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International Symposium on Physical & Failure Analysis of Integrated Circuits

作者： Erh-Jye Wei Bing-Yue Tsui Pin-Jiun Wu Graduate Program for Science and Technology of Accelerator Light Source National Chiao Tung University Hsinchu Taiwan R.O.C. Department of Electronics Engineering and Institute of Electronics National Chiao Tung University Hsinchu Taiwan R.O.C. National Synchrotron Radiation Research Center (NSRRC) Hsinchu Taiwan R.O.C.

ISBN: (纸本)9781467382601

Germanium metal-insulator-semiconductor (MIS) structure with HfO 2 /Al 2 O 3 /GeO 2 gate stack have been demonstrated to exhibit good performance. In this work, the effect of formation temperature of the gate stack on the quality of the gate dielectric is investigated. It is found that the higher plasma oxidation temperature helps the GeO 2 formation and less interface states. But the higher deposition temperature of the ALD high-k films may degrade the interface and result in higher leakage current.

关键词： Failure analysis Integrated circuits Decision support systems

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Dirac line-nodes and effect of spin-orbit coupling in nonsymmorphic critical semimetal MSiS (M=Hf, Zr)

arXiv

引用

arXiv 2017年

作者： Chen, C. Xu, X. Jiang, J. Wu, S.-C. Qi, Y.P. Yang, L.X. Wang, M.X. Sun, Y. Schröter, N.B.M. Yang, H.F. Schoop, L.M. Lv, Y.Y. Zhou, J. Chen, Y.B. Yao, S.H. Lu, M.H. Chen, Y.F. Felser, C. Yan, B.H. Liu, Z.K. Chen, Y.L. Department of Physics University of Oxford OxfordOX1 3PU United Kingdom State Key Laboratory of Low Dimensional Quantum Physics Department of Physics Tsinghua University Beijing100084 China School of Physical Science and Technology ShanghaiTech University CAS-Shanghai Science Research Center Shanghai China Advanced Light Source Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Accelerator Laboratory POSTECH Pohang790-784 Korea Republic of Max Planck Institute for Chemical Physics of Solids DresdenD-01187 Germany State Key Laboratory of Functional Materials for Informatics SIMIT Chinese Academy of Sciences Shanghai200050 China Max Planck Institute for Solid State Research Stuttgart70569 Germany National Laboratory of Solid State Microstructures School of Physics Department of Materials Science and Engineering Nanjing University NanjingJiangsu210093 China

Topological Dirac semimetals (TDSs) represent a new state of quantum matter recently discovered that offers a platform for realizing many exotic physical phenomena. A TDS is characterized by the linear touching of bulk (conduction and valance) bands at discrete points in the momentum space (i.e. 3D Dirac points), such as in Na3Bi and Cd3As2. More recently, new types of Dirac semimetals with robust Dirac line-nodes (with non-trivial topology or near the critical point between topological phase transitions) have been proposed that extends the bulk linear touching from discrete points to 1D lines. In this work, using angle-resolved photoemission spectroscopy (ARPES), we explored the electronic structure of the non-symmorphic crystals MSiS (M=Hf, Zr). Remarkably, by mapping out the band structure in the full 3D Brillouin Zone (BZ), we observed two sets of Dirac line-nodes in parallel with the kz–axis and their dispersions. Interestingly, along directions other than the line-nodes in the 3D BZ, the bulk degeneracy is lifted by spin-orbit coupling (SOC) in both compounds with larger magnitude in HfSiS. Our work not only experimentally confirms a new Dirac line-node semimetal family protected by non-symmorphic symmetry, but also helps understanding and further exploring the exotic properties as well as practical applications of the MSiS family of compounds. Copyright © 2017, The Authors. All rights reserved.

