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Vapor transport growth of MoS2 nucleated on SiO2 patterns and graphene flakes

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Nano Research 2016年第11期9卷 3504-3514页

作者： Toma Stoica Mihai Stoica Martial Duchamp Andreas Tiedemann Siegfried Mantl Detlev Orutzmacher Dan Buca Beata E. Kardynal peter grunberg institute 9 (pgi 9) andJARA-Fundamentals of Future Information Technologies Forschungszentrum Julich Julich 52425 Germany National institute of Materials Physics Magurele Bucharest 077125 Romania institute of Physical Chemistry 'llie Murgulescu' of the Romanian Academy Bucharest 060021 Romania peter grunberg institute 5 (pgi 5) and JARA-Fundamentals of Future Information Technologies Forschungszentrum Julich Julich 52425 Germany

Vapor transport growth of atomically thin MoS2 layers on patterned substrates is investigated, as it is a step towards the self-aligned growth and formation of heterojunctions, which could be useful in future applications. Enhanced formation of MoS2 flakes at the pattern edges is observed on both the substrates examined, namely, patterned thermal SiO2 on Si（100） and graphene flakes on SiO2. The diffusion driven growth leads to the formation of MoS2 monolayers （MLs） with sizes of tens of micrometers around the edges of SiO2 patterns. The growth mode and the optical quality of the MoS2 flakes can be controlled by varying the substrate temperature. Besides the lateral growth, 3R-type pyramids are obtained on prolonging the growth. Lateral MoS2-graphene heterostructures are obtained by using graphene flakes on SiO2 as a substrate.

关键词： MoS2 localized nucleation andgrowth graphene two-dimensional (2D)heterostructures

Ray tracing particle image velocimetry-Challenges in the application to a packed bed

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Particuology 2024年第1期84卷 194-208页

作者： Christin Velten Mirko Ebert Christian Lessig Katharina Zahringer Lehrstuhl für Strömungsmechanik und Strömungstechnik Otto-von-Guericke-Universität Magdeburg39106MagdeburgGermany institut für Simulation und Graphik Otto-von-Guericke-Universität Magdeburg39106MagdeburgGermany

Ray tracing Particle Image Velocimetry(RT-PIV)is an optical technique for high resolution velocity measurements in challenging optical systems,such as transparent packed beds,that uses ray tracing to correct for distortions introduced by transparent geometries in the light *** ray tracing based correction is a post processing step applied to the raw PIV particle images before classical PIV *** this study,RT-PIV is performed in the top layer of a body centred cubic(bcc)sphere packing with gaseous flow,where optical access is obtained by the use of transparent N-BK7 glass balls with a diameter of d=40 ***-PIV introduces new experimental and numerical challenges,for example a limited field of view,illumination difficulties,a very large required depth of field and high sensitivity to geometric parameters used in the ray tracing *** challenges and their implications are the main scope and discussed in the present ***,the validation of the ray tracing reconstruction step is presented and examples for the obtained corrected vector fields in a packed bed are *** results show the strength of the method in reconstructing velocity fields behind transparent spheres that would not have been accessible by optical measurement techniques without the ray tracing correction.

关键词： Ray tracing particle image velocimetry(RT-PIV) Transparent spherical particles Packed bed Distortion correction Gas flow

A Survey on Sensor-and Communication-Based Issues of Autonomous UAVs

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Computer Modeling in Engineering & Sciences 2024年第2期138卷 1019-1050页

作者： Pavlo Mykytyn Marcin Brzozowski Zoya Dyka peter Langendoerfer IHP-Leibniz-institut für Innovative Mikroelektronik Wireless SystemsFrankfurt(Oder)15236Germany BTU Cottbus-Senftenberg Faculty 1:MINTCottbus03046German

The application field for Unmanned Aerial Vehicle (UAV) technology and its adoption rate have been increasingsteadily in the past years. Decreasing cost of commercial drones has enabled their use at a scale broader thanever before. However, increasing the complexity of UAVs and decreasing the cost, both contribute to a lack ofimplemented securitymeasures and raise new security and safety concerns. For instance, the issue of implausible ortampered UAV sensor measurements is barely addressed in the current research literature and thus, requires moreattention from the research community. The goal of this survey is to extensively review state-of-the-art literatureregarding common sensor- and communication-based vulnerabilities, existing threats, and active or passive cyberattacksagainst UAVs, as well as shed light on the research gaps in the literature. In this work, we describe theUnmanned Aerial System (UAS) architecture to point out the origination sources for security and safety *** the coverage and completeness of each related research work in a comprehensive comparison table as wellas classify the threats, vulnerabilities and cyber-attacks into sensor-based and communication-based ***, for each individual cyber-attack, we describe existing countermeasures or detectionmechanisms andprovide a list of requirements to ensureUAV’s security and *** also address the problem of implausible sensormeasurements and introduce the idea of a plausibility check for sensor data. By doing so, we discover additionalmeasures to improve security and safety and report on a research niche that is not well represented in the currentresearch literature.

