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Merging Deep Learning, Chemistry, and Diffraction for High-Throughput Material Structure Prediction

Microscopy and Microanalysis 2019年第S2期25卷 168-169页

作者： Matthew L. Gong Brandon D. Miller Ray R. Unocic Khallid Hattar Bryan Reed Dan Masiel Tolga Tasdizen Jeffery A. Aguiar Idaho National Laboratory Nuclear Materials Department Idaho Falls IdahoUSA. University of Utah Scientific Computing Imaging Institute Department of Electrical and Computer Engineering Salt Lake City UtahUSA. Oak Ridge National Laboratory Center for Nanophase Materials Science Oak Ridge TennesseeUSA. Sandia National Laboratories Center for Integrated Nanotechnologies Albuquerque New MexicoUSA. Integrated Dynamic Electron Solutions Pleasanton CaliforniaUSA.

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Picosecond spin orbit torque switching

arXiv

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arXiv 2019年

作者： Jhuria, Kaushalya Hohlfeld, Julius Pattabi, Akshay Martin, Elodie Córdova, Aldo Ygnacio Arriola Shi, Xinping Conte, Roberto Lo Petit-Watelot, Sebastien Rojas-Sanchez, Juan Carlos Malinowski, Gregory Mangin, Stéphane Lemaître, Aristide Hehn, Michel Bokor, Jeffrey Wilson, Richard B. Gorchon, Jon Université de Lorraine CNRS IJL NancyF-54000 France Department of Electrical Engineering and Computer Sciences University of California BerkeleyCA94720 United States Universidad Nacional de Ingeniería Avenida Túpac Amaru 210 Rímac Lima Peru Department of Mechanical Engineering and Materials Science and Engineering Program University of California RiversideCA92521 United States CNRS Université Paris Sud Université Paris-Saclay Palaiseau91120 France Lawrence Berkeley National Laboratory 1 Cyclotron Road BerkeleyCA94720 United States

Reducing energy dissipation while increasing speed in computation and memory is a long-standing challenge for spintronics research1. In the last 20 years, femtosecond lasers have emerged as a tool to control the magnetization in specific magnetic materials at the picosecond timescale2-4. However, the use of ultrafast optics in integrated circuits and memories would require a major paradigm shift. An ultrafast electrical control of the magnetization is far preferable for integrated systems. Here we demonstrate reliable and deterministic control of the out-of-plane magnetization of a 1 nm-thick Co layer with single 6 ps-wide electrical pulses that induce spin orbit torques on the magnetization. We can monitor the ultrafast magnetization dynamics due to the spin orbit torques on sub-picosecond timescales, thus far accessible only by numerical simulations. Due to the short duration of our pulses, we enter a counter-intuitive regime of switching where heat dissipation assists the reversal. Moreover, we estimate a low energy cost to switch the magnetization, projecting to below 1fJ for a (20 nm)3 cell. These experiments prove that spintronic phenomena can be exploited on picosecond time-scales for full magnetic control and should launch a new regime of ultrafast spin torque studies and applications. Copyright © 2019, The Authors. All rights reserved.

关键词： Magnetization

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Lithium Battery Cathodes: Concurrently Approaching Volumetric and Specific Capacity Limits of Lithium Battery Cathodes via Conformal Pickering Emulsion Graphene Coatings (Adv. Energy Mater. 25/2020)

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Advanced Energy materials 2020年第25期10卷

作者： Kyu‐Young Park Jin‐Myoung Lim Norman S. Luu Julia R. Downing Shay G. Wallace Lindsay E. Chaney Hocheon Yoo Woo Jin Hyun Hyeong‐U Kim Mark C. Hersam Department of Materials Science and Engineering Northwestern University Evanston IL 60208 USA SKKU Advanced Institute of Nanotechnology Sungkyunkwan University (SKKU) Suwon Gyeonggi‐do 16419 Korea Department of Chemistry Northwestern University Evanston IL 60208 USA Department of Electrical and Computer Engineering Northwestern University Evanston IL 60208 USA

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Concentric Micromirror Array for High-Speed Optical Dynamic Focusing

Concentric Micromirror Array for High-Speed Optical Dynamic ...