关键词： Electronic structure

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New high-sensitivity searches for neutrons converting into antineutrons and/or sterile neutrons at the European Spallation source

arXiv

引用

arXiv 2020年

作者： Addazi, A. Anderson, K. Ansell, S. Babu, K.S. Barrow, J. Baxter, D.V. Bentley, P.M. Berezhiani, Z. Bevilacqua, R. Biondi, R. Bohm, C. Brooijmans, G. Broussard, L.J. Dev, B. Crawford, C. Dolgov, A.D. Dunne, K. Fierlinger, P. Fitzsimmons, M.R. Fomin, A. Frost, M. Gardiner, S. Gardner, S. Galindo-Uribarri, A. Geltenbort, P. Girmohanta, S. Golubeva, E. Greene, G.L. Greenshaw, T. Gudkov, V. Hall-Wilton, R. Heilbronn, L. Herrero-Garcia, J. Ichikawa, G. Ito, T.M. Iverson, E. Johansson, T. Jönsson, L. Jwa, Y.-J. Kamyshkov, Y. Kanaki, K. Kearns, E. Kerbikov, B. Kitaguchi, M. Kittelmann, T. Klinkby, E. Kobakhidze, A. Koerner, L.W. Kopeliovich, B. Kozela, A. Kudryavtsev, V. Kupsc, A. Lee, Y. Lindroos, M. Makkinje, J. Marquez, J.I. Meirose, B. Miller, T.M. Milstead, D. Mohapatra, R.N. Morishima, T. Muhrer, G. Mumm, H.P. Nagamoto, K. Nesti, F. Nesvizhevsky, V.V. Nilsson, T. Oskarsson, A. Paryev, E. Pattie, R.W. Penttilä, S. Pokotilovski, Y.N. Potashnikova, I. Redding, C. Richard, J.-M. Ries, D. Rinaldi, E. Rossi, N. Ruggles, A. Rybolt, B. Santoro, V. Sarkar, U. Saunders, A. Senjanovic, G. Serebrov, A.P. Shimizu, H.M. Shrock, R. Silverstein, S. Silvermyr, D. Snow, W.M. Takibayev, A. Tkachev, I. Townsend, L. Tureanu, A. Varriano, L. Vainshtein, A. de Vries, J. Woracek, R. Yamagata, Y. Young, A.R. Zanini, L. Zhang, Z. Zimmer, O. Amherst Center for Fundamental Interactions Department of Physics University of Massachusetts AmherstMA United States INFN Laboratori Nazionali del Gran Sasso Assergi AQ67010 Italy Fermi National Accelerator Laboratory BataviaIL60510-5011 United States Department of Physics Indiana University 727 E. Third St. BloomingtonIN47405 United States Indiana University Center for Exploration of Energy & Matter BloomingtonIN47408 United States Indiana University Quantum Science and Engineering Center BloomingtonIN47408 United States Department of Physics Boston University BostonMA02215 United States Center for Theoretical Physics College of Physics Science and Technology Sichuan University Chengdu610065 China Department of Physics University of Chicago ChicagoIL60637 United States Department of Physics University of Maryland College ParkMD20742-4111 United States Department of Physics and Astronomy University of South Carolina ColumbiaSC29208 United States Dipartimento di Scienze Fisiche e Chimiche Università di L’Aquila Coppito AQ67100 Italy National Institute of Standards and Technology GaithersburgMD20899 United States NRC "Kurchatov Institute" - PNPI Gatchina Russia Physics Department Technical University Munich Garching85748 Germany Institut Laue-Langevin Grenoble38042 France Department of Physics University of Helsinki P.O.Box 64 HelsinkiFIN-00014 Finland Institutionen för Fysik Chalmers Tekniska Högskola Sweden Department of Physics University of Houston HoustonTX77204-5008 United States Department of Physics and Astronomy East Tennessee State University Johnson CityTN37614 United States Department of Physics Kennesaw State University KennesawGA30144 United States Physics Department Indian Institute of Technology Kharagpur721302 India Department of Physics and Astronomy University of Tennessee KnoxvilleTN37996 United States Department of Nuclear Engineering University of Tennessee KnoxvilleTN37996 United States H