关键词： Unmanned aerial vehicle unmanned aerial system cyber security and privacy drone swarm security vulnerabilities cyber-threats cyber-attacks plausibility check

Interdigitated terahertz metamaterial sensors:design with the dielectric perturbation theory

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Photonics Research 2024年第6期12卷 1115-1128页

作者： LEI CAO FANQI MENG ESRAÖZDEMIR YANNIK LOTH MERLE RICHTER ANNA KATHARINA WIGGER MAIRA BEATRIZ PÉREZ SOSA ALAA JABBAR JUMAAH SHIHAB AL-DAFFAIE peter HARING BOLÍVAR HARTMUT G.ROSKOS State Key Laboratory of Advanced Electromagnetic Technology Huazhong University of Science and TechnologyWuhan 430074China Physikalisches institut Johann Wolfgang Goethe-UniversitätFrankfurt am MainGermany University of Siegen Institute for High Frequency and Quantum ElectronicsSiegenGermany Department of Electrical Engineering Eindhoven University of Technology5612 AE EindhovenThe Netherlands

Designing terahertz sensors for highly sensitive detection of nanoscale thin films and a few biomolecules poses a substantial challenge but is crucial for unlocking their full potential in scientific research and advanced *** work presents a strategy for optimizing metamaterial sensors in detecting small quantities of dielectric *** amount of frequency shift depends on intrinsic properties(electric field distribution,Q-factor,and mode volume)of the bare cavity as well as the overlap volume of its high-electric-field zone(s)and the *** by the simplified dielectric perturbation theory,interdigitated electric split-ring resonators(ID-eSRRs)are devised to significantly enhance the detection sensitivity compared with eSRRs without interdigitated ***-eSRR’s fin-gers redistribute the electric field,creating strongly localized enhancements,which boost analyte *** periodic change of the inherent antiphase electric field reduces radiation loss,leading to a higher *** with ID-eSRR sensors operating at around 300 GHz demonstrate a remarkable 33.5 GHz frequency shift upon depositing a 150 nm SiO_(2)layer as an analyte simulant,with a figure of merit improvement of over 50 times compared with structures without interdigitated *** rational design offers a promising avenue for highly sensitive detection of thin films and trace biomolecules.

关键词： dielectric perturbation theory

Optimizing laser coupling,matter heating,and particle acceleration from solids using multiplexed ultraintense lasers

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Matter and Radiation at Extremes 2024年第4期9卷 16-28页

作者： Weipeng Yao Motoaki Nakatsutsumi Sébastien Buffechoux Patrizio Antici Marco Borghesi Andrea Ciardi Sophia N.Chen Emmanuel d’Humières Laurent Gremillet Robert Heathcote Vojtech Horny Paul McKenna Mark N.Quinn Lorenzo Romagnani Ryan Royle Gianluca Sarri Yasuhiko Sentoku Hans-peter Schlenvoigt Toma Toncian Olivier Tresca Laura Vassura Oswald Willi Julien Fuchs LULI-CNRS CEASorbonne UniversitéEcole PolytechniqueInstitut Polytechnique de ParisF-91128 Palaiseau CedexFrance Sorbonne Université Observatoire de ParisUniversité PSLCNRSLERMAF-75005 ParisFrance INRS-EMT 1650 BoulLionel-BouletVarennesQuebec J3X 1S2Canada Center for Plasma Physics School of Mathematics and PhysicsQueen’s University BelfastBelfast BT71NNUnited Kingdom “Horia Hulubei”National institute for Physics and Nuclear Engineering 30 Reactorului StreetRO-077125 Bucharest-MagureleRomania University of Bordeaux Centre Lasers Intenses et ApplicationsCNRSCEAUMR 5107F-33405 TalenceFrance CEA DAMDIFF-91297 ArpajonFrance Université Paris-Saclay CEALMCE91680 Bruyères-le-ChatelFrance Central Laser Facility STFC Rutherford Appleton LaboratoryDidcotUnited Kingdom SUPA Department of PhysicsUniversity of StrathclydeGlasgow G40NGUnited Kingdom Department of Physics University of NevadaRenoNevada 89557USA institute of Laser Engineering Osaka University2-6 YamadaokaSuitaOsaka 565-0871Japan institut fur Laser und Plasmaphysik Heinrich Heine Universitat DusseldorfDusseldorfGermany

Realizing the full potential of ultrahigh-intensity lasers for particle and radiation generation will require multi-beam arrangements due to technology ***,we investigate how to optimize their coupling with solid ***,we show that overlapping two intense lasers in a mirror-like configuration onto a solid with a large preplasma can greatly improve the generation of hot electrons at the target front and ion acceleration at the target *** underlying mechanisms are analyzed through multidimensional particle-in-cell simulations,revealing that the self-induced magnetic fields driven by the two laser beams at the target front are susceptible to reconnection,which is one possible mechanism to boost electron *** addition,the resistive magnetic field generated during the transport of the hot electrons in the target bulk tends to improve their *** simulations also indicate that such effects can be further enhanced by overlapping more than two laser beams.

