Neutrons
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Neutrons

Le réacteur Orphée.

Les neutrons permettent de sonder la matière et leur sensibilité aux éléments légers et au magnétisme en font une sonde unique et originale. A l'IRAMIS , l’utilisation de la spectrométrie neutronique dans divers domaines de la recherche fondamentale et appliquée est développée au Laboratoire mixte CEA-CNRS Léon Brillouin à Saclay. L'activité scientifique propre du laboratoire peut se regrouper en trois secteurs sensiblement d'égale importance: la physico-chimie, les études structurales et de transition de phases, le magnétisme et la supraconductivité.


 

 

Neutron diffusion make possible to probe the matter and its sensitivity to the light elements and to magnetism make it a single and original probe. Within IRAMIS, neutron spectrometry is used in various fields in fundamental and applied research and is developed at the CEA-CNRS Laboratory Leon Brillouin (LLB) in Saclay. Neutrons are mainly intended for the study of condensed matter. The scientific activity of the laboratory belongs to three sectors of equal importance: physicochemistry, structural studies and phase transitions, magnetism and supraconductivity.

 

 
Neutrons

The Orphée reactor.

#110 - Màj : 28/06/2020
Technique (desc. gen.)
On its own and through the "Fédération Française de diffusion Neutronique", LLB is engaged on several instruments outside Saclay : D1B at ILL D23 at ILL IN6/Sharp at ILL IN12 at ILL IN13 at ILL IN22 at ILL LLB is starting the transfer to PSI of its best SANS machine : PA20. PA20 will restart to be open to user beginning of 2021.
Le réacteur Orphée a fourni des faisceau de neutrons dédiés à l'étude de la matière condensée de 1980 à 2019. Plus d'une vingtaine d'appareils de diffusion et diffraction de neutron de tout type étaient disponibles sur Orphée. On trouvera leur description sur cette page.
Contribution française à l'instrumentation ESS   Présentation de l'European Spallation Source L'ESS (European Spallation Source) est la source européenne à spallation de prochaine génération actuellement en construction à Lund (Suède). Utilisant un pulse de neutrons de longue durée (2.
The LLB is currently evaluating the performances which can be achieved with high brillance "Compact Accelerator-driven Neutron Source" (CANS). The aim is to be able to provide to the French neutron scattering community access to a suite of workshorse instruments on-par with the current LLB instruments at the horizon 2025. In 2019 a big step forward has been acheived with the demonstration of efficiency of this type of facility (see DRF highlight in French) 
Voir aussi
  DREAM: A versatile powder diffractometer with single crystal capabilities   Brief description DREAM is a time-of-flight diffractometer that is mainly dedicated to powder diffraction, but also offers single crystal capabilities.
Eros a versatile reflectometer
Reflectivity experiments have been performed on the Eros reflectometer at Saclay on very small pieces of glass. During this measurement, we did demonstrate our ability to obtain reflectivity curves down to values of 10-5 within a few hours. The curve obtain in this measurement is given on the first picture in red. The calculated Fresnel curve is represented in blue.
LLB is engaged at various levels in the construction of five spectrometers around ESS (European Spallation Source in Sweden) This is the Bifrost web page
LLB is engaged at various levels in the construction of five spectrometers around ESS (European Spallation Source in Sweden) This is the Cspec web page
LLB is engaged in the upgrade of IN6 through a CRG contract of type A. This upgrade will be performed during the 2019 shutdown of ILL, but LLB is already in charge of the IN6 spectrometer. The IN6-Sharp LLB team will welcome users as soon as the ILL reactor restarts (March 1st 2018). Details of the upgrade could be find in the following pdf file : Sharp_lancement fédération 16 mai_2017-V2.pdf
MAGiC: a polarised single crystal diffractometer   Brief description MAGiC is a polarized time-of-flight single-crystal diffractometer dedicated to the study of magnetic properties in both applied and purely fundamental systems. Its development and construction are supported by a French/German/Swiss consortium, relying on a mesh of unique and complementary technical and scientific expertise.
LLB is engaged at various levels in the construction of five spectrometers around ESS (European Spallation Source in Sweden). Skadi-2020-09.pdf
TiNi alloy is polymorphic. It exhibits a martensitic transition near room temperature between a cubic CsCl-type (austenite) and a monoclinic TiNi-type (martensite) structure. This transformation is at the origin of its shape memory effect. In addition, TiNi has good hydrogen storage properties under normal conditions of pressure and temperature. In austenic form, TiNi absorbs 1.4 H/f.u. under atmospheric pressure.