The violation of Baryon Number, B, is an essential ingredient for the preferential creation of matter over antimatter needed to account for the observed baryon asymmetry in the universe. However, such a process has yet to be experimentally observed. The HIBEAM/NNBAR program is a proposed two-stage experiment at the European Spallation source (ESS) to search for baryon number violation. The program will include high-sensitivity searches for processes that violate baryon number by one or two units: free neutron-antineutron oscillation (n → n¯) via mixing, neutron-antineutron oscillation via regeneration from a sterile neutron state (n → [n', n¯'] → n¯), and neutron disappearance (n → n');the effective ∆B = 0 process of neutron regeneration (n → [n', n¯'] → n) is also possible. The program can be used to discover and characterise mixing in the neutron, antineutron, and sterile neutron sectors. The experiment addresses topical open questions such as the origins of baryogenesis, the nature of dark matter, and is sensitive to scales of new physics substantially in excess of those available at colliders. A goal of the program is to open a discovery window to neutron conversion probabilities (sensitivities) by up to three orders of magnitude compared with previous searches. The opportunity to make such a leap in sensitivity tests should not be squandered. The experiment pulls together a diverse international team of physicists from the particle (collider and low energy) and nuclear physics communities, while also including specialists in neutronics and magnetics. Copyright © 2020, The Authors. All rights reserved.

关键词： Neutrons

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Observation of the topological surface state in the nonsymmorphic topological insulator KHgSb

引用

Physical Review B 2017年第16期96卷 165143-165143页

作者： A. J. Liang J. Jiang M. X. Wang Y. Sun N. Kumar C. Shekhar C. Chen H. Peng C. W. Wang X. Xu H. F. Yang S. T. Cui G. H. Hong Y.-Y. Xia S.-K. Mo Q. Gao X. J. Zhou L. X. Yang C. Felser B. H. Yan Z. K. Liu Y. L. Chen School of Physical Science and Technology ShanghaiTech University Shanghai 201210 People's Republic of China Advanced Light Source Lawrence Berkeley National Laboratory Berkeley California 94720 USA Pohang Accelerator Laboratory POSTECH Pohang 790-784 Korea Max Planck Institute for Chemical Physics of Solids D-01187 Dresden Germany Department of Physics University of Oxford Oxford OX1 3PU United Kingdom State Key Laboratory of Functional Materials for Informatics SIMIT Chinese Academy of Sciences Shanghai 200050 People's Republic of China State Key Laboratory of Low Dimensional Quantum Physics Department of Physics and Collaborative Innovation Center of Quantum Matter Tsinghua University Beijing 100084 People's Republic of China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 People's Republic of China Collaborative Innovation Center of Quantum Matter Beijing 100190 People's Republic of China Department of Condensed Matter Physics Weizmann Institute of Science Rehovot 7610001 Israel Hefei Science Center CAS and SCGY University of Science and Technology of China Hefei 230026 People's Republic of China

Topological insulators represent unusual topological quantum states, typically with gapped bulk band structure but gapless surface Dirac fermions protected by time-reversal symmetry. Recently, a distinct kind of topological insulator resulting from nonsymmorphic crystalline symmetry was proposed in the KHgX (X=As, Sb, Bi) compounds. Unlike regular topological crystalline insulators, the nonsymmorphic glide-reflection symmetry in KHgX guarantees the appearance of an exotic surface fermion with hourglass shape dispersion (where two pairs of branches switch their partners) residing on its (010) side surface, contrasting to the usual two-dimensional Dirac fermion form. Here, by using high-resolution angle-resolved photoemission spectroscopy, we systematically investigate the electronic structures of KHgSb on both (001) and (010) surfaces and reveal the unique in-gap surface states on the (010) surface with delicate dispersion consistent with the “hourglass Fermion” recently proposed. Our experiment strongly supports that KHgSb is a nonsymmorphic topological crystalline insulator with hourglass fermions, which serves as an important step to the discovery of unique topological quantum materials and exotic fermions protected by nonsymmorphic crystalline symmetry.

