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1. Total Oxidation of Methane on Oxide and Mixed Oxide Ceria-Containing Catalysts

Author

Ioana Fechete, Thomas Maurer, Jacques C. Védrine, Ioan-Cezar Marcu, Marius Constantin Stoian, Vincent Rogé, Liliana Lazar, University of Bucharest (UniBuc), University of Luxemburg, Romanian Academy [IASI], Romanian Academy of Sciences, Lumière, nanomatériaux et nanotechnologies (L2n), Université de Technologie de Troyes (UTT), Laboratoire de Réactivité de Surface (LRS), Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Systèmes Mécaniques et d'Ingénierie Simultanée (LASMIS), and Université de Technologie de Troyes (UTT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Oxide, Catalytic combustion, 010402 general chemistry, Combustion, lcsh:Chemical technology, 7. Clean energy, 01 natural sciences, Catalysis, Methane, lcsh:Chemistry, chemistry.chemical_compound, oxide catalysts, total oxidation, [CHIM]Chemical Sciences, lcsh:TP1-1185, Physical and Theoretical Chemistry, 010405 organic chemistry, methane, 0104 chemical sciences, cerium, chemistry, Chemical engineering, lcsh:QD1-999, 13. Climate action, Anaerobic oxidation of methane, Mixed oxide, Energy source, environment
Abstract

Methane, discovered in 1766 by Alessandro Volta, is an attractive energy source because of its high heat of combustion per mole of carbon dioxide. However, methane is the most abundant hydrocarbon in the atmosphere and is an important greenhouse gas, with a 21-fold greater relative radiative effectiveness than CO2 on a per-molecule basis. To avoid or limit the formation of pollutants that are dangerous for both human health and the atmospheric environment, the catalytic combustion of methane appears to be one of the most promising alternatives to thermal combustion. Total oxidation of methane, which is environmentally friendly at much lower temperatures, is believed to be an efficient and economically feasible way to eliminate pollutants. This work presents a literature review, a statu quo, on catalytic methane oxidation on transition metal oxide-modified ceria catalysts (MOx/CeO2). Methane was used for this study since it is of great interest as a model compound for understanding the mechanisms of oxidation and catalytic combustion on metal oxides. The objective was to evaluate the conceptual ideas of oxygen vacancy formation through doping to increase the catalytic activity for methane oxidation over CeO2. Oxygen vacancies were created through the formation of solid solutions, and their catalytic activities were compared to the catalytic activity of an undoped CeO2 sample. The reaction conditions, the type of catalysts, the morphology and crystallographic facets exposing the role of oxygen vacancies, the deactivation mechanism, the stability of the catalysts, the reaction mechanism and kinetic characteristics are summarized.

Published
2021
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2. Removing the saturation assumption in Bank-Weiser error estimator analysis in dimension three

Author

Jack Hale, Alexei Lozinski, Franz Chouly, Raphaël Bulle, University of Luxembourg [sponsor], University of Luxemburg, Institut de Mathématiques de Bourgogne [Dijon] (IMB), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université de Bourgogne (UB), University of Luxembourg [Luxembourg], Laboratoire de Mathématiques de Besançon (UMR 6623) (LMB), Université de Bourgogne (UB)-Université de Franche-Comté (UFC), and Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010103 numerical & computational mathematics, Residual, 01 natural sciences, Piecewise linear function, Multidisciplinaire, généralités & autres [C99] [Ingénierie, informatique & technologie], Dimension (vector space), Bank-Weiser estimator, Applied mathematics, finite element methods, saturation assumption, 0101 mathematics, Reliability (statistics), Mathematics, residual estimator, Bank-Weiserestimator, Applied Mathematics, Multidisciplinary, general & others [C99] [Engineering, computing & technology], Novelty, Estimator, Extension (predicate logic), 16. Peace & justice, Finite element method, a posteriori error estimation, 010101 applied mathematics, Mathematics [G03] [Physical, chemical, mathematical & earth Sciences], Mathématiques [G03] [Physique, chimie, mathématiques & sciences de la terre], [MATH.MATH-NA]Mathematics [math]/Numerical Analysis [math.NA]
Abstract

International audience; We provide a new argument proving the reliability of the Bank-Weiser estimator for Lagrange piecewise linear finite elements in both dimension two and three. The extension to dimension three constitutes the main novelty of our study. In addition, we present a numerical comparison of the Bank-Weiser and residual estimators for a three-dimensional test case.

