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148 results on '"Stéphan Odile"'

1. New insights into optical property characterization of 2D semiconductor materials through time-correlated photon/electron spectroscopies

Author

Castioni Florian, Auad Yves, Varkentina Nadezda, Freilinger Alissa, Woo Steffi Y., Bonnet Noémie, Blazit Jean-Denis, Li Xiaoyan, Tencé Marcel, Watanabe Kenji, Taniguchi Takashi, Stéphan Odile, Kociak Mathieu, and Tizei Luiz H. G.

Subjects
nano-optic, electron/photon spectroscopy, semiconductor tmd, Microbiology, QR1-502, Physiology, QP1-981, Zoology, QL1-991
Published
2024
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10. Engineering 2D Material Exciton Line Shape with Graphene/h‑BN Encapsulation.

Author

Woo, Steffi Y., Shao, Fuhui, Arora, Ashish, Schneider, Robert, Wu, Nianjheng, Mayne, Andrew J., Ho, Ching-Hwa, Och, Mauro, Mattevi, Cecilia, Reserbat-Plantey, Antoine, Moreno, Álvaro, Sheinfux, Hanan Herzig, Watanabe, Kenji, Taniguchi, Takashi, Michaelis de Vasconcellos, Steffen, Koppens, Frank H. L., Niu, Zhichuan, Stéphan, Odile, Kociak, Mathieu, and García de Abajo, F. Javier

Published
2024
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13. Multiresonant behavior and strong coupling in aluminum optical antennas

Author

Simon, Thomas, Arditi, Gabriel, Li, Xiaoyan, Lamaze, Florian, Proust, Julien, Martin, Jérôme, Kociak, Mathieu, Stéphan, Odile, Gérard, Davy, Lumière, nanomatériaux et nanotechnologies (L2n), Université de Technologie de Troyes (UTT)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des Solides (LPS), and Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics]
Abstract

International audience

Published
2023

14. $\mu$eV electron spectromicroscopy using free-space light

Author

Auad, Yves, Dias, Eduardo J. C., Tencé, Marcel, Blazit, Jean-Denis, Li, Xiaoyan, Zagonel, Luiz Fernando, Stéphan, Odile, Tizei, Luiz H. G., de Abajo, F. Javier García, and Kociak, Mathieu

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Physics - Optics
Abstract

The synergy between free electrons and light has recently been leveraged to reach an impressive degree of simultaneous spatial and spectral resolution, enabling applications in microscopy and quantum optics. However, the required combination of electron optics and light injection into the spectrally narrow modes of arbitrary specimens remains a challenge. Here, we demonstrate microelectronvolt spectral resolution in the nanoscale mapping of photonic modes with quality factors as high as 10$^4$. We rely on mode-matching of a tightly focused laser beam to whispering gallery modes to achieve a 10$^8$-fold increase in light-electron coupling efficiency. By adapting the shape and size of free-space optical beams to address specific physical questions, our approach allows us to interrogate any type of photonic structure with unprecedented spectral and spatial detail

Published
2022

16. Fractal-like multiresonant aluminum optical antennas – the Cayley Tree

Author

Simon, Thomas, Li, Xiaoyan, Martin, Jérôme, Khlopin, Dmitry, Stéphan, Odile, Kociak, Mathieu, Gérard, Davy, Lumière, nanomatériaux et nanotechnologies (L2n), Université de Technologie de Troyes (UTT)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des Solides (LPS), and Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics]
Abstract

International audience

Published
2022

21. Interplay between epitaxial strain and low dimensionality effects in a ferrimagnetic oxide.

Author

Popova, Elena, Deb, Marwan, Bocher, Laura, Gloter, Alexandre, Stéphan, Odile, Warot-Fonrose, Bénédicte, Berini, Bruno, Dumont, Yves, and Keller, Niels