The improvement of the mechanical properties of polymer films by inclusion of mineral particles is a well known industrial practice used since the end of the XIX century. A classical example is the rubber industry for which the addition of carbon black as fillers permits to increase the elastic modulus of the pneumatics. Nevertheless, the mechanisms which govern the reinforcement properties are still not completely described by experiments and theory.
Using conjugated polymers as the active materials in electronic and optoelectronic devices opens up the possibility of fabricating all-polymer devices using solution processing technologies. The fabrication of good quality field-effect transistors (FETs) is crucial to a number of polymer-based devices, such as active matrix displays and integrated circuits. Central to FET operation is the dielectric/semiconductor interface.
Light-harvesting antennae are pigment-protein complexes involved in light-absorption and excitation energy transfer (EET) to the so-called "reaction center" complexes, where the photochemical processes of photosynthesis take place. C-phycocyanin (C-PC) is one component of the phycobilisome, the light-harvesting system of cyanobacteria [1]. In phycobilisomes, EET is a highly efficient key event [2-3], where light-induced dynamics of the antenna pigment/protein complexes may play a role [4-7].
I.V. Golosovsky1, I. Mirebeau2, G. André2, D. A. Kurdyukov3, Yu. A. Kumzerov3,
1: St. Petersburg Nuclear Physics Institute, 188350, Gatchina, St. Petersburg, Russia 2: Laboratoire Léon Brillouin, CE-Saclay, F-91191, Gif-sur-Yvette, France 3: A. F. Ioffe Physico-Technical Institute, 194021, St. Petersburg, Russia 4: Rostov State University, 344090, Rostov/Don, Russia The properties of magnetics confined in nanometer scale cavities drastically differ from those in the bulk material.
Les nanoaimants moléculaires forment des systèmes magnétiques discrets isolés, composés d’un nombre fini d’atomes magnétiques, qui présentent donc des effets quantiques par rapport aux systèmes classiques de dimension infinie.
The strongly interacting conduction electrons can be accurately represented as a gas of weakly interacting electron-like excitations. This description, known as Fermi liquid theory, works for many metallic systems. However, over the past two decades, new types of metallic materials with strongly correlated electrons have been discovered that do not fit this standard description. The list includes the superconducting copper oxides and many other materials. More...
Hidden degrees of freedom in aperiodic crystals.
Following the synthesis by the ribosome, to carry out its biological function, a protein much fold into a single, well defined conformational state: the native state. Protein folding is thus the physico-chemical process by which a polypeptidic chain undergoes a structural change from an ensemble of coil like structure up to the unique structure encoded in its amino-acid sequence. This process is fascinating and remains one of the most challenging problems of structural biology.
This study investigates the long term behavior of glasses used for confinement of nuclear wastes. The results have been obtained from a fruitful collaboration between different CEA laboratories (LLB, LIONS, CEA Marcoule) and the Ecole Polytechnique. The corrosion process of the glasses by water creates at the glass surfaces, an alteration porous layer, hydrated and amorphous, called "gel".
BiFeO3 is a multiferroic materials in which ferroelectric and anti-ferromagnetic orders coexist well above room temperature (TN=643 K, TC=1093 K), with a high polarization (over 100 μC/cm2 [1]). We have shown at the LLB by neutron diffraction that these two order parameters interact and that the magnetization of the material can be modified by the application of an electric field.
In 1893 Sir William Armstrong reported a remarkable experiment: if a high voltage is established between two wine-glasses filled to the brim with pure water and connected by a cotton  thread, a rope of water is formed and remains suspended between the lips of the two glasses. This "water bridge" can subsist for a few seconds even once the thread has been removed [1].
  In the pyrochlore compounds R2Mo2O7, both rare earth R3+ and M4+ transition metal ions form a threedimensional network of corner sharing tetrahedra. The pyrochlore lattice is geometrically frustrated both for antiferromagnetic (AF) and ferromagnetic (F) nearestneighbour exchange interactions, leading to intriguing magnetic states such as spin liquids, spin ices or chemically ordered spin glasses.
C. BETTONI
Le Groupe d’Analyse Elémentaire, au sein du Laboratoire Pierre Süe est relié à deux réacteurs nucléaires et produit, en plus du diagnostic élémentaire, des éléments radioactifs par activation pour des laboratoires de recherche nationaux et internationaux.
The use of agricultural resources for industrial purposes will undoubtly be one of the major challenges of the 21 st century. Organic biosynthons used in chemistry should progressively replace those coming from fossil fuels. Our work on dispersions of fatty acids and hydroxylated derivatives forms part of these efforts in that it seeks to demonstrate the potential contribution of fatty acids (which may be extracted from plants) as a new class of surface active agents.
