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Molybdenum Disulfide: Scalable Fabrication of Molybdenum Disulfide Nanostructures and their Assembly (Adv. Mater. 43/2020)

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Advanced materials 2020年第43期32卷

作者： Yun Huang Kang Yu Huaizhi Li Kai Xu Zexi Liang Debora Walker Paulo Ferreira Peer Fischer Donglei (Emma) Fan Materials Science and Engineering Program Texas Materials Institute The University of Texas at Austin Austin TX 78712 USA The Department of Advanced Electron Microscopy Imaging and Spectroscopy International Iberian Nanotechnology Laboratory Braga 4715‐330 Portugal Electrical and Computer Engineering University of Illinois at Urbana‐Champaign Urbana IL 61801 USA School of Engineering and Applied Sciences Harvard University Cambridge MA 02138 USA Mechanical Engineering Department and IDMEC Instituto Superior Técnico University of Lisbon Av. Rovisco Pais Lisboa 1049‐001 Portugal Max‐Planck‐Institute for Intelligent Systems Heisenbergstr. 3 Stuttgart 70569 Germany Institute of Physical Chemistry University of Stuttgart Pfaffenwaldring 55 Stuttgart 70569 Germany Walker Department of Mechanical Engineering The University of Texas at Austin Austin TX 78712 USA

Artificial intelligence assisted condition assessment

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Artificial intelligence assisted condition assessment

Corrosion and Prevention 2017

作者： Nash, W. Holloway, L. Drummond, T. Birbilis, N. Department of Materials Science and Engineering Monash University Clayton Australia MEnD Consulting Pty Ltd. West Perth Australia Department of Electrical and Computer Systems Engineering Monash University Clayton Australia

The confluence of aging infrastructure and commodity prices has created a scenario where maintenance costs are often prohibitive and inspection has become the primary means of ensuring the integrity of critical infrastructure. This inspection comes at a considerable cost due to the need provide access to equipment that is often elevated and operating, for example, in the oil and gas environment. Deep learning and artificial intelligence (A.I.) computer vision systems are revolutionising many fields, and condition assessment can take advantage of this progress to provide expert opinion systems on site, and direct inspection resources to areas of high risk. In this work, the capability of semi-supervised deep learning networks to conduct rapid condition assessment of complex steel structures is presented. Currently this technology is applied in post-processing of site photos, although this provides for some time saving, a roadmap is provided to deploying this software for on-site assessment in real time, for example with cameras mounted on drones, or augmented reality headsets, and explore the challenges remaining for field deployment. Some pitfalls of artificial intelligence systems and how to avoid them are discussed, whilst a discussion of the extensibility of these systems is also be presented to illustrate how A.I. can be used to tackle problems in other areas. © Corrosion and Prevention 2017. All rights reserved.

关键词： Inspection

Topologically Protected Helical States in Minimally Twisted Bilayer Graphene

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Physical Review Letters 2018年第3期121卷 037702-037702页

作者： Shengqiang Huang Kyounghwan Kim Dmitry K. Efimkin Timothy Lovorn Takashi Taniguchi Kenji Watanabe Allan H. MacDonald Emanuel Tutuc Brian J. LeRoy Physics Department University of Arizona Tucson Arizona 85721 USA Microelectronics Research Center Department of Electrical and Computer Engineering The University of Texas at Austin Austin Texas 78758 USA Department of Physics The University of Texas at Austin Austin Texas 78712 USA National Institute for Materials Science 1-1 Namiki Tsukuba Ibaraki 305-0044 Japan

In minimally twisted bilayer graphene, a moiré pattern consisting of AB and BA stacking regions separated by domain walls forms. These domain walls are predicted to support counterpropogating topologically protected helical (TPH) edge states when the AB and BA regions are gapped. We fabricate designer moiré crystals with wavelengths longer than 50 nm and demonstrate the emergence of TPH states on the domain wall network by scanning tunneling spectroscopy measurements. We observe a double-line profile of the TPH states on the domain walls, only occurring when the AB and BA regions are gapped. Our results demonstrate a practical and flexible method for TPH state network construction.