Subjects
THIN films, BISMUTH, GARNET, FARADAY effect, EPITAXY
Abstract

Thin film properties are strongly influenced by strain and low dimensionality effects, especially when the film thickness is about a few unit cells, which corresponds to the thicknesses targeted in most of contemporary studies. In oxides, these effects are responsible for the dramatic modification of the physical properties that sometimes can change the nature of a material. Nevertheless, it is not always possible to distinguish the contribution of the strain to the changes in physical properties from the contribution due to low dimensional effects. In the present study, bismuth iron garnet Bi3Fe5O12 (BIG) is chosen to separate both effects. This material possesses, among other outstanding physical properties, the giant Faraday rotation that allows investigating films with the thickness below a few unit cells. Three series of BIG films of various thicknesses were grown on three isostructural substrates with different lattice parameters: Y3Al5O12(001), Gd3Ga5O12(001), and (GdCa)3(GaMgZr)5O12(001). The structural, magnetic, and magneto-optic properties were studied as a function of film thickness and strain. Furthermore, critical behavior of the BIG films was investigated in the vicinity of the Curie temperature. The obtained results allowed distinguishing between the low dimensional effects and the strain due to the epitaxial growth. While the size reduction is mostly responsible for the decrease of the magnetic characteristics of the films, the strain influences rather the critical thickness below which the material starts to behave as a low dimensional system. [ABSTRACT FROM AUTHOR]

Published
2017
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31. Spectroscopies and Electron Microscopies Unravel the Origin of the First Colour Photographs.

Author

Seauve, Victor, Languille, Marie‐Angélique, Kociak, Mathieu, Belin, Stéphanie, Ablett, James, Andraud, Christine, Stéphan, Odile, Rueff, Jean‐Pascal, Fonda, Emiliano, and Lavédrine, Bertrand

Subjects
ELECTRON spectroscopy, ELECTRON microscopy, COLOR photography, OPTICAL properties, SILVER nanoparticles, ELECTRON energy loss spectroscopy
Abstract

The first colour photographs were created by a process introduced by Edmond Becquerel in 1848. The nature of these photochromatic images colours motivated a debate between scientists during the XIXth century, which is still not settled. We present the results of chemical analysis (EDX, HAXPES and EXAFS) and morphology studies (SEM, STEM) aiming at explaining the optical properties of the photochromatic images (UV‐visible spectroscopy and low loss EELS). We rule out the two hypotheses (pigment and interferences) that have prevailed since 1848, respectively based on variations in the oxidation degree of the compound forming the sensitized layer and periodically spaced photolytic silver planes. A study of the silver nanoparticles dispersions contained in the coloured layers showed specific localizations and sizes distributions of the nanoparticles for each colour. These results allow us to formulate a plasmonic hypothesis on the origin of the photochromatic images colours. [ABSTRACT FROM AUTHOR]

Published
2020
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32. Role of point and line defects on the electronic structure of LaAlO3/SrTiO3 interfaces.

Author

Gloter, Alexandre, Tieri, Giulio, Li, Danfeng, Caputo, Marco, Strocov, Vladimir N., Stéphan, Odile, Triscone, Jean-Marc, and Gariglio, Stefano

Subjects
PHOTOEMISSION, POINT defects, SCANNING transmission electron microscopy, ELECTRONIC structure, INTERFACE structures, ANTISITE defects, ELECTRON energy loss spectroscopy
Abstract

Realization of heterostructures containing multiple two-dimensional electron liquids requires a fine control of the fabrication process. Here, we report a structural and spectroscopy study of LaAlO3/SrTiO3/LaAlO3 trilayers grown on the SrTiO3 substrate by pulsed-laser deposition. Scanning transmission electron microscopy with the help of ab initio calculations reveals that antisite defects associated with oxygen vacancies are primarily present in the SrTiO3 film (STO-f) close to the p-type interface (STO-f/LaAlO3), while oxygen vacancies prevail close to the top n-type interface (LaAlO3/STO-f). At the same interface, misfit dislocations relax the tensile strain of the top LaAlO3 layer. Combining x-ray absorption spectroscopy, x-ray linear dichroism, resonant photoemission spectroscopy, and electron energy loss spectroscopy, we observe that the 3d orbital reconstruction at the interface between LaAlO3 and the SrTiO3 substrate is confined over a few interfacial Ti planes while, at the top n-type interface (LaAlO3/STO-f), the absence of a dichroic signal can be related to the blurring of the interfacial orbital reconstruction due to the heterogeneity of defects. [ABSTRACT FROM AUTHOR]