Published
2020
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3. Lattice dynamics and Raman spectrum of BaZrO3 single crystals

Author

Philippe Veber, Danila Amoroso, Mario Maglione, Monica Ciomaga Hatnean, Geetha Balakrishnan, Mael Guennou, Jens Kreisel, Philippe Ghosez, Cong Xin, Constance Toulouse, Physics and Materials Science Research Unit, University of Luxemburg, Materials Research and Technology Department, Luxembourg Institute of Science and Technology (LIST), Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Theoretical Materials Physics, Quantum Materials Center (Q-MAT), Université de Liège, CNR SPIN, Luminescence (LUMINESCENCE), Institut Lumière Matière [Villeurbanne] (ILM), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, University of Warwick [Coventry], This work was supported by the Innovative Training Networks (ITN) Marie Sklodowska-Curie Actions-European Joint Doctorate in Functional Material Research (EJD-FunMat) (Project No. 641640). DFT-based calculations have been performed on the NIC4 cluster hosted at the University of Liège, within the ‘Consortium des Équipements de Calcul Intensif’ (CÉCI), funded by F.R.S-FNRS (Grant No. 2.5020.1) and by the Walloon Region. C.T., M.G., J.K. acknowledge financial support from the Fond National de Recherche Luxembourg through a PEARL Grant (No. FNR/P12/4853155/Kreisel). The work at the University of Warwick was supported by the EPSRC, UK (Grant No. EP/M028771/1)., Fonds National de la Recherche - FnR [sponsor], EPSCR [sponsor], and Luxembourg Institute of Science & Technology - LIST [research center]

Subjects
Materials science, Phonon, Physics [G04] [Physical, chemical, mathematical & earth Sciences], FOS: Physical sciences, 02 engineering and technology, Cubic crystal system, 01 natural sciences, symbols.namesake, Condensed Matter::Materials Science, [SPI]Engineering Sciences [physics], Phase (matter), 0103 physical sciences, [CHIM]Chemical Sciences, 010306 general physics, QC, Perovskite (structure), [PHYS]Physics [physics], Condensed Matter - Materials Science, Condensed matter physics, Materials Science (cond-mat.mtrl-sci), Atmospheric temperature range, 021001 nanoscience & nanotechnology, Physique [G04] [Physique, chimie, mathématiques & sciences de la terre], Octahedron, symbols, 0210 nano-technology, Raman spectroscopy, Raman scattering
Abstract

${\mathrm{BaZrO}}_{3}$ is a perovskite that remains in the simple cubic phase at all temperatures, hence with no first-order Raman-active phonon mode allowed by symmetry. Yet, it exhibits an intense Raman spectrum with sharp and well-defined features. Here, we report the evolution of the Raman spectrum of ${\mathrm{BaZrO}}_{3}$ single crystals in a broad temperature range (4--1200 K) and discuss its origin with the support of detailed first-principle calculations of the lattice dynamics. Phonon calculations are performed not only for the cubic phase of ${\mathrm{BaZrO}}_{3}$, but also for the low-symmetry phases with octahedra tilts that have been suspected to exist at the nanoscale. We show that the Raman spectrum shows no direct evidence for these nanodomains, but can instead be explained by classical second-order Raman scattering. We provide an assignment of the dominant features to phonon mode combinations. In particular, we show that the high frequency range of the spectrum is dominated by overtones and shows an image of the phonon density of states corresponding to the stretching modes of the oxygen octahedra.

Published
2019
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4. Photo-induced phase transitions in ferroelectrics

Author

Engin Torun, Charles Paillard, Jorge Íñiguez, Laurent Bellaiche, Ludger Wirtz, Laboratoire Structures, Propriétés et Modélisation des solides (SPMS), Institut de Chimie du CNRS (INC)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Department of Physics Department [Fayetteville], University of Arkansas [Fayetteville], Physics and Materials Science Research Unit, and University of Luxemburg

Subjects
Phase transition, Materials science, Condensed matter physics, Phonon, General Physics and Astronomy, Polarization (waves), 01 natural sciences, Ferroelectricity, chemistry.chemical_compound, Condensed Matter::Materials Science, chemistry, 0103 physical sciences, Barium titanate, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Antiferroelectricity, Lead titanate, 010306 general physics, Ground state
Abstract

International audience; Ferroic materials naturally exhibit a rich number of functionalities, which often arise from thermally , chemically or mechanically induced symmetry breakings or phase transitions. Based on Density Functional Calculations, we demonstrate here that light can drive phase transitions as well in ferroelectric materials such as the perovskite oxides lead titanate and barium titanate. Phonon analysis and total energy calculations reveal that the polarization tends to vanish under illumination , to favor the emergence of non-polar phases, potentially antiferroelectric, and exhibiting a tilt of the oxygen octahedra. Strategies to tailor photo-induced phases based on phonon instabilities in the electronic ground state are also discussed.