关键词： Graphene Topological materials Scanning tunneling spectroscopy

Planar Hall effect in antiferromagnetic MnTe thin films

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arXiv 2018年

作者： Yin, Gen Yu, Jie-Xiang Liu, Yizhou Lake, Roger K. Zang, Jiadong Wang, Kang L. Department of Electrical and Computer Engineering University of California – Los Angeles Los AngelesCA90095 United States Department of Physics and Materials Science Program University of New Hampshire DurhamNH03824 United States Institute of Physics Chinese Academy of Sciences Beijing100190 China Department of Electrical and Computer Engineering University of California – Riverside RiversideCA92521 United States Department of Physics and Astronomy University of California – Los Angeles Los AngelesCA90095 United States

We show that the spin-orbit coupling (SOC) in α-MnTe impacts the transport behavior by generating an anisotropic valence-band splitting, resulting in four spin-polarized pockets near Γ. A minimal k·p model is constructed to capture this splitting by group theory analysis, a tight-binding model and ab initio calculations. The model is shown to describe the rotation symmetry of the zero-field planer Hall effect (PHE). The PHE originates from the band anisotropy given by SOC, and is quantitatively estimated to be 25% ∼ 31% for an ideal thin film with a single antiferromagnetic domain. Copyright © 2018, The Authors. All rights reserved.

关键词： Anisotropy

Metasurfaces: Coherent Perfect Diffraction in Metagratings (Adv. Mater. 36/2020)

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Advanced materials 2020年第36期32卷

作者： Ziying Zhang Ming Kang Xueqian Zhang Xi Feng Yuehong Xu Xieyu Chen Huifang Zhang Quan Xu Zhen Tian Weili Zhang Alex Krasnok Jiaguang Han Andrea Alù Center for Terahertz Waves College of Precision Instrument and Optoelectronics Engineering Key Laboratory of Optoelectronics Information and Technology Tianjin University Tianjin 300072 P. R. China Department of Electrical and Computer Engineering The University of Texas at Austin Austin TX 78712 USA School of Electrical and Computer Engineering Oklahoma State University Stillwater OK 74078 USA Photonics Initiative Advanced Science Research Center City University of New York New York NY 10031 USA Physics Program Graduate Center City University of New York New York NY 10016 USA

Graphene/Ni Wire Foam with Multivalent Manganese Oxide Catalysts for Li-O2 Battery Cathode

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Graphene/Ni Wire Foam with Multivalent Manganese Oxide Catal...

MRS Advances

作者： Liu, Chueh Li, Changling Mutlu, Zafer Ozkan, Cengiz S. Ozkan, Mihrimah Materials Science and Engineering Program University of California RiversideCA United States Department of Electrical Engineering University of California RiversideCA United States Department of Mechanical Engineering University of California RiversideCA United States

Herein, commercial Ni foam coated with self-assembled and linearly-aligned Ni wires is utilized as a cost-effective current collector for application in Li-O2 battery. The Ni wires are furthered deposited with graphene layers (g-Ni wire) to improve electrical conductivity. Multivalent Mn oxides consisting of Mn3O4, Mn2O3 and MnCO3 are used as effective oxygen reduction (ORR) and evolution reaction (OER) catalysts deposited on g-Ni wire current collectors. Specific capacities are respective ∼100 and ∼170 mAh g-1 without or with O2 introduction into the cell. The relative facile synthesis process requiring merely solution-based synthesis at ambient pressure, low temperature and short process time renders the Mn oxides/g-Ni wire electrode promising for Li-O2 battery application. © 2017 materials Research Society.