关键词： Electronic structure Semiconductors Topological materials Angle-resolved photoemission spectroscopy

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Author Correction: Membrane protein megahertz crystallography at the European XFEL

引用

Nature communications 2020年第1期11卷 703页

作者： Chris Gisriel Jesse Coe Romain Letrun Oleksandr M Yefanov Cesar Luna-Chavez Natasha E Stander Stella Lisova Valerio Mariani Manuela Kuhn Steve Aplin Thomas D Grant Katerina Dörner Tokushi Sato Austin Echelmeier Jorvani Cruz Villarreal Mark S Hunter Max O Wiedorn Juraj Knoska Victoria Mazalova Shatabdi Roy-Chowdhury Jay-How Yang Alex Jones Richard Bean Johan Bielecki Yoonhee Kim Grant Mills Britta Weinhausen Jose D Meza Nasser Al-Qudami Saša Bajt Gerrit Brehm Sabine Botha Djelloul Boukhelef Sandor Brockhauser Barry D Bruce Matthew A Coleman Cyril Danilevski Erin Discianno Zachary Dobson Hans Fangohr Jose M Martin-Garcia Yaroslav Gevorkov Steffen Hauf Ahmad Hosseinizadeh Friederike Januschek Gihan K Ketawala Christopher Kupitz Luis Maia Maurizio Manetti Marc Messerschmidt Thomas Michelat Jyotirmoy Mondal Abbas Ourmazd Gianpietro Previtali Iosifina Sarrou Silvan Schön Peter Schwander Megan L Shelby Alessandro Silenzi Jolanta Sztuk-Dambietz Janusz Szuba Monica Turcato Thomas A White Krzysztof Wrona Chen Xu Mohamed H Abdellatif James D Zook John C H Spence Henry N Chapman Anton Barty Richard A Kirian Matthias Frank Alexandra Ros Marius Schmidt Raimund Fromme Adrian P Mancuso Petra Fromme Nadia A Zatsepin Biodesign Center for Applied Structural Discovery Arizona State University Tempe AZ 85287-5001 USA. School of Molecular Sciences Arizona State University Tempe AZ 85287-1604 USA. Department of Chemistry Yale University New Haven CT 06520 USA. European XFEL GmbH Holzkoppel 4 22869 Schenefeld Germany. Center for Free-Electron Laser Science Deutsches Elektronen-Synchrotron Notkestrasse 85 22607 Hamburg Germany. Department of Physics Arizona State University Tempe AZ 85287-1504 USA. Hauptman-Woodward Institute 700 Ellicott St Buffalo NY 14203-1102 USA. Department of Structural Biology Jacobs School of Medicine and Biomedical Sciences SUNY University at Buffalo 700 Ellicott St Buffalo NY 14203-1102 USA. Linac Coherent Light Source SLAC National Accelerator Laboratory Menlo Park 94025 CA USA. Department of Physics Universität Hamburg Luruper Chaussee 149 22761 Hamburg Germany. The Hamburg Centre for Ultrafast Imaging Universität Hamburg Luruper Chaussee 149 22761 Hamburg Germany. Deutsches Elektronen-Synchrotron Notkestrasse 85 22607 Hamburg Germany. Institute for X-Ray Physics University of Göttingen 37077 Göttingen Germany. Center Nanoscale Microscopy and Molecular Physiology of the Brain Göttingen Germany. Biological Research Centre Hungarian Academy of Sciences Temesvári krt. 62 Szeged 6726 Hungary. Department of Biochemistry & Cellular and Molecular Biology University of Tennessee at Knoxville Knoxville TN USA 37996. Program in Energy Science and Engineering University of Tennessee at Knoxville Knoxville TN USA 37996. Department of Microbiology University of Tennessee at Knoxville Knoxville TN USA 37996. Lawrence Livermore National Laboratory 7000 East Avenue Livermore CA 94550 USA. University of Southampton University Rd Southampton SO17 1BJ UK. Hamburg University of Technology Vision Systems E-2 Harburger Schloßstraße 20 21079 Hamburg Germany. Department of Physics University of Wisconsin-Milwaukee 3135 N. Maryla

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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Photoemission study of the electronic structure of valence band convergent SnSe

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Physical Review B 2017年第16期96卷 165118-165118页

