899 USA

The moderate bulk perpendicular magnetic anisotropy (PMA, Ku≈1MJ/m3) and low Gilbert damping (α < 0.01) make L10-FePd a promising candidate for energy-efficient and nonvolatile spintronic devices with large areal densities (down to 5-nm pitch sizes or even lower). Existing applications subject spintronic devices to a wide range of operating temperatures (e.g., −55 to 150 °C). To better address the technological viability of FePd for spintronic applications, it is of utmost importance to evaluate the material performance of L10-FePd (e.g., anisotropy strength and Gilbert damping) at elevated temperatures. In this work, we systematically investigate the effect of buffer layers (Cr/Pt, Cr/Ru, Cr/Rh, Cr/Ir, and Ir) on the PMA and Gilbert damping of L10-FePd from room temperature (RT, 25 °C) to 150 °C using the time-resolved magneto-optical Kerr effect metrology. It is found that the effective anisotropy field (Hk,eff) of FePd decreases with the testing temperature (Ttest) and the ratio of Hk,eff(150 °C)/Hk,eff(25 °C) is positively correlated to the degree of L10 phase ordering. The Gilbert damping of L10-FePd either increases with Ttest or stays nearly constant over the Ttest range. We attribute the temperature dependence of Gilbert damping to the spin diffusion length of the metallic buffer layer (λ), presumably through the spin pumping effect. Results of this work provide guidance to tailor L10-FePd properties through buffer layer engineering for applications in spintronic devices over wide operating temperature ranges.

关键词： Magnetic anisotropy Magnetism Magnetization dynamics Spin pumping Spintronics

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