Published
2020
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38. Direct Evidence of Fe2+-Fe3+ Charge Ordering in the ferrimagnetic Hematite-Ilmenite Fe1.35Ti0.65O3 -d Thin Films

Author

Bocher, Laura, Popova, Elena, Nolan, M., Chikoidze, E., Gloter, Alexandre, March, K., Berini, Bruno, Stéphan, Odile, Keller, Niels, Dumont, Yves, Laboratoire de Physique des Solides (LPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Groupe d'Etude de la Matière Condensée (GEMAC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Tyndall National Institute, and University College Cork (UCC)

Subjects
75.47.Lx, 71.15.Mb, 75.25.Dk, 79.20.Uv, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]
Abstract

International audience; In this Letter we highlight direct experimental evidence of Fe2+-Fe3+ charge ordering at room temperature in hematite-ilmenite Fe1.35Ti0.65O3 -d epitaxial thin films grown by pulsed laser deposition, using aberration-corrected scanning transmission electron microscopy coupled to high-resolution energy electron-loss spectroscopy. These advanced spectromicroscopy techniques demonstrate a strong modulation of the Fe2+ valence state along the c axis. Density functional theory calculations provide crucial information on the key role of oxygen vacancies in the observed charge distributions. Their presence at significant levels leads to the localization of extra electrons onto reduced Fe2+ sites, while Ti remains solely 4+. The magnetic and transport properties of these films are reviewed in the light of the present results regarding their ferrimagnetic character correlated with the Fe2+ modulation and their semiconducting behavior interpreted by an Efros-Shklovskii variable-range hopping conduction regime via Fe2+ and Fe3+ centers. The experimental evidence of only one type of mixed valence state, i.e., Fe2+ and Fe3+, in the Fe2 xTixO3-d system will thus help to interpret further the origin of its geomagnetic properties and to illuminate fundamental issues regarding its spintronic potential.

Published
2013
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44. Tailored nanoscale plasmon-enhanced vibrational electron spectroscopy.

Author

Tizei, Luiz H. G., Mkhitaryan, Vahagn, Lourenço-Martins, Hugo, Scarabelli, Leonardo, Watanabe, Kenji, Taniguchi, Takashi, Tencé, Marcel, Blazit, Jean-Denis, Li, Xiaoyan, Woo, Steffi Y., Gloter, Alexandre, Zobelli, Alberto, Schmidt, Franz, Garcia de Abajo, F. Javier, Liz-Marzán, Luis M., Stéphan, Odile, and Kociak, Mathieu

Published
2021
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46. Magnetization Reversal in CsNiIICrIII(CN)6 Coordination Nanoparticles: Unravelling Surface Anisotropy and Dipolar Interaction Effects.

Author

Prado, Yoann, Mazerat, Sandra, Rivière, Eric, Rogez, Guillaume, Gloter, Alexandre, Stéphan, Odile, Catala, Laure, and Mallah, Talal

Subjects
NANOPARTICLES, MAGNETIZATION reversal, ANISOTROPY, ACTIVATION energy
Abstract

CsNiCr(CN)6 coordination nanoparticles with sizes ranging from 6 to 30 nm are highly diluted in an organic polymer matrix. Their static and dynamic magnetic behaviour allows unravelling of surface anisotropy and interparticle dipolar interaction effects. The single magnetic domain critical size is thus evaluated to be around 22 nm with a blocking temperature of 21 K (at ν = 1 Hz) and an effective energy barrier for the reversal of the magnetization of 426 K. [ABSTRACT FROM AUTHOR]

Published
2014
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47. Mapping plasmons at the nanometer scale in an electron microscope.