作者： C. W. Wang Y. Y. Y. Xia Z. Tian J. Jiang B. H. Li S. T. Cui H. F. Yang A. J. Liang X. Y. Zhan G. H. Hong S. Liu C. Chen M. X. Wang L. X. Yang Z. Liu Q. X. Mi G. Li J. M. Xue Z. K. Liu Y. L. Chen Center for Excellence in Superconducting Electronics State Key Laboratory of Functional Material for Informatics Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China School of Physical Science and Technology ShanghaiTech University CAS-Shanghai Science Research Center Shanghai 200031 China University of Chinese Academy of Sciences Beijing 100049 China Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China Advanced Light Source Lawrence Berkeley National Laboratory Berkeley California 94720 USA Pohang Accelerator Laboratory POSTECH Pohang 790-784 Korea Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai 200050 China Department of Physics University of Oxford Oxford OX1 3PU United Kingdom Collaborative Innovation Center of Quantum Matter Beijing China State Key Laboratory of Low Dimensional Quantum Physics Department of Physics and Collaborative Innovation Center of Quantum Matter Tsinghua University Beijing 100084 China

IV-VI semiconductor SnSe has been known as the material with record high thermoelectric performance. The multiple close-to-degenerate (or “convergent”) valence bands in the electronic band structure has been one of the key factors contributing to the high power factor and thus figure of merit in the SnSe single crystal. To date, there have been primarily theoretical calculations of this particular electronic band structure. In this paper, however, using angle-resolved photoemission spectroscopy, we perform a systematic investigation of the electronic structure of SnSe. We directly observe three predicted hole bands with small energy differences between their band tops and relatively small in-plane effective masses, in good agreement with the ab initio calculations and critical for the enhancement of the Seebeck coefficient while keeping high electrical conductivity. Our results reveal the complete band structure of SnSe and help to provide a deeper understanding of the electronic origin of the excellent thermoelectric performances in SnSe.

关键词： Electronic structure Seebeck effect Angle-resolved photoemission spectroscopy Density functional theory Hybrid functionals

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Probing molecular photoinduced dynamics by ultrafast soft x-rays

Probing molecular photoinduced dynamics by ultrafast soft x-...

引用

Conference on Lasers and Electro-Optics Europe (CLEO EUROPE)

作者： T. J. A. Wolf R. H. Myhre J. P. Cryan S. Coriani R. J. Squibb A. Battistoni N. Berrah C. Bostedt P. Bucksbaum G. Coslovich R. Feifel K. J. Gaffney J. Grilj T. J. Martinez S. Miyabe S. P. Moeller M. Mucke A. Natan R. Obaid T. Osipov O. Plekan S. Wang H. Koch M. Gühr Stanford PULSE Institute SLAC National Accelerator Laboratory Menlo Park CA USA Department of Chemistry Norwegian University of Science and Technology Trondheim Norway Aarhus Institute of Advanced Studies Aarhus University Aarhus C Denmark Dipartimento di Scienze Chimiche e Farmaceutiche Università degli Studi di Trieste Italy Department of Physics University of Gothenburg Gothenburg Sweden Department of Physics University of Connecticut Connecticut USA Department of Physics and Astronomy Northwestern University Evanston Illinois USA Linac Coherent Light Source SLAC National Accelerator Laboratory Menlo Park California USA Argonne National Laboratory Illinois USA Department of Physics Stanford University Stanford CA USA Laboratory of Ultrafast Spectroscopy Ecole Polytechnique Federal de Lausanne Switzerland Department of Chemistry Stanford University Stanford California USA Laser Technology Laboratory RIKEN Wako Saitama Japan Department of Physics and Astronomy Uppsala University Uppsala Sweden Elettra-Sincrotrone Trieste Trieste Italy Institut für Physik und Astronomie Universität Potsdam Potsdam Germany

ISBN: (纸本)9781509067374

Summary form only given. Molecules selectively transform light energy from the sun into other forms of energy like heat, electricity, or chemical energy with high quantum efficiency. The energy conversion process is the result of a correlated motion of electrons and nuclei after photoexcitation, often under breakdown of the Born-Oppenheimer approximation. The element and site selectivity of x-rays allows observing molecular processes from a different point of view compared to ultrafast optical probes [1,2]. I will concentrate on time resolved x-ray absorption spectroscopy. The method provides high selectivity on the transient electronic structure of a molecule. Recently, we establishes this method in the soft x-ray domain for probing ππ* to nπ* transitions, a general and important process for molecular energy conversion. Fig. 1 shows a sketch of thymine, used in the experiment, with one of the oxygen 1s core orbitals and the π,n and π* valence orbitals. While valence orbitals are generally delocalized over the whole molecular body, the lone pair n orbital is essentially an oxygen 2p orbital. An x-ray induced transition from the oxygen 1s to the n orbital will result in a strong absorption maximum in the pre-edge region. We use this feature to probe the molecular dynamics after photoexcitation.

