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arXiv 2019年

作者： van Baren, Jeremiah Ye, Gaihua Yan, Jia-An Ye, Zhipeng Rezaie, Pouyan Yu, Peng Liu, Zheng He, Rui Lui, Chun Hung Department of Physics and Astronomy University of California RiversideCA92521 United States Department of Electrical and Computer Engineering Texas Tech University LubbockTX79409 United States Department of Physics Astronomy and Geosciences Towson University TowsonMD21252 United States School of Materials Science and Engineering Sun Yat-sen University Guangzhou Guangdong510275 China School of Materials Science and Engineering Nanyang Technological University Singapore637371 Singapore

We have investigated the interlayer shear and breathing phonon modes in MoS2 with pure 3R and 2H stacking order by using polarization-dependent ultralow-frequency Raman spectroscopy. We observe up to three shear branches and four breathing branches in MoS2 with thickness from 2 to 13 layers. The breathing modes show the same Raman activity behavior for both polytypes, but the 2H breathing frequencies are consistently several wavenumbers higher than the 3R breathing frequencies, signifying that 2H MoS2 has slightly stronger interlayer lattice coupling than 3R MoS2. In contrast, the shear-mode Raman spectra are strikingly different for 2H and 3R MoS2. While the strongest shear mode corresponds to the highest-frequency branch in the 2H structure, it corresponds to the lowest-frequency branch in the 3R structure. Such distinct and complementary Raman spectra of the 3R and 2H polytypes allow us to survey a broad range of shear modes in MoS2, from the highest to lowest branch. By combining the linear chain model, group theory, effective bond polarizability model and first-principles calculations, we can account for all the major observations in our experiment. Copyright © 2019, The Authors. All rights reserved.

关键词： Molybdenum compounds

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Image processing based on compound flat optics

arXiv

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arXiv 2019年

作者： Zhou, You Zheng, Hanyu Kravchenko, Ivan I. Valentine, Jason Interdisciplinary Materials Science Program Vanderbilt University NashvilleTN37212 United States Department of Electric Engineering and Computer Science Vanderbilt University NashvilleTN37212 United States Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak RidgeTN37831 United States Department of Mechanical Engineering Vanderbilt University NashvilleTN37212 United States

Image processing has become a critical technology in a variety of science and engineering disciplines. While most image processing is performed digitally, optical analog processing has the advantages of being low-power and high-speed though it requires a large volume. Here, we demonstrate optical analog imaging processing using a flat optic for direct image differentiation allowing one to significantly shrink the required optical system size. We first demonstrate how the image differentiator can be combined with traditional imaging systems such as a commercial optical microscope and camera sensor for edge detection. Second, we demonstrate how the entire analog processing system can be realized as a monolithic compound flat optic by integrating the differentiator with a metalens. The compound nanophotonic system manifests the advantage of thin form factor optics as well as the ability to implement complex transfer functions and could open new opportunities in applications such as biological imaging and machine vision. Copyright © 2019, The Authors. All rights reserved.

关键词： Edge detection

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Neuroprosthetics: Durable and Fatigue-Resistant Soft Peripheral Neuroprosthetics for In Vivo Bidirectional Signaling (Adv. Mater. 20/2021)

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Advanced materials 2021年第20期33卷

作者： Hyunseon Seo Sang Ihn Han Kang-Il Song Duhwan Seong Kyungwoo Lee Sun Hong Kim Taesung Park Ja Hoon Koo Mikyung Shin Hyoung Won Baac Ok Kyu Park Soong Ju Oh Hyung-Seop Han Hojeong Jeon Yu-Chan Kim Dae-Hyeong Kim Taeghwan Hyeon Donghee Son School of Medicine Sungkyunkwan University Suwon 16419 Republic of Korea Center for Biomaterials Biomedical Research Institute Korea Institute of Science and Technology Seoul 02792 Republic of Korea Center for Nanoparticle Research Institute of Basic Science (IBS) Seoul 08826 Republic of Korea School of Chemical and Biological Engineering Seoul National University Seoul 08826 Republic of Korea Medical Device Development Center Daegu-Gyeongbuk Medical Innovation Foundation Daegu 41061 Republic of Korea Department of Electrical and Computer Engineering Sungkyunkwan University Suwon 16419 Republic of Korea Department of Electrical and Computer Engineering Inter-University Semiconductor Research Center Seoul National University Seoul 08826 Republic of Korea Department of Materials Science and Engineering Korea University Seoul 02841 Republic of Korea Interdisciplinary Program for Bioengineering Seoul National University Seoul 08826 Republic of Korea Department of Biomedical Engineering SKKU Institute for Convergence Sungkyunkwan University Suwon 16419 Republic of Korea Center for Neuroscience Imaging Research Institute for Basic Science (IBS) Suwon 16419 Republic of Korea Department of Superintelligence Engineering Sungkyunkwan University Suwon 16419 Republic of Korea