Published
2019
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5. Vesicle dynamics in confined steady and harmonically modulated Poiseuille flows

Author

Zakaria Boujja, Hamid Ez-Zahraouy, Christian Wagner, Thomas John, Martin Michael Müller, Chaouqi Misbah, Abdelilah Benyoussef, Universität des Saarlandes [Saarbrücken], Université Mohamed V, Rabat, Laboratoire Interdisciplinaire de Physique [Saint Martin d’Hères] (LIPhy), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Physics and Materials Science Research Unit, University of Luxemburg, Laboratoire de Physique et Chimie Théoriques (LPCT), and Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-BIO-PH]Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], Physics [G04] [Physical, chemical, mathematical & earth Sciences], FOS: Physical sciences, Condensed Matter - Soft Condensed Matter, Parameter space, 01 natural sciences, 010305 fluids & plasmas, Amplitude modulation, Quantitative Biology::Subcellular Processes, 0103 physical sciences, Physics - Biological Physics, 010306 general physics, ComputingMilieux_MISCELLANEOUS, Physics, Physics::Biological Physics, Vesicle, Mechanics, Hagen–Poiseuille equation, Amplitude, Flow (mathematics), Physique [G04] [Physique, chimie, mathématiques & sciences de la terre], Modulation, Biological Physics (physics.bio-ph), Soft Condensed Matter (cond-mat.soft), Center of mass, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft]
Abstract

We present a numerical study of the time-dependent motion of a two-dimensional vesicle in a channel under an imposed flow. In a Poiseuille flow the shape of the vesicle depends on the flow strength, the mechanical properties of the membrane, and the width of the channel as reported in the past. This study is focused on the centered snaking (CSn) shape, where the vesicle shows an oscillatory motion like a swimmer flagella even though the flow is stationary. We quantify this behavior by the amplitude and frequency of the oscillations of the vesicle's center of mass. We observe regions in parameter space, where the CSn coexists with the parachute or the unconfined slipper. The influence of an amplitude modulation of the imposed flow on the dynamics and shape of the snaking vesicle is also investigated. For large modulation amplitudes transitions to static shapes are observed. A smaller modulation amplitude induces a modulation in amplitude and frequency of the center of mass of the snaking vesicle. In a certain parameter range we find that the center of mass oscillates with a constant envelope indicating the presence of at least two stable states., Comment: 10 pages, 7 figures

Published
2019
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6. Control of surface potential at polar domain walls in a nonpolar oxide

Author

Claire Mathieu, Jens Kreisel, D. Martinotti, Ludovic Tortech, Ekhard K. H. Salje, Pierre-Yves Hicher, Mael Guennou, Guillaume F. Nataf, Raphael Haumont, Nick Barrett, Oktay Aktas, Laboratoire d'Etude des NanoStructures et Imagerie de Surface (LENSIS), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Luxembourg Institute of Science and Technology (LIST), Physics and Materials Science Research Unit, University of Luxemburg, Laboratoire de Physico-Chimie de l'Etat Solide (CHIMSOL), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Department of Earth Sciences [University of Cambridge], University of Cambridge [UK] (CAM), Laboratoire Innovation en Chimie des Surfaces et NanoSciences (LICSEN UMR 3685), Nanosciences et Innovation pour les Matériaux, la Biomédecine et l'Energie (ex SIS2M) (NIMBE UMR 3685), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut Parisien de Chimie Moléculaire (IPCM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Electronique et nanoPhotonique Organique (LEPO), Nataf, Guillaume [0000-0001-9215-4717], Salje, Ekhard [0000-0002-8781-6154], Apollo - University of Cambridge Repository, Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Department of Earth Sciences, University of Cambridge, Laboratoire Innovation en Chimie des Surfaces et NanoSciences (LICSEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut Rayonnement Matière de Saclay (IRAMIS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)