Author

Kociak, Mathieu and Stéphan, Odile

Subjects
*PLASMONICS, *NANOELECTROMECHANICAL systems, *ELECTRON microscopes, *ELECTRON energy loss spectroscopy, *CATHODOLUMINESCENCE, *SPECTRUM analysis, *SURFACE plasmons, *METAL nanoparticles
Abstract

In this tutorial review, we present the use of electron energy loss spectroscopy (EELS) and cathodoluminescence (CL) spectroscopy for surface plasmon mapping within metallic nanoparticles. We put a special emphasis on particles that are much smaller than the wavelength of visible light. We start by introducing the concept of surface plasmons, keeping the formalism as simple as possible by focusing on the quasi-static approximation. We then make a link between optical cross-sections, EELS and CL probabilities, and the surface plasmons' physical properties. A short survey of simulation tools is given. We then present typical experimental set-ups and describe some problems frequently encountered with spectrometers. Experimental conditions for improved signal to noise ratio are discussed. Analysis techniques are discussed, especially those related to the spectral imaging mode, which is extremely useful in EELS and CL experiments. Finally, the specific range of applications of EELS and CL with respect to other nano-optic techniques is discussed, as well as the strengths and weaknesses of EELS as compared with CL. [ABSTRACT FROM AUTHOR]

Published
2014
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49. A Top-Down Synthesis Route to Ultrasmall Multifunctional Gd-Based Silica Nanoparticles for Theranostic Applications.

Author

Mignot, Anna, Truillet, Charles, Lux, François, Sancey, Lucie, Louis, Cédric, Denat, Franck, Boschetti, Frédéric, Bocher, Laura, Gloter, Alexandre, Stéphan, Odile, Antoine, Rodolphe, Dugourd, Philippe, Luneau, Dominique, Novitchi, Ghenadie, Figueiredo, Leandro Carlos, de Morais, Paulo Cesar, Bonneviot, Laurent, Albela, Belen, Ribot, François, and Van Lokeren, Luk

Abstract

New, ultrasmall nanoparticles with sizes below 5 nm have been obtained. These small rigid platforms (SRP) are composed of a polysiloxane matrix with DOTAGA (1,4,7,10-tetraazacyclododecane-1-glutaric anhydride-4,7,10-triacetic acid)-Gd3+ chelates on their surface. They have been synthesised by an original top-down process: 1) formation of a gadolinium oxide Gd2O3 core, 2) encapsulation in a polysiloxane shell grafted with DOTAGA ligands, 3) dissolution of the gadolinium oxide core due to chelation of Gd3+ by DOTAGA ligands and 4) polysiloxane fragmentation. These nanoparticles have been fully characterised using photon correlation spectroscopy (PCS), transmission electron microscopy (TEM), a superconducting quantum interference device (SQUID) and electron paramagnetic resonance (EPR) to demonstrate the dissolution of the oxide core and by inductively coupled plasma mass spectrometry (ICP-MS), mass spectrometry, fluorescence spectroscopy, 29Si solid-state NMR, 1H NMR and diffusion ordered spectroscopy (DOSY) to determine the nanoparticle composition. Relaxivity measurements gave a longitudinal relaxivity r1 of 11.9 s−1 m M−1 per Gd at 60 MHz. Finally, potentiometric titrations showed that Gd3+ is strongly chelated to DOTAGA (complexation constant log β110=24.78) and cellular tests confirmed the that nanoconstructs had a very low toxicity. Moreover, SRPs are excreted from the body by renal clearance. Their efficiency as contrast agents for MRI has been proved and they are promising candidates as sensitising agents for image-guided radiotherapy. [ABSTRACT FROM AUTHOR]

Published
2013
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