The concept of "spin ladder" originally appeared to study the theoretically still controversial antiferromagnet (AF) 2D square lattice in high temperature superconducting cuprates starting from a well understood 1D AF chain [1-2]. They can been schematized as an array of finite number of coupled chains .
This work is part of a theoretical project which aims to unravel the mechanism at work in the high temperature cuprate superconductors. In the recent article [1] we have studied the role of spin fluctuations, and namely of the collective spin mode, for the superconducting pairing and numerous electronic anomalies observed in cuprates.
Le magnétisme est un domaine d’intérêt majeur, car combiné à l’électronique, il a modifié en profondeur notre vie quotidienne : sous forme de capteurs, d’actionneurs, de dispositifs nomades (téléphones, tablettes, ordinateurs portables), de matériaux aux capacités de stockage accrues pour l'enregistrement magnétique de toutes nos données informatiques., etc...
The pseudogap region of the phase diagram is an important unsolved puzzle in the field of hightransition-temperature (Tc) superconductivity, characterized by anomalous physical properties below a certain temperature, T*[1]. In contrast to the superconducting temperature Tc which exhibits a dome-like shape, the pseudogap phase is observed only at low doping in the underdoped region of the cuprates phase diagram.
Faits marquants scientifiques
10 novembre 2020
Chang Liu, Wenxian Hu, Hanqiu Jiang, Guoming Liu*, Charles C. Han, Henning Sirringhaus, François Boué, and Dujin Wang The determination of intrinsic chain stiffness of conjugated polymers is challenging, in particular, for scattering techniques because of their strong light absorption and structural instability due to the complicated intra-/intermolecular interactions.
20 octobre 2020
K. Beauvois, V. Simonet, S. Petit, J. Robert, F. Bourdarot, M. Gospodinov, A.A. Mukhin, R. Ballou, V. Skumryev, and E. Ressouche The research field of magnetic frustration is dominated by triangle-based lattices but exotic phenomena can also be observed in pentagonal networks. A peculiar noncollinear magnetic order is indeed known to be stabilized in Bi2Fe4O9 materializing a Cairo pentagonal lattice.
28 septembre 2020
Li Shi, Florent Carn, Arsen Goukassov, Eric Buhler, and François Boué Mixing negatively charged polyelectrolyte (PEL) with positively charged gold nanoparticles (Au NPs) in aqueous solution results in electrostatics complexes of different shapes and compactness. Here, when complexing with a semirigid PEL hyaluronic acid (HA), we obtain crystals made of nanoparticles in a new region of the phase diagram, as evidenced by small-angle Xray scattering (SAXS).
02 septembre 2020
Marine Le Goas, Tom Roussel, Maria Kalbazova, David Carrière, Elodie Barruet, Valerie Geertsen, Giulia C. Fadda, Fabienne Testard, Geraldine Carrot and Jean-Philippe Renault Nanomedicines are considered as promising therapeutics for cancer treatment. However, clinical translation is still scarce, partly because their biological behavior is not well understood.
21 juillet 2020
Premakumar Yanda, I. V. Golosovsky, I. Mirebeau, N. V. Ter-Oganessian, Juan Rodríguez-Carvajal and A. Sundaresan In most of the spin-induced multiferroics, the ferroelectricity is caused by inversion symmetry breaking by complex spin structures of the transition-metal ions. Here, we report the importance of interplay of 4 f -3d magnetic interactions in inducing ferroelectricity in the centrosymmetric (Pnma) green phase compound Gd2BaCuO5.
23 juin 2020
We show by X-ray and neutron small-angle scattering that gold nanoparticles with controlled sizes and morphologies can be obtained by the metallic reduction of AuCl4– ions trapped in 3D organic molds by X-ray radiolysis. The molds are spherical frozen micelles of polystyrene-b-poly(dimethylaminoethyl methacrylate) (PS-b-PDMAEMA) block copolymer in acidic aqueous solution with a PS spherical core surrounded by a corona of PDMAEMA chains in good solvent.
09 mai 2020
Andrew M. Jimenez, Dan Zhao, Kyle Misquitta, Jacques Jestin and Sanat K. Kumar Understanding the structure and dynamics of the bound polymer layer (BL) that forms on favorably interacting nanoparticles (NPs) is critical to revealing the mechanisms responsible for material property enhancements in polymer nanocomposites (PNCs).
15 avril 2020
La recherche de nouveaux états de la matière, allant au-delà de la description classique "à la Landau" suscite un très fort engouement en physique.