Subjects
Materials science, Physics and Astronomy (miscellaneous), FOS: Physical sciences, 02 engineering and technology, 01 natural sciences, Condensed Matter::Materials Science, chemistry.chemical_compound, Electric field, 0103 physical sciences, Microelectronics, General Materials Science, 010306 general physics, [PHYS]Physics [physics], Condensed Matter - Materials Science, Condensed matter physics, business.industry, Materials Science (cond-mat.mtrl-sci), 021001 nanoscience & nanotechnology, Polarization (waves), Ferroelectricity, Piezoelectricity, cond-mat.mtrl-sci, Calcium titanate, Ferromagnetism, chemistry, Polar, 0210 nano-technology, business
Abstract

Ferroic domain walls could play an important role in microelectronics, given their nanometric size and often distinct functional properties. Until now, devices and device concepts were mostly based on mobile domain walls in ferromagnetic and ferroelectric materials. A less explored path is to make use of polar domain walls in nonpolar ferroelastic materials. Indeed, while the polar character of ferroelastic domain walls has been demonstrated, polarization control has been elusive. Here, we report evidence for the electrostatic signature of the domain-wall polarization in nonpolar calcium titanate (CaTiO3). Macroscopic mechanical resonances excited by an ac electric field are observed as a signature of a piezoelectric response caused by polar walls. On the microscopic scale, the polarization in domain walls modifies the local surface potential of the sample. Through imaging of surface potential variations, we show that the potential at the domain wall can be controlled by electron injection. This could enable devices based on nondestructive information readout of surface potential., Comment: 30 pages, 12 figures

Published
2017
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7. Ultrafast acousto-optic mode conversion in optically birefringent ferroelectrics

Author

Pascal Ruello, Mariusz Lejman, Guillaume F. Nataf, Ingrid C. Infante, Jens Kreisel, Brahim Dkhil, Mathieu Edely, Ievgeniia Chaban, Gwenaelle Vaudel, Mael Guennou, Vitalyi Gusev, Thomas Pezeril, Institut des Molécules et Matériaux du Mans (IMMM), Le Mans Université (UM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Structures, Propriétés et Modélisation des solides (SPMS), Institut de Chimie du CNRS (INC)-CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique de l'état condensé (LPEC), Centre National de la Recherche Scientifique (CNRS)-Le Mans Université (UM), Materials Research and Technology (MRT) Department, Luxembourg Institute of Science and Technology (LIST), Laboratoire d'Etude des NanoStructures et Imagerie de Surface (LENSIS), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire d'Acoustique de l'Université du Mans (LAUM), Institut de recherche en ingénierie moléculaire et matériaux fonctionnels de l'université du Maine (IRIMMFUM), Le Mans Université (UM)-Centre National de la Recherche Scientifique (CNRS), CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Physics and Materials Science Research Unit, University of Luxemburg, Luxembourg Institute of Science and Technology (LIST), and University of Luxembourg [Luxembourg]

Subjects
Ferroelectrics and multiferroics, Materials science, Science, Physics [G04] [Physical, chemical, mathematical & earth Sciences], General Physics and Astronomy, Physics::Optics, 02 engineering and technology, 01 natural sciences, 7. Clean energy, General Biochemistry, Genetics and Molecular Biology, Article, law.invention, [SPI]Engineering Sciences [physics], Optics, Ultrafast photonics, law, 0103 physical sciences, 010306 general physics, [PHYS]Physics [physics], [SPI.ACOU]Engineering Sciences [physics]/Acoustics [physics.class-ph], Multidisciplinary, Birefringence, Photoacoustics, business.industry, General Chemistry, Acoustic wave, 021001 nanoscience & nanotechnology, Laser, Ferroelectricity, CMOS, Physique [G04] [Physique, chimie, mathématiques & sciences de la terre], Femtosecond, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Optoelectronics, Photonics, 0210 nano-technology, business, Ultrashort pulse
Abstract