关键词： X-rays Absorption Physics Probes Transient analysis Chemistry Astronomy

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Distinct Electronic Structure for the Extreme Magnetoresistance in YSb

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Physical Review Letters 2016年第26期117卷 267201-267201页

作者： Junfeng He Chaofan Zhang Nirmal J. Ghimire Tian Liang Chunjing Jia Juan Jiang Shujie Tang Sudi Chen Yu He S.-K. Mo C. C. Hwang M. Hashimoto D. H. Lu B. Moritz T. P. Devereaux Y. L. Chen J. F. Mitchell Z.-X. Shen Stanford Institute for Materials and Energy Sciences SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo Park California 94025 USA Geballe Laboratory for Advanced Materials Departments of Physics and Applied Physics Stanford University Stanford California 94305 USA Materials Science Division Argonne National Laboratory Argonne Illinois 60439 USA Advanced Light Source Lawrence Berkeley National Laboratory Berkeley California 94720 USA School of Physical Science and Technology ShanghaiTech University Shanghai 200031 People’s Republic of China Pohang Accelerator Laboratory Pohang University of Science and Technology Pohang 790-784 Korea Stanford Synchrotron Radiation Lightsource SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo Park California 94025 USA Physics Department University of Oxford Oxford OX1 3PU United Kingdom

An extreme magnetoresistance (XMR) has recently been observed in several nonmagnetic semimetals. Increasing experimental and theoretical evidence indicates that the XMR can be driven by either topological protection or electron-hole compensation. Here, by investigating the electronic structure of a XMR material, YSb, we present spectroscopic evidence for a special case which lacks topological protection and perfect electron-hole compensation. Further investigations reveal that a cooperative action of a substantial difference between electron and hole mobility and a moderate carrier compensation might contribute to the XMR in YSb.

关键词： Electronic structure Magnetotransport Single crystal materials Angle-resolved photoemission spectroscopy Density functional theory

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Realization of quantum spin hall state in monolayer 1T’-WTe2

arXiv

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arXiv 2017年

作者： Tang, Shujie Zhang, Chaofan Wong, Dillon Pedramrazi, Zahra Tsai, Hsin-Zon Jia, Chunjing Moritz, Brian Claassen, Martin Ryu, Hyejin Kahn, Salman Jiang, Juan Yan, Hao Hashimoto, Makoto Lu, Donghui Moore, Robert G. Hwang, Chancuk Hwang, Choongyu Hussain, Zahid Chen, Yulin Ugeda, Miguel M. Liu, Zhi Xie, Xiaoming Devereaux, Thomas P. Crommie, Michael F. Mo, Sung-Kwan Shen, Zhi-Xun Stanford Institute for Materials and Energy Sciences SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo ParkCA94025 United States Geballe Laboratory for Advanced Materials Departments of Physics and Applied Physics Stanford University StanfordCA94305 United States Advanced Light Source Lawrence Berkeley National Laboratory BerkeleyCA94720 United States State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai200050 China School of Physical Science and Technology Shanghai Tech University Shanghai200031 China Department of Physics University of California at Berkeley BerkeleyCA94720 United States Max Plank POSTECH Center for Complex Phase Materials POSTECH Pohang37673 Korea Republic of Department of Physics Pusan National University Busan46241 Korea Republic of Pohang Accelerator Laboratory POSTECH Pohang37673 Korea Republic of Department of Physics and Clarendon Laboratory University of Oxford Parks Road OxfordOX1 3PU United Kingdom Stanford Synchrotron Radiation Lightsource SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo ParkCA94025 United States Ikerbasque Basque Foundation for Science Bilbao48013 Spain CIC nanoGUNE San Sebastián20018 Spain Materials Sciences Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Kavli Energy Nano Sciences Institute University of California and Lawrence Berkeley National Laboratory BerkeleyCA94720 United States

