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Kociak M.,CNRS Laboratory of Solid State Physics | Zagonel L.F.,University of Campinas
Ultramicroscopy | Year: 2016

Cathodoluminescence (CL) is a powerful tool for the investigation of optical properties of materials. In recent years, its combination with scanning transmission electron microscopy (STEM) has demonstrated great success in unveiling new physics in the field of plasmonics and quantum emitters. Most of these results were not imaginable even twenty years ago, due to conceptual and technical limitations. The purpose of this review is to present the recent advances that broke these limitations, and the new possibilities offered by the modern STEM-CL technique. We first introduce the different STEM-CL operating modes and the technical specificities in STEM-CL instrumentation. Two main classes of optical excitations, namely the coherent one (typically plasmons) and the incoherent one (typically light emission from quantum emitters) are investigated with STEM-CL. For these two main classes, we describe both the physics of light production under electron beam irradiation and the physical basis for interpreting STEM-CL experiments. We then compare STEM-CL with its better known sister techniques: scanning electron microscope CL, photoluminescence, and electron energy-loss spectroscopy. We finish by comprehensively reviewing recent STEM-CL applications. © 2016 Elsevier B.V.

Sedlmayr N.,CEA Saclay Nuclear Research Center | Aguiar-Hualde J.M.,CEA Saclay Nuclear Research Center | Bena C.,CEA Saclay Nuclear Research Center | Bena C.,CNRS Laboratory of Solid State Physics
Physical Review B - Condensed Matter and Materials Physics | Year: 2015

In this paper, we show that for a range of configurations of inhomogeneous magnetic fields, it is possible to create flat bands of Majorana states localized on the edges of two-dimensional lattices. Majorana bound states have been predicted to exist in both one-dimensional and two-dimensional systems with Rashba spin-orbit coupling, magnetic fields, and placed in proximity to a superconductor. For the proposed systems, we present the topological phase diagrams, and we study the conditions for weak topology which predict the formation of bands of Majorana states. The Majorana bands are demonstrated to be relatively stable with respect to a variety of different perturbations on both square and hexagonal lattices. ©2015 American Physical Society.

Bazin D.,CNRS Laboratory of Solid State Physics | Bazin D.,University Pierre and Marie Curie | Daudon M.,AP HP
Journal of Physics D: Applied Physics | Year: 2012

Medical treatments and diagnosis now concern concepts, techniques or nanomaterials previously the domain of solid-state physics. Examples of solid-state physics techniques applied to medicine are magnetism, Auger electron spectroscopy, nanometre-scale metallic clusters and synchrotron radiation. Here, we summarize the research into these phenomena to explain the strong interaction between solid-state physics and medicine, with its current tremendous development. © 2012 IOP Publishing Ltd.

Schuler F.,University of Stuttgart | Schamel D.,University of Stuttgart | Salonen A.,CNRS Laboratory of Solid State Physics | Drenckhan W.,CNRS Laboratory of Solid State Physics | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2012

An ideal template for the production of macroporous polystyrene can be prepared from foamed oil-in-water emulsions containing styrene, water, glycerol, and sodium dodecylsulfate. After addition of a photoinitiator the mixture is polymerized with UV light and the foam structure of the precursor is transferred to the polymer. The resulting materials display densely packed cells with windows between adjacent pores (see SEM image; scale bar: 250 μm). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wang K.,CNRS Laboratory of Solid State Physics
Journal of the Optical Society of America B: Optical Physics | Year: 2014

We study the low frequency photonic band structures in square Mediterranean and hexagonal snowflake metallic structures, both constructed upon two sets of adjustable tiles. The band formation and evolution are comparatively investigated with respect to local resonances and their variations following the modulations of the tile sizes and shapes. We show that the lowest frequency bands are formed by s-like resonance modes sustained by the structure tiles, of which the contributions vary following local structure modulations, and, under certain conditions, the second bands (above the first photonic bandgaps) are formed by p-like modes sustained by the same tiles. The s and p bands can both be described in the framework of a tight-binding model, allowing band structure analyses in terms of relations between local resonance modes and their mutual correlations. In this schema, the plasma gaps and the first photonic bandgaps arise naturally from local structure patterns, which determine both the local resonance conditions and their correlation relations. © 2014 Optical Society of America.