08 avril 2020
Aline Maire du Poset, Mikaela Börjesson, Céline Rameau, Claire Madeleine-Perdrillat, Adrien Lerbret, Camille Loupiac, Fabrice Cousin, Ali Assifaoui We show here how the structure of polygalacturonate (polyGalA) hydrogels cross-linked by Ca2+ cations via external gelation controls the loading and release rate of beta-lactoglobulin (BLG), a globular protein.
17 mars 2020
A. C. Ferreira, S. Paofai, A. Létoublon, J. Ollivier, S. Raymond, B. Hehlen, B. Rufflé, S. Cordier, C. Katan, J. Even & P. Bourges   Hybrid organolead perovskites (HOP) have started to establish themselves in the field of photovoltaics, mainly due to their great optoelectronic properties and steadily improving solar cell efficiency. Study of the lattice dynamics is key in understanding the electron-phonon interactions at play, responsible for such properties.
13 février 2020
de Oliveira-Silva, Rodrigo; Bélime, Agathe; Le Coeur, Clémence; Chennevière, Alexis; Helary, Arnaud; Cousin, Fabrice; Judeinstein, Patrick; Sakellariou, Dimitrios; Zanotti, Jean-Marc In soft condensed matter, Small Angle Neutron Scattering (SANS) is a central tool to probe structures with characteristic sizes ranging from 1 to 100 nm. However, when used as a standalone technique, the dynamic properties of the sample are not accessible.
14 janvier 2020
N. Martin, M. Deutsch, T. C. Hansen, M. T. Fernandez-Diaz, L. N. Fomicheva, A. V. Tsvyashchenko, and I. Mirebeau In the MnGe chiral magnet, the helimagnetic order and local moment collapse in two steps, showing the succession of high spin (HS) and low spin (LS) states as pressure increases. Here, we use high-pressure neutron diffraction to study the doped compounds Mn0.86Co0.14Ge and Mn0.9Rh0.1Ge, and show that the evolution of their microscopic magnetic properties is instead continuous.
21 décembre 2019
M. Ruminy, S. Guitteny, J. Robert, L.-P. Regnault, M. Boehm, P. Steffens, H. Mutka, J. Ollivier, U. Stuhr, J. S. White, B. Roessli, L. Bovo, C. Decorse, M. K. Haas, R. J. Cava, I. Mirebeau, M. Kenzelmann, S. Petit, and T. Fennell Tb2Ti2O7 presents an ongoing conundrum in the study of rare-earth pyrochlores.
25 novembre 2019
A. S. Sukhanov, Praveen Vir, A. S. Cameron, H. C. Wu, N. Martin, S. Mühlbauer, A. Heinemann, H. D. Yang, C. Felser, and D. S. Inosov The cubic chiral helimagnets with the P213 space group represent a group of compounds in which the stable skyrmion-lattice state is experimentally observed. The key parameter that controls the energy landscape of such systems and determines the emergence of a topologically nontrivial magnetic structure is the Dzyaloshinskii-Moriya interaction (DMI).
23 octobre 2019
N. Martin, I. Mirebeau, C. Franz, G. Chaboussant, L. N. Fomicheva, and A. V. Tsvyashchenko We study the helimagnetic ground state of the MnGe cubic alloy using small-angle neutron scattering and a high-resolution method, the so-called MIEZE spectroscopy. Upon cooling below the Néel temperature TN = 170(5) K, we observe the proliferation of long-wavelength gapless spin fluctuations, concomitant with a continuous evolution of the helical correlation length.
25 septembre 2019
La physique de la matière condensée repose sur quelques concepts fondateurs, comme le paradigme de Néel (avec sa description des ordres magnétiques classiques), la théorie des liquides de Fermi (avec le concept de quasi-particule), et la théorie de Landau des transitions de phases (mettant en exergue le concept de brisure spontanée de symétrie).
22 septembre 2019
Daniela Russo, Maya Dimova Lambreva, Christiane Alba Simionesco, Pierre Sebban,and Giuseppina Rea Studies on the dynamical properties of photosynthetic membranes of land plants and purple bacteria have been previously performed by neutron spectroscopy, revealing a tight coupling between specific photochemical reactions and macromolecular dynamics.
27 août 2019
D. Russo, A. De Angelis, A. Paciaroni, B. Frick, N. de Sousa, F. R. Wurm, and J. Teixeira We investigate the relaxation dynamics of protein−polymer conjugates by neutron scattering spectroscopy to understand to which extent the coating of a protein by a polymer can replace water in promoting thermal structural fluctuations.