A quantum spin Hall (QSH) insulator is a novel two-dimensional quantum state of matter that features quantized Hall conductance in the absence of magnetic field, resulting from topologically protected dissipationless edge states that bridge the energy gap opened by band inversion and strong spin-orbit coupling. By investigating electronic structure of epitaxially grown monolayer 1T’-WTe2 using angle-resolved photoemission (ARPES) and first principle calculations, we observe clear signatures of the topological band inversion and the band gap opening, which are the hallmarks of a QSH state. Scanning tunneling microscopy measurements further confirm the correct crystal structure and the existence of a bulk band gap, and provide evidence for a modified electronic structure near the edge that is consistent with the expectations for a QSH insulator. Our results establish monolayer 1T’-WTe2 as a new class of QSH insulator with large band gap in a robust two-dimensional materials family of transition metal dichalcogenides (TMDCs). Copyright © 2017, The Authors. All rights reserved.

关键词： Monolayers

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Correlations in Scattered X-Ray Laser Pulses Reveal Nanoscale Structural Features of Viruses

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Physical Review Letters 2017年第15期119卷 158102-158102页

作者： Ruslan P. Kurta Jeffrey J. Donatelli Chun Hong Yoon Peter Berntsen Johan Bielecki Benedikt J. Daurer Hasan DeMirci Petra Fromme Max Felix Hantke Filipe R. N. C. Maia Anna Munke Carl Nettelblad Kanupriya Pande Hemanth K. N. Reddy Jonas A. Sellberg Raymond G. Sierra Martin Svenda Gijs van der Schot Ivan A. Vartanyants Garth J. Williams P. Lourdu Xavier Andrew Aquila Peter H. Zwart Adrian P. Mancuso European XFEL GmbH Holzkoppel 4 D-22869 Schenefeld Germany Mathematics Department Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley California 94720 USA Center for Advanced Mathematics for Energy Research Applications 1 Cyclotron Road Berkeley California 94720 USA Linac Coherent Light Source SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo Park California 94025 USA Australian Research Council Centre of Excellence in Advanced Molecular Imaging La Trobe Institute for Molecular Science La Trobe University Melbourne 3086 Australia Laboratory of Molecular Biophysics Department of Cell and Molecular Biology Uppsala University SE-751 24 Uppsala Sweden Biosciences Division SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo Park California 94025 USA Stanford PULSE Institute SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo Park California 94025 USA Biodesign Center for Applied Structural Discovery and School of Molecular Sciences Arizona State University Tempe Arizona 85287-1604 USA NERSC Lawrence Berkeley National Laboratory Berkeley California 94720 USA Division of Scientific Computing Science for Life Laboratory Department of Information Technology Uppsala University SE-751 05 Uppsala Sweden Molecular Biophysics and Integrated Bioimaging Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley California 94720 USA Biomedical and X-Ray Physics Department of Applied Physics AlbaNova University Center KTH Royal Institute of Technology Stockholm SE-106 91 Sweden Deutsches Elektronen-Synchrotron DESY Notkestraße 85 D-22607 Hamburg Germany National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) Kashirskoe shosse 31 115409 Moscow Russia NSLS-II Brookhaven National Laboratory P.O. Box 5000 Upton New York 11973 USA Center for Free-Electron Laser Science Deutsches Elektronen-Synchrotron DESY Notkestraße 85 22607 Hamburg Germany Max-Planck Institute for the Structure and Dy

We use extremely bright and ultrashort pulses from an x-ray free-electron laser (XFEL) to measure correlations in x rays scattered from individual bioparticles. This allows us to go beyond the traditional crystallography and single-particle imaging approaches for structure investigations. We employ angular correlations to recover the three-dimensional (3D) structure of nanoscale viruses from x-ray diffraction data measured at the Linac Coherent light source. Correlations provide us with a comprehensive structural fingerprint of a 3D virus, which we use both for model-based and ab initio structure recovery. The analyses reveal a clear indication that the structure of the viruses deviates from the expected perfect icosahedral symmetry. Our results anticipate exciting opportunities for XFEL studies of the structure and dynamics of nanoscale objects by means of angular correlations.

关键词： Biomolecular structure Viruses Coherent X-ray scattering Femtosecond laser irradiation X-ray imaging

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