关键词： Oxides

Nonlocal spin transport mediated by a vortex liquid in superconductors

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arXiv 2018年

作者： Kim, Se Kwon Myers, Roberto Tserkovnyak, Yaroslav Department of Physics and Astronomy University of California Los AngelesCA90095 United States Department of Materials Science and Engineering The Ohio State University ColumbusOH43210 United States Department of Electrical and Computer Engineering The Ohio State University ColumbusOH43210 United States

Departing from the conventional view on superconducting vortices as a parasitic source of dissipation for charge transport, we propose to use mobile vortices as topologically-stable information carriers for spin transport. To this end, we start by constructing a phenomenological theory for the interconversion between spin and vorticity, a topological charge carried by vortices, at the interface between a magnetic insulator and a superconductor, by invoking the interfacial spin Hall eαect therein. We then show that a vortex liquid in superconductors can serve as a spin-transport channel between two magnetic insulators by encoding spin information in the vorticity. The vortexmediated nonlocal signal between the two magnetic insulators is shown to decay algebraically as a function of their separation, contrasting with the exponential decay of the quasiparticle-mediated spin transport. We envision that hydrodynamics of topological excitations, such as vortices in superconductors and domain walls in magnets, may serve as a universal framework to discuss long-range transport properties of ordered materials. Copyright © 2018, The Authors. All rights reserved.

关键词： Vortex flow

Binding a hopfion in chiral magnet nanodisk

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arXiv 2018年

作者： Liu, Yizhou Lake, Roger K. Zang, Jiadong Department of Electrical and Computer Engineering University of California RiversideCA92521 United States Department of Physics and Materials Science Program University of New Hampshire DurhamNH03824 United States Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sci-ences Beijing100190 China

Hopfions are three-dimensional (3D) topological textures characterized by the integer Hopf invariant QH. Here, we present the realization of a zero-field, stable hopfion spin texture in a magnetic system consisting of a chiral magnet nanodisk sandwiched by two films with perpendicular magnetic anisotropy. The preimages of the spin texture and numerical calculations of QH show that the hop-fion has QH = 1. Furthermore, another non-trivial state that includes a monopole{antimonopole pair (MAP) is also stabilized in this system. By applying an external magnetic field, hopfion and MAP states with the same polarization can be switched between each other. The topological transition between the hopfion and the MAP state involves a creation (annihilation) of the MAP and twist of the preimages. Our work paves the way to study non-trivial 3D topological spin textures and stimulates more investigations in the field of 3D spintronics. Copyright © 2018, The Authors. All rights reserved.

关键词： Textures

Atomic-resolution visualization and doping effects of complex structures in intercalated bilayer graphene

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arXiv 2019年

作者： Bonacum, Jason P. O'Hara, Andrew Bao, De-Liang Ovchinnikov, Oleg S. Zhang, Yan-Fang Gordeev, Georgy Arora, Sonakshi Reich, Stephanie Idrobo, Juan-Carlos Haglund, Richard F. Pantelides, Sokrates T. Bolotin, Kirill Department of Physics and Astronomy Vanderbilt University NashvilleTN United States Institute of Physics University of Chinese Academy of Sciences Chinese Academy of Sciences Beijing100190 China Institute for Functional Imaging of Materials Oak Ridge National Laboratory Oak RidgeTN United States Freie Universität Berlin Fachbereich Physik Institut für Experimentalphysik Arnimallee 14 Berlin14195 Germany Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak RidgeTN United States Department of Electrical Engineering and Computer Science Vanderbilt University NashvilleTN37235 United States

Molecules intercalating two-dimensional (2D) materials form complex structures that have been mostly characterized by spatially averaged techniques. Here we use aberration-corrected scanning transmission electron microscopy and densityfunctional-theory (DFT) calculations to study the atomic structure of bilayer graphene (BLG) and few-layer graphene (FLG) intercalated with FeCl3. In BLG we discover two distinct intercalated structures that we identify as monolayer-FeCl3 and monolayer-FeCl2. The two structures are separated by atomically sharp boundaries and induce large but different free-carrier densities in the graphene layers, 7.1 × 10-13cm-2and 7.8 × 1013cm-2respectively. In FLG, we observe multiple FeCl3layers stacked in a variety of possible configurations with respect to one another. Finally, we find that the microscope's electron beam can convert the FeCl3monolayer into FeOCl monolayers in a rectangular lattice. These results reveal the need for a combination of atomically-resolved microscopy, spectroscopy, and DFT calculations to identify intercalated structures and study their properties. Copyright © 2019, The Authors. All rights reserved.

关键词： Iron compounds