The ability to generate efficient giga–terahertz coherent acoustic phonons with femtosecond laser makes acousto-optics a promising candidate for ultrafast light processing, which faces electronic device limits intrinsic to complementary metal oxide semiconductor technology. Modern acousto-optic devices, including optical mode conversion process between ordinary and extraordinary light waves (and vice versa), remain limited to the megahertz range. Here, using coherent acoustic waves generated at tens of gigahertz frequency by a femtosecond laser pulse, we reveal the mode conversion process and show its efficiency in ferroelectric materials such as BiFeO3 and LiNbO3. Further to the experimental evidence, we provide a complete theoretical support to this all-optical ultrafast mechanism mediated by acousto-optic interaction. By allowing the manipulation of light polarization with gigahertz coherent acoustic phonons, our results provide a novel route for the development of next-generation photonic-based devices and highlight new capabilities in using ferroelectrics in modern photonics., Electrically driven acousto-optic light modulators are limited to frequencies of a few hundred megahertz and are typically no smaller than a few micrometres. Here, the authors demonstrate gigahertz acousto-optic conversion of light polarization in a region of a few nanometres using pulsed laser stimulation of a ferroelectric.

Published
2016
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8. Low energy electron imaging of domains and domain walls in magnesium-doped lithium niobate

Author

Claire Mathieu, Mael Guennou, Cindy L. Rountree, Guillaume F. Nataf, Patrick Grysan, D. Martinotti, Nicholas Barrett, Jens Kreisel, Laboratoire d'Etude des NanoStructures et Imagerie de Surface (LENSIS), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Materials Research and Technology (MRT) Department, Luxembourg Institute of Science and Technology (LIST), Physics and Materials Science Research Unit, University of Luxemburg, Laboratoire d'Electronique et nanoPhotonique Organique (LEPO), and Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX)

Subjects
[PHYS]Physics [physics], 010302 applied physics, Multidisciplinary, Materials science, Condensed matter physics, Band gap, Doping, Lithium niobate, Physics [G04] [Physical, chemical, mathematical & earth Sciences], 02 engineering and technology, Electron, 021001 nanoscience & nanotechnology, 01 natural sciences, Ferroelectricity, Article, law.invention, chemistry.chemical_compound, Low-energy electron microscopy, Physique [G04] [Physique, chimie, mathématiques & sciences de la terre], chemistry, law, Electric field, 0103 physical sciences, Electron microscope, 0210 nano-technology
Abstract

The understanding of domain structures, specifically domain walls, currently attracts a significant attention in the field of (multi)-ferroic materials. In this article, we analyze contrast formation in full field electron microscopy applied to domains and domain walls in the uniaxial ferroelectric lithium niobate, which presents a large 3.8 eV band gap and for which conductive domain walls have been reported. We show that the transition from Mirror Electron Microscopy (MEM – electrons reflected) to Low Energy Electron Microscopy (LEEM – electrons backscattered) gives rise to a robust contrast between domains with upwards (Pup) and downwards (Pdown) polarization, and provides a measure of the difference in surface potential between the domains. We demonstrate that out-of-focus conditions of imaging produce contrast inversion, due to image distortion induced by charged surfaces, and also carry information on the polarization direction in the domains. Finally, we show that the intensity profile at domain walls provides experimental evidence for a local stray, lateral electric field.

Published
2016
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9. Phonon-limited carrier mobility and resistivity from carbon nanotubes to graphene

Author

Christophe Delerue, Jing Li, Henrique Pereira Coutada Miranda, Ludger Wirtz, Ivan Duchemin, Yann-Michel Niquet, Luigi Genovese, Laboratory of Atomistic Simulation (LSIM ), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Physics and Materials Science Research Unit, University of Luxemburg, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), ANR-13-NANO-0009,NOODLES,Modélisation de nanodispositifs pour des applications à faible consommation(2013), ANR-10-NANO-0011,QUASANOVA,Simulations quantiques et comparaison de nano-dispositifs(2010), Service de Physique des Matériaux et Microstructures (SP2M - UMR 9002), Institut Nanosciences et Cryogénie (INAC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and University of Luxembourg: High Performance Computing - ULHPC [research center]

Subjects
Electrical mobility, Electron mobility, Materials science, Band gap, Physics [G04] [Physical, chemical, mathematical & earth Sciences], FOS: Physical sciences, Transport, Nanotechnology, 02 engineering and technology, Carbon nanotube, Transistors, 01 natural sciences, law.invention, Scattering, Condensed Matter::Materials Science, Electrical resistivity and conductivity, law, 0103 physical sciences, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Graphite, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, 010306 general physics, Arrays, [PHYS]Physics [physics], Condensed matter physics, Condensed Matter - Mesoscale and Nanoscale Physics, Graphene, Raman-Spectroscopy, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Physique [G04] [Physique, chimie, mathématiques & sciences de la terre], [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, Graphene nanoribbons
Abstract