19 juillet 2019
The response of a position-sensitive Li-glass scintillator detector to alpha-particles from a collimated 241Am source scanned across the face of the detector has been measured. Scintillation light was read out by an 8x8 pixel multi-anode photomultiplier and the signal amplitude for each pixel has been recorded for every position on a scan. The pixel signal is strongly dependent on position and in general several pixels will register a signal (a hit) above a given threshold.
20 juin 2019
A. Theodoratou, L.-T. Lee, J. Oberdisse and A. Aubert-Pouëssel, Langmuir 35(20) (2019) 6620. Abstract : Nanofilms of about 2 nm thickness have been formed at the air–water interface using functionalized castor oil (ICO) with cross-linkable silylated groups.
30 mai 2019
"Dynamics properties of photosynthetic microorganisms probed by incoherent neutron scattering" Daniela Russo, Maya Dimova Lambreva, Christiane Alba Simionesco, Pierre Sebban, and Giuseppina Rea Biophysical Journal, 116 (9) (2019) 1759-1768 Studies on the dynamical properties of photosynthetic membranes of land plants and purple bacteria have been previously performed by neutron spectroscopy, revealing a tight coupling between specific photochemical reactions and macromolecular dynamics.
04 mai 2019
B. Annighöfer , A. Hélary, A. Brulet, A. Colas de la Noue, C. Loupiac and S. Combet Review of Scientific Instruments 90 (2019) 025106 Abstract : We report on a high pressure (HP) cell designed for the determination of the structure of molecular solutions by small-angle neutron scattering (SANS). The HP cell is fitted up with two thick metallic windows that make the device very resistant under hydrostatic pressures up to 600 MPa (or 6 kbar).
21 avril 2019
Les membranes d’oxyde d’aluminium nanoporeuses sont des systèmes modèles permettant d’étudier le comportement de la matière sous confinement. Leurs utilisations pour des études de nano-moulage, de microfluidique ou en biologie sont ainsi nombreuses.
05 mars 2019
Annelies Sels, Giovanni Salassa, Fabrice Cousin, Lay-Theng Lee, Thomas Bürgi, Nanoscale 26 (2018) 12754. Aromatic dithiol linkers were used to prepare aggregates of Au25(SR)18 clusters (SR: thiolate) via ligand exchange reactions. Fractions of different aggregate sizes were separated by size exclusion chromatography (SEC).
04 mars 2019
Marguerite Léang, Didier Lairez, Fabrice Cousin, Frédérique Giorgiutti-Dauphiné, Ludovic Pauchard, Lay-Theng Lee During evaporative drying of a colloidal dispersion, the structural behavior at the air-dispersion interface is of particular relevance to the understanding of the consolidation mechanism and the final structural and mechanical properties of the porous media.
15 février 2019
Burkhard Annighöfer, Arnaud Hélary, Annie Brûlet, Alexandre Colas de la Noue, Camille Loupiac, and Sophie Combet We report on a high pressure (HP) cell designed for the determination of the structure of molecular solutions by small-angle neutron scattering (SANS). The HP cell is fitted up with two thick metallic windows that make the device very resistant under hydrostatic pressures up to 600 MPa (or 6 kbar).
25 janvier 2019
M. Deutsch, W. Peng, P. Foury-Leylekian, V. Balédent, S. Chattopadhyay, M. T. Fernandez-Diaz, T. C. Hansen, A. Forget, D. Colson, M. Greenblatt, M.-B. Lepetit, S. Petit, and I. Mirebeau The magnetic structure of TbMn2O5 and DyMn2O5 multiferroics has been studied by high-pressure neutron diffraction in a large pressure range up to 6.6 GPa.
03 janvier 2019
Sophie Combet, Fabrice Cousin, Human Rezaei, Sylvie Noinville Soluble oligomers of prion proteins (PrP), produced during amyloid aggregation, have emerged as the primary neurotoxic species, instead of the fibrillar end-products, in transmissible spongiform encephalopathies. However, whether the membrane is among their direct targets, that mediate the downstream adverse effects, remains a question of debate.
12 décembre 2018
Souha Ben Mahmoud, Wafa Essafi, Annie Brûlet and François Boué The chain conformation in sulfonated polystyrene PSSNa of a degree of sulfonation 0.34 ≤ f ≤ 1, i.e., of various hydrophobicity, is followed in mixtures of water and increasing content of tetrahydrofuran (THF), a good solvent of the hydrophobic polystyrene moieties (which improves the solvent quality of the mixture).
20 novembre 2018
Jyotsana Lal This article is dedicated to the memory of Loic Auvray The results on Winsor phases, droplet and bicontinous microemulsions phases with polymer-grafted lipids studied by Small Angle Neutron Scattering (SANS) are reported below, together with the contrast variation techniques used to characterize the average curvature in the system.