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IEEE/LEOS International Conference on Optical MEMS

作者： Nathan Tessema Ersumo Cem Yalcin Nicolas Pégard Laura Waller Daniel Lopez Rikky Muller San Francisco Graduate Program in Bioengineering University of California Berkeley - University of California USA Departement of Electrical Engineering & Computer Sciences University of California Berkeley USA Department of Applied Physical Sciences University of North Carolina at Chapel Hill Chapel Hill USA Center for Nanoscale Materials Argonne National Laboratory Argonne USA

Optical dynamic focusing has emerged as a speed, complexity and efficiency bottleneck across various applications, which include scanning multi-photon microscopy in biology, maskless lithography and micromachining in material processing, and wavefront correction. Here, we present a 32-ring 23,852-pixel concentric micromirror array capable of performing dynamic focusing for wavelengths of up to 1040 nm with a response rate of up to 8.75 kHz, 30 V drive and a focusing full-width-half-maximum to range ratio of 4.8%.

关键词： Optimized production technology High-speed optical techniques Micromechanical devices Nanophotonics Micromirrors Focusing

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Dimer rattling mode induced low thermal conductivity in an excellent acoustic conductor

arXiv

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arXiv 2020年

作者： Qi, Ji Dong, Baojuan Zhang, Zhe Zhang, Zhao Chen, Yanna Zhang, Qiang Danilkin, Sergey Chen, Xi Fu, Liangwei Jiang, Xiaoming Chai, Guozhi Hiroi, Satoshi Ohara, Koji Zhang, Zongteng Ren, Weijun Yang, Teng Zhou, Jianshi Osami, Sakata He, Jiaqing Yu, Dehong Li, Bing Zhang, Zhidong Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences 72 Wenhua Road Shenyang110016 China School of Materials Science and Engineering University of Science and Technology of China Shenyang110016 China 1-1-1 Kouto Sayo-Cho Sayo-gun Hyogo679-5148 Japan Spallation Neutron Source Oak Ridge National Laboratory Oak RidgeTN37831 United States Australian Nuclear Science and Technology Organisation Locked Bag 2001 Australia Department of Mechanical Engineering University of Texas at Austin AustinTX78712 United States Department of Electrical and Computer Engineering University of California RiversideCA92521 United States Department of Physics South University of Science and Technology of China Shenzhen518005 China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences FuzhouFujian350002 China Key Lab for Magnetism and Magnetic Materials of the Ministry of Education Lanzhou University Lanzhou730000 China SPring-8 Diffraction and Scattering Division Japan Synchrotron Radiation Research Institute 1-1-1 Kouto Sayo-Cho Sayo-gun Hyogo679-5198 Japan State Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Opto-Electronics Shanxi University Taiyuan030006 China Collaborative Innovation Center of Extreme Optics Shanxi University Taiyuan030006 China

A solid with larger sound speeds exhibits higher lattice thermal conductivity (lat) 1-3. Diamond4 is a prominent instance where its mean sound speed is 14400 m s-1 and lat is 2300 W m-1 K-1. Here, we report an extreme exception that CuP2 has quite large mean sound speeds of 4155 m s-1, comparable to GaAs5,6, but the single crystals show a very low lattice thermal conductivity of about 4 W m-1 K-1 at room temperature, one order of magnitude smaller than GaAs. To understand such a puzzling thermal transport behavior, we have thoroughly investigated the atomic structure and lattice dynamics by combining neutron scattering techniques with first-principles simulations. Cu atoms form dimers sandwiched in between the layered P atomic networks and the dimers vibrate as a rattling mode with frequency around 11 meV. This mode is manifested to be remarkably anharmonic and strongly scatters acoustic phonons to achieve the low lat. Such a dimer rattling behavior in layered structures might offer an unprecedented strategy for suppressing thermal conduction without involving atomic disorder. Copyright © 2020, The Authors. All rights reserved.