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Current-Induced Domain Wall Motion in a Compensated Ferrimagnet

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Physical Review Letters 2018年第5期121卷 057701-057701页

作者： Saima A. Siddiqui Jiahao Han Joseph T. Finley Caroline A. Ross Luqiao Liu Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Department of Materials Science and Engineering Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA

Owing to the difficulty in detecting and manipulating the magnetic states of antiferromagnetic materials, studying their switching dynamics using electrical methods remains a challenging task. By employing heavy-metal–rare-earth–transition-metal alloy bilayers, we experimentally study current-induced domain wall dynamics in an antiferromagnetically coupled system. We show that the current-induced domain wall mobility reaches a maximum at the angular momentum compensation point. With experiment and modeling, we further reveal the internal structures of domain walls and the underlying mechanisms for their fast motion. We show that the chirality of the ferrimagnetic domain walls remains the same across the compensation points, suggesting that spin orientations of specific sublattices rather than net magnetization determine Dzyaloshinskii-Moriya interaction in heavy-metal–ferrimagnet bilayers. The high current-induced domain wall mobility and the robust domain wall chirality in compensated ferrimagnetic material opens new opportunities for high-speed spintronic devices.

关键词： Domain walls Spintronics Ferrimagnets

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Quantum prediction of ultra-low thermal conductivity in lithium intercalation materials

arXiv

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arXiv 2019年

作者： Feng, Tianli O'Hara, Andrew Pantelides, Sokrates T. Department of Physics and Astronomy Department of Electrical Engineering and Computer Science Vanderbilt University NashvilleTN37235 United States Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak RidgeTN37831 United States

Lithium-intercalated layered transition-metal oxides, LixTMO2, brought about a paradigm change in rechargeable batteries in recent decades and show promise for use in memristors, a type of device for future neural computing and on-chip storage. Thermal transport properties, although being a crucial element in limiting the charging/discharging rate, package density, energy efficiency, and safety of batteries as well as the controllability and energy consumption of memristors, are poorly managed or even understood yet. Here, for the first time, we employ quantum calculations including high-order lattice anharmonicity and find that the thermal conductivity κ of LixTMO2 materials is significantly lower than hitherto believed. More specifically, the theoretical upper limit of K of LiCoO2 is 6 W/m-K, 2-6 times lower than the prior theoretical predictions. Delithiation further reduces K by 40-70% for LiCoO2 and LiNbO2. Grain boundaries, strains, and porosity are yet additional causes of thermal-conductivity reduction, while Li-ion diffusion and electrical transport are found to have only a minor effect on phonon thermal transport. The results elucidate several long-standing issues regarding the thermal transport in lithium-intercalated materials and provide guidance toward designing high-energy-density batteries and controllable memristors. Copyright © 2019, The Authors. All rights reserved.

关键词： Thermal conductivity

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Ultra-sharp nanowire arrays natively permeate, record, and stimulate intracellular activity in neuronal and cardiac networks

arXiv

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arXiv 2021年

作者： Liu, Ren Lee, Jihwan Tchoe, Youngbin Pre, Deborah Bourhis, Andrew M. D'Antonio-Chronowska, Agnieszka Robin, Gaelle Lee, Sang Heon Ro, Yun Goo Vatsyayan, Ritwik Tonsfeldt, Karen J. Hossain, Lorraine A. Phipps, M. Lisa Yoo, Jinkyoung Nogan, John Martinez, Jennifer S. Frazer, Kelly A. Bang, Anne G. Dayeh, Shadi A. Integrated Electronics and Biointerfaces Laboratory Department of Electrical and Computer Engineering University of California San Diego 9500 Gilman Drive San DiegoCA92093 United States Conrad Prebys Center for Chemical Genomics Sanford Burnham Prebys Medical Discovery Institute 10901 North Torrey Pines Road San DiegoCA92037 United States Department of Pediatrics University of California San Diego 9500 Gilman Drive San DiegoCA92093 United States Center for Reproductive Science and Medicine Department of Obstetrics Gynecology and Reproductive Sciences University of California San Diego 9500 Gilman Drive San DiegoCA92093 United States Center for Integrated Nanotechnologies Los Alamos National Laboratory Los AlamosNM87545 United States Center for Integrated Nanotechnologies Sandia National Laboratories AlbuquerqueNM87185 United States Center for Materials Interfaces in Research and Applications Department of Applied Physics and Materials Science Northern Arizona University 624 S. Knoles Dr FlagstaffAZ86011 United States