15 octobre 2018
Raphael Dos Santos Morais, Olivier Delalande, Javier Perez, Dominique Mias-Lucquin, Melanie Lagarrigue, Anne Martel, Anne-Elisabeth Molza, Angelique Cheron, Celine Raguenes-Nicol, Thomas Chenuel, Arnaud Bondon, Marie-Sousai Appavou, Elisabeth Le Rumeur, Sophie Combet, and Jean-Francois Hubert Scaffolding proteins play important roles in supporting the plasma membrane (sarcolemma) of muscle cells.
24 septembre 2018
Fengjiao Qian, Lars J. Bannenberg, Heribert Wilhelm, Grégory Chaboussant, Lisa M. Debeer-Schmitt, Marcus P. Schmidt, Aisha Aqeel, Thomas T. M. Palstra, Ekkes Brück, Anton J. E. Lefering, Catherine Pappas, Maxim Mostovoy, Andrey O.
08 septembre 2018
Lien avec leurs propriétés photovoltaïques et maitrise de la séparation e--trou
Les cellules solaires à base de pérovskites présentent de fort rendement car elles permettent d'élargir la fraction du spectre solaire qui peut être converti en électricité. Ces performances sont directement liées à leur structure cristalline bien particulière, dont les propriétés de vibrations ont été étudiées par diffusion de neutrons.
29 août 2018
I. Mirebeau, N. Martin, M. Deutsch, L. J. Bannenberg, C. Pappas, G. Chaboussant, R. Cubitt, C. Decorse, and A. O. Leonov Reentrant spin glasses are frustrated disordered ferromagnets developing vortexlike textures under an applied magnetic field. Our study of a Ni0.81Mn0.19Ni0.81Mn0.19 single crystal by small angle neutron scattering clarifies their internal structure and shows that these textures are randomly distributed.
09 août 2018
Maelenn Chevreuil, Didier Law-Hine, Jingzhi Chen, Stéphane Bressanelli, Sophie Combet, Doru Constantin, Jéril Degrouard, Johannes Möller, Mehdi Zeghal and Guillaume Tresset The survival of viruses partly relies on their ability to self-assemble inside host cells. Although coarse-grained simulations have identified different pathways leading to assembled virions from their components, experimental evidence is severely lacking.
20 juin 2018
Unravelling a mechanism of action for a cecropin a‑melittin hybrid antimicrobial peptide: the induced formation of multilamellar lipid stacks T. Silva, B. Claro, B. F. B. Silva, N. Vale, P. Gomes, M.-S. Gomes, S. S. Funari, J. Teixeira, D. Uhríková, and M. Bastos, Langmuir, 2018, 34 (5), pp 2158–2170. An understanding of the mechanism of action of antimicrobial peptides is fundamental to the development of new and more active antibiotics.
28 mai 2018
Béatrice Gillon, Albert Hammerschmied, Arsen Gukasov, Alain Cousson, Thomas Cauchy, Eliseo Ruiz, John A. Schlueter, Jamie L. Manson We report neutron‐diffraction investigations of the quasi‐2D MnII(dca)2(pym)(H2O) (pym = N2C4H4) compound, where high‐spin MnII ions are bridged by dicyanamide anions, [N(CN)2]– (herein abbreviated dca). Inside the layers, Mn2+ ions are connected by single or double dca bridges.
22 mai 2018
Les transitions de phase sont des phénomènes physiques bien connus, qui font partie de notre vie quotidienne : l’eau liquide gèle à 0°c, bout à 100 °C ; certains métaux comme l’étain (étain blanc et étain gris) changent de structure cristalline en fonction de la température...
04 mai 2018
Anne-Sophie Robbes, Fabrice Cousin , Florian Meneau, and Jacques Jestin We probe by SANS the conformation of polymer chains of the matrix in various nanocomposites based on the same building blocks, namely spherical magnetic nanoparticles of maghemite (γ-Fe2O3) as fillers and polystyrene (PS) for the matrix.
17 avril 2018
We report on the self-assembly behavior of poly(2-methyl-2-oxazoline)–block–poly(2-octyl-2-oxazoline) comprising different terminal perfluoroalkyl fragments in aqueous solutions. As reported previously [Kaberov et al. (2017)] such polyphiles can form a plethora of nanostructures depending of the composition and on the way of preparation.
24 mars 2018
Cationic thermoresponsive poly(n-vinylcaprolactam) microgels synthesized by emulsion polymerization using a reactive cationic macro-raft agent L. Etchenausia, E. Deniau, A. Brûlet, J. Forcada and M. Save,  Macromolecules  (2018) sous presse.