关键词： III-V semiconductors

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Random lasing in an Anderson localizing optical fiber

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Light(science & Applications) 2017年第1期6卷 577-584页

作者： Behnam Abaie Esmaeil Mobini Salman Karbasi Thomas Hawkins John Ballato Arash Mafi Department of Physics and Astronomy University of New MexicoAlbuquerqueNM 87131USA Center for High Technology Materials University of New MexicoAlbuquerqueNM 87106USA Department of Electrical and Computer Engineering University of CaliforniaSan DiegoCA 92093USA Center for Optical Materials Science and Engineering Technologies(COMSET)and the Department of Materials Science and Engineering Clemson UniversityClemsonSC 29625USA

A directional random laser mediated by transverse Anderson localization in a disordered glass optical fiber is *** demonstrations of random lasers have found limited applications because of their multi-directionality and chaotic fluctuations in the laser *** random laser presented in this paper operates in the Anderson localization *** disorder induced localized states form isolated local channels that make the output laser beam highly directional and stabilize its *** strong transverse disorder and longitudinal invariance result in isolated lasing modes with negligible interaction with their surroundings,traveling back and forth in a Fabry–Perot cavity formed by the air–fiber *** is shown that if a localized input pump is scanned across the disordered fiber input facet,the output laser signal follows the transverse position of the ***,a uniformly distributed pump across the input facet of the disordered fiber generates a laser signal with very low spatial coherence that can be of practical importance in many optical platforms including image transport with fiber bundles.

关键词： disordered optical fiber random lasing transverse Anderson localization

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Identifying irregularity electricity usage of customer behaviors using logistic regression and linear discriminant analysis 3

Identifying irregularity electricity usage of customer behav...

引用

3rd International Conference on science in Information Technology, ICSITech 2017

作者： Lawi, Armin Wungo, Supriyadi La Manjang, Salama Department of Computer Science Post-graduate Program of Electrical Engineering Dept. Electrical Engineering Universitas Hasanuddin Makassar Indonesia

ISBN: (纸本)9781509058662

This study aims to implement a machine learning technique in identifying the irregularities of customer behavior on the use of prepaid electricity pulses. The methods used are Linear Discriminant Analysis and Logistic Regression. The performance of the classification system will be evaluated using the 10-fold cross-validation technique. Validation results are measured using accuracy, precision and recall values. In this research shows that the use of machine learning technique has a good performance in classification of electrical consumption behavior. Experimental results with the different amount of data testing indicate that Logistic Regression method has high accuracy, precision, and recall value when compared with Linear Discriminant Analysis that is 100%. This is due to Logistic Regression method can predict irregularities accurately because the addition of the amount of data does not affect the performance of the method. © 2017 IEEE.

关键词： Regression analysis

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Transferring orbital angular momentum to an electron beam reveals toroidal and chiral order

arXiv

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arXiv 2020年

作者： Nguyen, Kayla X. Jiang, Yi Cao, Michael C. Purohit, Prafull Yadav, Ajay K. García-Fernández, Pablo Tate, Mark W. Chang, Celesta S. Aguado-Puente, Pablo Íñiguez, Jorge Gomez-Ortiz, Fernando Gruner, Sol M. Junquera, Javier Martin, Lane W. Ramesh, Ramamoorthy Muller, D.A. Department of Chemistry and Chemical Biology Cornell University IthacaNY United States Department of Physics Cornell University IthacaNY United States School of Applied and Engineering Physics Cornell University IthacaNY United States Department of Electrical Engineering and Computer Sciences University of California United States Departamento de Ciencias de la Tierra y Física de la Materia Condensada Universidad de Cantabria Cantabria Campus Internacional Avenida de los Castros s/n Santander39005 Spain Atomistic Simulation Center Queen's University Belfast BelfastBT7 1NN United Kingdom 5 avenue des Hauts-Fourneaux Esch/AlzetteL-4362 Luxembourg Physics and Materials Science Research Unit University of Luxembourg 41 Rue du Brill BelvauxL-4422 Luxembourg Kavli Institute at Cornell for Nanoscale Science IthacaNY United States Cornell University IthacaNY United States Department of Material Science and Engineering University of California Berkeley BerkeleyCA94720 United States Materials Sciences Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Department of Physics University of California BerkeleyCA94270 United States