Intracellular access with high spatiotemporal resolution can enhance our understanding of how neurons or cardiomyocytes regulate and orchestrate network activity, and how this activity can be affected with pharmacology or other interventional modalities. Nanoscale devices often employ electroporation to transiently permeate the cell membrane and record intracellular potentials, which tend to decrease rapidly to extracellular potential amplitudes with time. Here, we report innovative scalable, vertical, ultra-sharp nanowire arrays that are individually addressable to enable long-term, native recordings of intracellular potentials. We report large action potential amplitudes that are indicative of intracellular access from 3D tissue-like networks of neurons and cardiomyocytes across recording days and that do not decrease to extracellular amplitudes for the duration of the recording of several minutes. Our findings are validated with cross-sectional microscopy, pharmacology, and electrical interventions. Our experiments and simulations demonstrate that individual electrical addressability of nanowires is necessary for high-fidelity intracellular electrophysiological recordings. This study advances our understanding of and control over high-quality multi-channel intracellular recordings, and paves the way toward predictive, high-throughput, and low-cost electrophysiological drug screening platforms. Copyright © 2021, The Authors. All rights reserved.

关键词： Electrophysiology

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Unidirectional Magnon-Driven Domain Wall Motion Due to the Interfacial Dzyaloshinskii-Moriya Interaction

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Physical Review Letters 2019年第14期122卷 147202-147202页

作者： Kyoung-Whan Kim Seo-Won Lee Jung-Hwan Moon Gyungchoon Go Aurélien Manchon Hyun-Woo Lee Karin Everschor-Sitte Kyung-Jin Lee Institute of Physics Johannes Gutenberg University Mainz 55099 Mainz Germany Center for Spintronics Korea Institute of Science and Technology Seoul 02792 Korea Department of Materials Science and Engineering Korea University Seoul 02841 Korea King Abdullah University of Science and Technology (KAUST) Physical Science and Engineering Division (PSE) Thuwal 23955-6900 Saudi Arabia King Abdullah University of Science and Technology (KAUST) Computer Electrical and Mathematical Science and Engineering Division (CEMSE) Thuwal 23955-6900 Saudi Arabia Department of Physics Pohang University of Science and Technology Pohang 37673 Korea KU-KIST Graduate School of Converging Science and Technology Korea University Seoul 02841 Korea

We demonstrate a unidirectional motion of a quasiparticle without explicit symmetry breaking along the space-time coordinate of the particle motion. This counterintuitive behavior originates from a combined action of two intrinsic asymmetries in the other two directions. We realize this idea with the magnon-driven motion of a magnetic domain wall in thin films with interfacial asymmetry. Contrary to previous studies, the domain wall moves along the same direction regardless of the magnon-flow direction. Our general symmetry analysis and numerical simulation reveal that the odd order contributions from the interfacial asymmetry is unidirectional, which is dominant over bidirectional contributions in the realistic regime. We develop a simple analytic theory on the unidirectional motion, which provides an insightful description of this counterintuitive phenomenon.

关键词： Domain walls Spin waves

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Hetero-Magnetic Swinging Inductor (HMSI) and Its Application for Power Factor Correction Converters 10

Hetero-Magnetic Swinging Inductor (HMSI) and Its Application...

引用

10th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2018

作者： Lu, Shengchang Mei, Yuhui Ding, Chao Ngo, Khai D.T. Liu, Lanbing Lu, Guo-Quan Bradley Department of Electrical and Computer Engineering Virginia Tech Center for Power Electronics Systems BlacksburgVA24061 United States School of Material Science and Engineering Tianjin University Center of High-Temperature Electronic Packaging Tianjin China Department of Materials Science and Engineering Virginia Tech BlacksburgVA24061 United States

ISBN: (纸本)9781479973118

A variable inductor concept based on a magnetic structure consisting of a composite of magnetic materials is introduced to meet designed inductance function of current. A design of the inductor, termed hetero-magnetic swinging inductor (HMSI), was fabricated using a toroid core with a gap that was filled by a custom-developed low-permeability magnetic powder + polymer material. Having the gap filled with the magnetic material allowed for greater flexibility in L-I design with added benefit of low fringe field. We applied this swinging inductor to a Critical Conduction Mode (CRM) Boost power factor correction (PFC) converter to reduce its switching frequency variation range. First, the required L-I curve of the HMSI needed for narrow range of switching frequency was calculated. Then, the HMSI core structure consisting of two magnetic materials was designed. Circuit simulations showed that for a 110-Vrms input, the converter with the HMSI had a switching frequency variation factor, defined as Deltatext{f}/text{fmin}, six times less than that of the converter using a linear inductor. A prototype of the HMSI was fabricated and tested. The effectiveness of using the HMSI to narrow the range of switching frequency variation was verified in a 150 W CRM PFC converter. © 2018 IEEE.