关键词： laser acceleration particle

Impact of Al addition on the formation of Ni germanosilicide layers under different temperature annealing

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Chinese Physics B 2017年第9期26卷 509-514页

作者：孟骁然平云霞俞文杰薛忠营魏星张苗狄增峰张波赵清太 Shanghai University of Engineering Science Shanghai 201600China State Key Laboratory of Functional Material for Informatics Shanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 200050China peter grunberg institute 9(pgi 9-IT) and JARA-Fundamentals of Future Information TechnologyForschungszentrum JuelichJuelich 52425Germany

Solid reactions between Ni and relaxed Si0.7Ge0.3 substrate were systematically investigated with different Al interlayer thicknesses. The morphology, composition, and micro-structure of the Ni germanosilicide layers were analyzed with different annealing temperatures in the appearance of Al. The germanosilicide layers were characterized by Rutherford backscattering spectrometry, cross-section transmission electron microscopy, scan transmission electron microscopy, and secondary ion mass spectroscopy. It was shown that the incorporation of Al improved the surface and interface morphology of the germanosilicide layers, enhanced the thermal stabilities, and retarded the Ni-rich germanosilicide phase to mono germanosilicide phase. With increasing annealing temperature, Al atoms distributed from the Ni/Si0.7Ge0.3 interface to the total layer of Ni2Si0.7Ge0.3, and finally accumulated at the surface of NiSi0.7Ge0.3. We found that under the assistance of Al atoms, the best quality Ni germanosilicide layer was achieved by annealing at 700？C in the case of 3 nm Al.

关键词： germanosilicide Al Ni

Magnetic skyrmion bundles join the family of topological solitons

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Science China(Physics,Mechanics & Astronomy) 2022年第4期65卷 123-124页

作者： Nikolai S.Kiselev peter Grünberg institut and institute for Advanced Simulation Forschungszentrum JülichJülich D-52425Germany

Magnetic solitons are localized magnetic textures that are similar to ordinary particles-they have defined size and can move and interact with each other. Topological solitons [1],in addition, are characterized by the so-called topological charge or topological index, which allows classifying magnetic solitons and has the following meaning.

关键词： topological solitons ordinary

Electron–plasmon and electron–magnon scattering in ferromagnets from first principles by combining GW and GT self-energies

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npj Computational Materials 2021年第1期7卷 1619-1632页

作者： Dmitrii Nabok Stefan Blügel Christoph Friedrich peter Grünberg institut and institut for Advanced Simulation Forschungszentrum JülichJülich 52425Germany

This work combines two powerful self-energy techniques:the well-known GW method and a self-energy recently developed by us that describes renormalization effects caused by the scattering of electrons with magnons and Stoner *** GT selfenergy,which is fully k-dependent and contains infinitely many spin-flip ladder diagrams,was shown to have a profound impact on the electronic band structure of Fe,Co,and *** the present work,we refine the method by combining GT with the GW *** resulting GWT spectral functions exhibit strong lifetime effects and emergent dispersion *** are in an overall better agreement with experimental spectra than those obtained with GW or GT alone,even showing partial improvements over local-spin-density approximation dynamical mean-field *** performed analysis provides a basis for applying the GWT technique to a wider class of magnetic materials.

关键词： materials theory infinitely

Electric-field driven stability control of skyrmions in an ultrathin transition-metal film

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npj Computational Materials 2022年第1期8卷 992-1000页

作者： Souvik Paul Stefan Heinze peter Grünberg institut and institute for Advanced Simulation Forschungszentrum Jülich and JARA52425JülichGermany institute of Theoretical Physics and Astrophysics Christian-Albrechts-Universität zu KielLeibnizstrasse 1524098KielGermany

To realize future spintronic applications with magnetic skyrmions—topologically nontrivial swirling spin structures—it is essential to achieve efficient writing and deleting capabilities of these ***-field assisted nucleation and annihilation is a promising route,however,the understanding of the underlying microscopic mechanisms is still ***,we show how the stability of individual magnetic skyrmions in an ultrathin transition-metal film can be controlled via external electric *** demonstrate based on density functional theory that it is important to consider the changes of all interactions with electric field,i.e.,the pair-wise exchange,the Dzyaloshinskii–Moriya interaction,the magnetocrystalline anisotropy energy,and the higher-order exchange *** energy barriers for electric-field assisted skyrmion writing and deleting obtained via atomistic spin simulations vary by up to a factor of three more than the variations of the interactions calculated from *** surprising effect originates from the electric-field dependent size of metastable skyrmions at a fixed magnetic *** large changes in lifetimes allow the possibility of electric-field assisted thermally activated writing and deleting of skyrmions.

关键词： field stability film