Orbital angular momentum and torque transfer play central roles in a wide range of magnetic textures and devices including skyrmions and spin-torque electronics(1-4). Analogous topological structures are now also being explored in ferroelectrics, including polarization vortex arrays in ferroelectric/dielectric superlattices(5). Unlike magnetic toroidal order, electric toroidal order does not couple directly to linear external fields. To develop a mechanism that can control switching in polarization vortices, we utilize a high-energy electron beam and show that transverse currents are generated by polar order in the ballistic limit. We find that the presence of an electric toroidal moment in a ferro-rotational phase transfers a measurable torque and orbital angular momentum to the electron beam. Furthermore, we find that the complex polarization patterns, observed in these heterostructures, are microscopically chiral with a non-trivial axial component of the polarization. This chirality opens the door for the coupling of ferroelectric and optical properties. © 2020, CC0.

关键词： Electron beams

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Tackling Disorder in γ-Ga2O3

arXiv

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arXiv 2022年

作者： Ratcliff, Laura E. Oshima, Takayoshi Nippert, Felix Janzen, Benjamin M. Kluth, Elias Goldhahn, Rüdiger Feneberg, Martin Mazzolini, Piero Bierwagen, Oliver Wouters, Charlotte Nofal, Musbah Albrecht, Martin Swallow, Jack E.N. Jones, Leanne A.H. Thakur, Pardeep K. Lee, Tien-Lin Kalha, Curran Schlueter, Christoph Veal, Tim D. Varley, Joel B. Wagner, Markus R. Regoutz, Anna Department of Materials Imperial College London LondonSW7 2AZ United Kingdom Centre for Computational Chemistry School of Chemistry University of Bristol BristolBS8 1TS United Kingdom Department of Electrical and Electronic Engineering Saga University Saga840-8502 Japan Technische Universität Berlin Institute of Solid State Physics Hardenbergstrasse 36 Berlin10623 Germany Institut für Physik Otto-von-Guericke-Universität Magdeburg Universitätsplatz 2 Magdeburg39106 Germany Paul-Drude-Institut fur Festkörperelektronik Leibniz-Institut im Forschungsverbund Berlin e.V. Hausvogteiplatz 5-7 Berlin10117 Germany Department of Mathematical Physical and Computer Sciences University of Parma Viale delle Scienze 7/A Parma43124 Italy Paul-Drude-Institut für Festkörperelektronik Leibniz-Institut im Forschungsverbund Berlin e.V. Hausvogteiplatz 5-7 Berlin10117 Germany Leibniz-Institut fÃŒr Kristallzüchtung Max-Born-Str. 2 Berlin12489 Germany Department of Materials University of Oxford Parks Road OxfordOX1 3PH United Kingdom Stephenson Institute for Renewable Energy Department of Physics University of Liverpool LiverpoolL69 7ZF United Kingdom Diamond Light Source Ltd. Diamond House Harwell Science and Innovation Campus Didcot OX11 0DE United Kingdom Diamond Light Source Ltd. Harwell Science and Innovation Campus Didcot OX11 0DE United Kingdom Department of Chemistry University College London 20 Gordon Street LondonWC1H 0AJ United Kingdom Deutsches Elektronen-Synchrotron DESY Notkestrasse 85 Hamburg22607 Germany Lawrence Livermore National Laboratory LivermoreCA94550 United States