Wang K.,CNRS Laboratory of Solid State Physics
Optical and Quantum Electronics | Year: 2015

Low-frequency photonic band structures in two-dimensional metallic lattices are investigated through both numerical and tight-binding approaches. The metallic structures, displaying respectively four and six fold rotational symmetries, are constructed upon different sets of adjustable structure units, allowing probing the contribution of different structure configurations to the band formation. We show that the low-frequency band structures can be described in the tight-binding framework, and analyzed in terms of local resonance modes and their mutual correlations. © 2014, Springer Science+Business Media New York.

Wang K.,CNRS Laboratory of Solid State Physics
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We investigate the light wave states in the octagonal and decagonal quasiperiodic metallic structures by considering their respective approximants at different orders. The mechanisms underlying the light wave behaviors are studied in relation to various structure parameters and configurations. We show that the formation of the first passbands, that delimit the photonic band gaps and determine the plasma gaps, involves only the lowest frequency resonance modes inside the fat tiles, and that light localization occurs due to resonances in high symmetry local centers as well as in the fragments of such centers, formed by the skinny tiles. The structure filling rate affects the localized state frequencies relative to the first passbands, as well as the plasma frequency levels, by modulating the frequency levels of the resonance modes and the widths of the passbands. The results of this study can be generalized to other metallic quasiperiodic and related structures. © 2012 American Physical Society.

Vieyres A.,French National Center for Scientific Research | Perez-Aparicio R.,French National Center for Scientific Research | Albouy P.-A.,CNRS Laboratory of Solid State Physics | Sanseau O.,French National Center for Scientific Research | And 3 more authors.
Macromolecules | Year: 2013

We present a combination of independent techniques in order to characterize vulcanized natural rubber elastomer networks. We combine solid state proton multiple-quantum NMR, equilibrium swelling, mechanical experiments, and in-situ tensile X-ray scattering measurements, all of them giving access to the segmental orientation effects in relation to the cross-linking of the systems. By means of the combination of these techniques, we investigate a set of unfilled natural rubber networks with different levels of cross-linking. The relevance of this work is the application of this approach in order to study the reinforcement effect in filled elastomers with nanoparticles in a following work. © 2013 American Chemical Society.

Cavalier M.,French National Center for Scientific Research | Walls M.,CNRS Laboratory of Solid State Physics | Lisiecki I.,French National Center for Scientific Research | Pileni M.-P.,French National Center for Scientific Research
Langmuir | Year: 2011

We report a solution-phase annealing of spherical Co nanocrystals synthesized in reverse micelles and coated with dodecanoic acid. The deposition of a drop of solution on a transmission electron microscope grid shows that a progressive increase in the temperature to 316 °C results in the progressive crystallographic transition from a polycrystalline and probably face-centered cubic Co phase to the single-crystalline hexagonal close-packed (hcp) Co phase. These nanocrystals are highly stable against oxidation and coalescence. We stress that, to our knowledge, this constitutes the first example in the literature of pure hcp-Co spherical single crystals dispersed in solution. These nanocrystals can be freely manipulated and, due to their low size dispersion, can self-organize on various substrates. © 2011 American Chemical Society.

Yang Z.,French National Center for Scientific Research | Cavalier M.,French National Center for Scientific Research | Walls M.,CNRS Laboratory of Solid State Physics | Bonville P.,CEA Saclay Nuclear Research Center | And 2 more authors.
Journal of Physical Chemistry C | Year: 2012

Here, we report a phase-solution annealing-induced structural transition of 7 nm-Co nanocrystals from the fcc polycrystalline phase to the hcp single-crystalline phase. For any annealing temperature, contrary to what was down in our previous paper (Langmuir 2011, 27, 5014), the same solvent (octyl ether) is used preventing any change in adsorbates related to various solvents on the nanocrystal surface. A careful transmission electron microscopy study, combined with the electron diffraction, confirms the nanocrystal recrystallization mechanism. The annealing process results in neither coalescence nor oxidation. The converted nanocrystals can be easily manipulated and due to their low size dispersion self-organize on an amorphous-carbon-coated grid. Magnetic property investigations, keeping the same nanocrystal environment, show that the structural transition is accompanied by a significant increase in both the blocking temperature (to a near room-temperature value) and the coercivity. © 2012 American Chemical Society.

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