关键词： Magnetic materials

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CdS Nanocrystallines: Synthesis, Structure and Nonlinear Optical Properties

CdS Nanocrystallines: Synthesis, Structure and Nonlinear Opt...

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International Conference on Modern Problems of Radio engineering, Telecommunications and computer science

作者： Oleksandr Yanchuk Oleg V. Marchuk Galyna Myronchuk Iryna A. Moroz Nazariy Andrushchak Oleksii A. Vyshnevskyi Iwan V. Kityk Andriy V. Kityk Katarzyna Ozga Jaroslaw Jedryka Artur Wojciechowski Anatoliy Andrushchak Department of Inorganic and Physical Chemistry Lesya Ukrainka Eastern European National University Lutsk Ukraine Department of Materials Science Lutsk National Technical University Lutsk Ukraine Department of Computer-Aided Design Systems Lviv Polytechnic National University Lviv Ukraine M. P. Semenenko Institute of Geochemistry Mineralogy and Ore Formation NAS of Ukraine Kyiv Ukraine Faculty of Electrical Engineering Czestochowa University of Technology Czestochowa Poland Department of Telecommunication Lviv Polytechnic National University Lviv Ukraine

ISBN: (数字)9781728155661

ISBN: (纸本)9781728155678

We report the synthesis, structure and nonlinear optical properties of cadmium sulphide (CdS) nanocrystallines (NCs) synthesized electrochemically both with and without detergent ATLAS G3300. Relevant structural and morphological features are explored by X-ray diffraction and scanning electron microscopy (SEM) techniques. The efficiency of the second harmonic generation (SHG) appears to be strongly dependent on the energy density of the incident fundamental laser radiation and NC sizes.

关键词： chalcogenides nanocrystalline CdS SEM XRD SHG Second-harmonic generation Nonlinear optical properties Chalcogenides Nanocrystalline Scanning Electron Microscope X-ray diffraction energy density Laser radiation

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High Performance GaN HEMT and Ge Fin FET Device Realizing by Atomic-layer Defect-free Etching with Chlorine Neutral Beam

High Performance GaN HEMT and Ge Fin FET Device Realizing by...

引用

International Symposium on VLSI Technology, Systems and Applications

作者： Daisuke Ohori Niraj Man Shrestha Yiming Li Jenn-Hwan Tarng Seiji Samukawa Department of Electrical and Computer Engineering National Chiao Tung University Hsinchu Taiwan 2-1-1 Katahira Aoba-ku Institute of Fluid Science Tohoku University Sendai Japan Center for mmWave Smart Radar System and Technologies National Chiao Tung University Hsinchu Taiwan National Institute of Advanced Industrial Science and Technology (AIST) Tsukuba Ibaraki Japan 2-1-1 Katahira Aoba-ku Advanced Institute for Materials Research Tohoku University Sendai Japan

ISBN: (数字)9781728142326

ISBN: (纸本)9781728142333

In the fabrication of semiconductor devices, reactive plasmas are widely used in key processes such as microfabrication, surface modification and film deposition, and there are now demands for processing precision at the atomic layer level, and for deposition accuracy that allows the control of structures at the molecular level. However, in ultra-miniature nanoscale devices that will become the mainstream in the future, the use of plasma processes can cause serious problems such as abnormal etching and breakdown of insulation films by the accumulation of ions or electrons emitted from the plasma as shown in Fig. 1, also the formation of surface defects (dangling bond) of over a few tens nm in depth by exposure to ultraviolet (UV) emissions from the plasma. [1] -[4] In particular, since nano-scale devices have a larger surface area compared with the bulk material, plasma processes can have a large influence on the electrical and optical properties of devices due to process-induced defects caused by ultraviolet exposure, which has not caused a problem in the presented devices of 32 nm. Furthermore, since future nanodevices will require size control of three-dimensional structures at the atomic layer level, it will be absolutely essential to control surface chemical reactions with high precision and selectivity at the atomic layer level. Neutral beam process technology has attracted attention as a way of solving these issues [5], [6], as shown in Fig. 2. The neutral beam suppresses the incidence of charged particles and UV photon radiation onto the substrate, and is able to expose the substrate only to energy controlled neutral beam (neutral beam motion energy can be precisely controlled by ion acceleration energy with the applied electric field before neutralization), resulting in ultra-precise nano-processing that can suppress the formation of defects at the atomic layer level and control surface chemical reactions with high precision.

关键词： Atomic layer deposition Process control Ions Nanoscale devices Etching Substrates Chemicals

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