22 février 2018
Magnetic skyrmions are topologically stable, vortex-like objects surrounded by chiral boundaries that separate a region of reversed magnetization from the surrounding magnetized material. They are closely related to nanoscopic chiral magnetic domain walls, which could be used as memory and logic elements for conventional and neuromorphic computing applications that go beyond Moore’s law.
21 décembre 2017
D. Bounoua, R. Saint-Martin, S. Petit, P. Berthet, F. Damay, Y. Sidis, F. Bourdarot, and L. Pinsard-Gaudart, Phys. Rev. B 95, 224429 The low energy magnetic excitations spectra of the pristine and doped quasi-one-dimensional spin chains cuprates SrCuO2 have been investigated by inelastic neutron scattering.
17 novembre 2017
A. K. Nayak, V. Kumar, T. Ma, P. Werner, E. Pippel, R. Sahoo, F. Damay, U. K. Rößler, C. Felser and S. S. P. Parkin,  Nature 548, 561–566. Magnetic skyrmions are topologically stable, vortex-like objects surrounded by chiral boundaries that separate a region of reversed magnetization from the surrounding magnetized material.
26 octobre 2017
Raphael Dos Santos Morais, Olivier Delalande, Javier Pérez, Liza Mouret, Arnaud Bondon, Anne Martel, Marie-Sousai Appavou, Elisabeth Le Rumeur, Jean-François Hubert, and Sophie Combet Obtaining structural information on integral or peripheral membrane proteins is currently arduous due to the difficulty of their solubilization, purification, and crystallization (for X-ray crystallography (XRC) application).
06 septembre 2017
Stehane Longeville et Laura-Roxana Stingaciu Translational diffusion of macromolecules in cell is generally assumed to be anomalous due high macromolecular crowding of the milieu. Red blood cells are a special case of cells filled quasi exclusively (95% of the dry weight of the cell) with an almost spherical protein: hemoglobin. Hemoglobin diffusion has since a long time been recognized as facilitating the rate of oxygen diffusion through a solution.
24 août 2017
Crystal-electric-field excitations and spin dynamics in Ce3Co4Sn13 semimetallic chiral-lattice phase Kazuaki Iwasa, Yuka Otomo, Kazuya Suyama, Keisuke Tomiyasu, Seiko Ohira-Kawamura, Kenji Nakajima, and Jean-Michel Mignot Inelastic neutron scattering experiments have been conducted to investigate the spin dynamics and crystal-electric-field level scheme of the Ce 4f4f electrons in Ce3Co4Sn13Ce3Co4Sn13 .
12 avril 2016
Pour atteindre des niveaux ultimes d'intégration à l'échelle nanométrique, de nouveaux matériaux moléculaires sont développés pour le stockage de l’information et la spintronique. L'étude de leur élaboration et leur caractérisation, en particulier celle du contrôle de leur anisotropie magnétique, sont alors essentiels.
29 septembre 2015
Après 30 années d'efforts de recherche, l'origine de la supraconductivité à haute température reste un des grands défis d'aujourd'hui en physique du solide. Les supraconducteurs à haute température sont plutôt de mauvais conducteurs électriques à la température ambiante.
17 novembre 2014
Au quotidien, les aimants permanents sont partout présents dans les dispositifs technologiques qui nous entourent. Aujourd’hui, il y en a 4 types principaux sur le marché mondial : NdFeB, ferrite, SmCo et AlNiCo, dont 65% contiennent des terres rares, essentiellement du néodyme.
15 novembre 2013
En matière condensée, les corrélations électroniques sous-tendent un grand nombre de phénomènes fondamentaux encore inexpliqués, dont certains peuvent déboucher sur de nouvelles applications (stockage de l'information, composants magnétiques, électronique de spin,…).
06 novembre 2013
Une équipe de l’Iramis a sondé à l’aide de neutrons le magnétisme d’un cobaltate isolant. Ô surprise, ce composé présente une propriété considérée jusque-là par la communauté scientifique comme la signature de supraconducteurs à haute température critique (cuprates).
26 avril 2013
Dans la conception du cœur d'un réacteur nucléaire, les matériaux de structure doivent être sélectionnés en ayant une bonne maitrise de leurs propriétés mécaniques et de leur tenue sous irradiation. La dispersion nanostructurée d'oxyde (aciers ODS : Oxide Dispersion Strengthening) est une méthode pour durcir les aciers.