Ga2O3 and its polymorphs are attracting increasing attention. The rich structural space of polymorphic oxide systems such as Ga2O3 offers potential for electronic structure engineering, which is of particular interest for a range of applications, such as power electronics. γ-Ga2O3 presents a particular challenge across synthesis, characterisation, and theory due to its inherent disorder and resulting complex structure - electronic structure relationship. Here, density functional theory is used in combination with a machine learning approach to screen nearly one million potential structures, thereby developing a robust atomistic model of the γ-phase. Theoretical results are compared with surface and bulk sensitive soft and hard X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, spectroscopic ellipsometry, and photoluminescence excitation spectroscopy experiments representative of the occupied and unoccupied states of γ-Ga2O3. The first onset of strong absorption at room temperature is found at 5.1 eV from spectroscopic ellipsometry, which agrees well with the excitation maximum at 5.17 eV obtained by PLE spectroscopy, where the latter shifts to 5.33 eV at 5 K. This work presents a leap forward in the treatment of complex, disordered oxides and is a crucial step towards exploring how their electronic structure can be understood in terms of local coordination and overall structure. Copyright © 2022, The Authors. All rights reserved.

关键词： Density functional theory

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Revealing the Origin of Luminescence Center in 0D Cs4PbBr6 Perovskite

arXiv

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arXiv 2019年

作者： Qin, Zhaojun Dai, Shenyu Hadjiev, Viktor G. Wang, Chong Ouyang, Lingxi Xie, Lixin Ni, Yizhou Wu, Chunzheng Yang, Guang Chen, Shuo Deng, Liangzi Yu, Qingkai Chu, Ching-Wu Feng, Guoying Wang, Zhiming Bao, Jiming Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu Sichuan610054 China Department of Electrical and Computer Engineering University of Houston HoustonTX77204 United States College of Electronics & Information Engineering Sichuan University Chengdu Sichuan610064 China Texas Center for Superconductivity University of Houston HoustonTX77204 United States Department of Mechanical Engineering University of Houston HoustonTX77204 United States School of Materials Science and Engineering Yunnan University KunmingYunnan650091 China Department of Physics University of Houston HoustonTX77204 United States Materials Science & Engineering University of Houston HoustonTX77204 United States Ingram School of Engineering Texas State University San MarcosTX78666 United States Lawrence Berkeley National Laboratory BerkeleyCA94720 United States

Zero dimensional perovskite Cs4PbBr6 has attracted considerable attention recently not only because of its highly efficient green photoluminescence (PL), but also its two highly debated opposing mechanisms of the luminescence: embedded CsPbBr3 nanocrystals versus intrinsic Br vacancy states. After a brief discussion on the root cause of the controversy, we provide sensitive but noninvasive methods that can not only directly correlate luminescence with the underlying structure, but also distinguish point defects from embedded nanostructures. We first synthesized both emissive and non-emissive Cs4PbBr6 crystals, obtained the complete Raman spectrum of Cs4PbBr6 and assigned all Raman bands based on density functional theory simulations. We then used correlated Raman-PL as a passive structure-property method to identify the difference between emissive and non-emissive Cs4PbBr6 crystals and revealed the existence of CsPbBr3 nanocrystals in emissive Cs4PbBr6. We finally employed a diamond anvil cell to probe the response of luminescence centers to hydrostatic pressure. The observations of fast red-shifting, diminishing and eventual disappearance of both green emission and Raman below Cs4PbBr6 phase transition pressure of ~3 GPa is compatible with CsPbBr3 nanocrystal inclusions as green PL emitters and cannot be explained by Br vacancies. The resolution of this long-lasting controversy paves the way for further device applications of low dimensional perovskites, and our comprehensive optical technique integrating structure-property with dynamic pressure response is generic and can be applied to other emerging optical materials to understand the nature of their luminescent centers. Copyright © 2019, The Authors. All rights reserved.

关键词： Perovskite

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