Under which conditions do the electrical transport properties of one-dimensional (1D) carbon nanotubes (CNTs) and 2D graphene become equivalent? We have performed atomistic calculations of the phonon-limited electrical mobility in graphene and in a wide range of CNTs of different types to address this issue. The theoretical study is based on a tight-binding method and a force-constant model from which all possible electron-phonon couplings are computed. The electrical resistivity of graphene is found in very good agreement with experiments performed at high carrier density. A common methodology is applied to study the transition from 1D to 2D by considering CNTs with diameter up to 16 nm. It is found that the mobility in CNTs of increasing diameter converges to the same value, the mobility in graphene. This convergence is much faster at high temperature and high carrier density. For small-diameter CNTs, the mobility strongly depends on chirality, diameter, and existence of a bandgap., 12 pages

Published
2015
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10. Extended Security Arguments for Signature Schemes

Author

David Galindo, Özgür Dagdelen, Pierre-Louis Cayrel, Sidi Mohamed El Yousfi Alaoui, Pascal Véron, Center for Advanced Security Research Darmstadt [Darmstadt] (CASED), Technische Universität Darmstadt (TU Darmstadt), Institut de Mathématiques de Toulon - EA 2134 (IMATH), Université de Toulon (UTLN), Laboratory of Algorithmics, Cryptology and Security, University of Luxemburg-Faculty of Science, Technolgy, Laboratoire Hubert Curien [Saint Etienne] (LHC), Institut d'Optique Graduate School (IOGS)-Université Jean Monnet [Saint-Étienne] (UJM)-Centre National de la Recherche Scientifique (CNRS), Technische Universität Darmstadt - Technical University of Darmstadt (TU Darmstadt), Combination of approaches to the security of infinite states systems (CASSIS), Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Inria Nancy - Grand Est, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Department of Formal Methods (LORIA - FM), Laboratoire Lorrain de Recherche en Informatique et ses Applications (LORIA), Institut National de Recherche en Informatique et en Automatique (Inria)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche en Informatique et en Automatique (Inria)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Lorrain de Recherche en Informatique et ses Applications (LORIA), Institut National de Recherche en Informatique et en Automatique (Inria)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), and Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Inria Nancy - Grand Est

Subjects
Theoretical computer science, Open problem, 0211 other engineering and technologies, Cryptography, 0102 computer and information sciences, 02 engineering and technology, 01 natural sciences, [INFO.INFO-CR]Computer Science [cs]/Cryptography and Security [cs.CR], Code (cryptography), 0202 electrical engineering, electronic engineering, information engineering, Forking lemma, Computer Science::Cryptography and Security, Mathematics, 021110 strategic, defence & security studies, business.industry, Applied Mathematics, Extension (predicate logic), Signature (logic), Computer Science Applications, Identification (information), ACM: E.: Data/E.3: DATA ENCRYPTION, 010201 computation theory & mathematics, 020201 artificial intelligence & image processing, business, Algorithm, Schnorr signature, Multivariate cryptography
Abstract

It is known how to transform certain canonical three-pass identification schemes into signature schemes via the Fiat---Shamir transform. Pointcheval and Stern showed that those schemes are existentially unforgeable in the random-oracle model leveraging the, at that time, novel forking lemma. Recently, a number of 5-pass identification protocols have been proposed. Extending the above technique to capture 5-pass identification schemes would allow to obtain novel unforgeable signature schemes. In this paper, we provide an extension of the forking lemma (and the Fiat---Shamir transform) in order to assess the security of what we call $$n$$n-generic signature schemes. These include signature schemes that are derived from certain $$(2n+1)$$(2n+1)-pass identification schemes. In doing so, we put forward a generic methodology for proving the security of a number of signature schemes derived from $$(2n+1)$$(2n+1)-pass identification schemes for $$n\ge 2$$n?2. As an application of this methodology, we obtain two new code-based existentially-unforgeable signature schemes, along with a security reduction. In particular, we solve an open problem in multivariate cryptography posed by Sakumoto, Shirai and Hiwatari at CRYPTO 2011.

Published
2012
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