18 mars 2013
Une collaboration Laboratoire Léon Brillouin – Service de Physique de l’Etat Condensé
   Le titanate de Terbium Tb2Ti2O7 est un oxyde isolant à réseau pyrochlore (un réseau spécial formé de tétraèdres se touchant par leurs sommets), dont la géométrie est telle que les ions magnétiques (les terres rares Tb) ne peuvent pas trouver de configuration de spin qui satisfasse toutes les interactions antiferromagnétiques en même temps.
20 décembre 2012
Les éléments magnétorésistifs peuvent être utilisés dans des mémoires magnétiques ou des capteurs magnétiques. L’obtention d’une couche ferromagnétique bloquée est une condition indispensable à la réalisation de ces applications et est maintenant bien développée dans le cas des métaux.
27 janvier 2012
Un des enjeux actuels de l’ingénierie moléculaire est le stockage de l’information à l'échelle de la molécule unique. Un point-clé dans ce domaine est la maîtrise des paramètres qui régissent l’anisotropie magnétique moléculaire.
14 octobre 2011
L'aimantation de tout matériau macroscopique n'est pas uniforme, mais constituée de domaines d'orientation magnétique distincte, séparés par des parois magnétiques, dont le déplacement pilote l'évolution de l'aimantation.
04 mars 2010
D. S. Inosov1, J. T. Park1, P. Bourges2, D. L. Sun1, Y. Sidis2, A. Schneidewind3,4, K. Hradil4,5, D.Haug1, C. T. Lin1, B. Keimer1, and V. Hinkov
1 Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany2 Laboratoire Léon Brillouin, CEA-CNRS, CEA Saclay, 91191 Gif-sur-Yvette, France3 Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM-II), TU München, D-85747 Garching, Germany A la grande surprise de la communauté scientifique, une supraconductivité à haute température critique (Tc > 50K) a été découverte en mars 2008 dans des composés à base de fer [1].
26 novembre 2009
H. Cao, A. Gukasov, I. Mirebeau, P. Bonville, C. Decorse, and G. Dhalenne
Dans les composés magnétiques géométriquement frustrés, l’état fondamental résulte d’un équilibre subtil entre différents termes d’énergie.  Des ordres magnétiques exotiques à courte portée, comme les glaces de spin ou les liquides de spin, peuvent être stabilisés, sans désordre chimique.
05 décembre 2008
Communiqué de presse commun CEA-CNRS Les molécules qui constituent un fluide sont tellement petites et nombreuses qu’à notre échelle nous pouvons considérer les fluides comme des milieux continus.
17 novembre 2008
Les chercheurs du LLB viennent de publier en 2008 plusieurs articles dans les prestigieuses revues Science [1-2] et Nature [3]. Ces résultats montrent toutes les potentialités des techniques de diffraction de neutrons à la pointe des études sur les nouveaux matériaux.
04 janvier 2008
(1,2) B. Toudic, P. Garcia, C. Odin, P. Rabiller, C. Ecolivet and E. Collet,
P. Bourges3, G.J. McIntyre4, M.D. Hollingsworth5, T. Breczewski6
1 Institut de Physique de Rennes, CNRS UMR 6251, Univ. Rennes 1, 35042 Rennes, France2 CNRS, UMR 6251, IPR, 263 Avenue du Général Leclerc, 35042 Rennes Cedex, France.3 Laboratoire Léon Brillouin, CEA-CNRS, CEA Saclay, 91191 Gif-sur-Yvette, France4 Institut Laue-Langevin, 38042 Grenoble Cedex 9, France.5 Department of Chemistry, Kansas State University, Manhattan, KS 66506, USA.6 Facultad de Ciencias, Universidad del Pais Vasco, Apdo 644, Bilbao, Spain.
11 avril 2007
S. Petit, F. Moussa, M. Hennion et S. Pailhès (DRECAM/LLB CEA-Saclay)
L. Pinsard-Godard, Laboratoire de Chimie du Solide, Paris XI
A. Ivanov, ILL, BP 156 F-38042 Grenoble
Les multi-ferroïques sont des matériaux qui possèdent la particularité rare d’avoir un état fondamental à la fois magnétique et ferro-électrique [1].
19 mai 2006
B. Fauque1, Y. Sidis1, V. Hinkov2, S. Pailhès1,3, C.T. Lin2, X. Chaud4, Ph. Bourges1 1Laboratoire Léon Brillouin, CEA-CNRS, CEA-Saclay, 91191 Gif sur Yvette, France 2MPI fur Festkorperforschung, Heisenbergstr. 1, 70569 Stuttgart, Germany 3LNS, ETH Zurich and Paul Scherrer Institute, CH–5232 Villigen PSI, Switzerland 4CRETA / CNRS, 25 Avenue des Martyrs, BP 166 38042 Grenoble cedex 9, France.

 

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