L2C
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Laboratoire Charles Coulomb UMR 5221 CNRS/UM2 (L2C)http://www.coulomb.univmontp2.fr/plugins/kitcnrs5.3/images/logo_small_l2c.jpg
https://www.coulomb.univmontp2.fr/
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#physique  Seminar of BAITY JESI Marco: Activated Dynamics in Glasses
https://www.coulomb.univmontp2.fr/?page=seminaires&id_seminar=782&details=1
20170911T12:51:15Z20170911T12:51:15Ztext/htmlenBAITY JESI MarcoIf a liquid is cooled fast enough, it is possible to avoid the phase transition towards a crystalline solid, and the system enters a metastable state, called supercooled liquid. If the cooling continues, the viscosity and the relaxation times grow so steeply that the system becomes effectively solid, even though the system did not undergo any thermodynamic phase transition. Such a solid is called a glass. Glassy materials appear in both in everyday life and in hightech devices. Further, many systems in biology, computer science and mathematics also exhibit a glassy behavior. In this talk, we try to understand the mechanisms underlying the rigidity of glasses. In phase space, the dynamics of such systems can be regarded as a random walk in a highdimensional energy landscape. This landscape is rugged, so in order to sample new configurations the system must 'hop' over an energy barrier from one local minimum (basin) to another. This type of process is called activation. We adopt a bottomup strategy to understand this phenomenon. We start from the simplest models, attempt to fully characterize the behavior of their random walk in phase space, and only then add features representing more realistic glasses. We analyze three paradigmatic meanfield models: the Trap Model, the Random Energy Model (REM) and the pspin model. In particular, in the REM, we see that despite the motion in configuration space is complex on intermediate timescales, there is a very large separation of time scales that washes out correlations induced by the exploration of the landscape. As a result, by coarsegraining the dynamical evolution in terms of basins of the energy landscape, the dynamics can be effectively described through a hopping between disconnected traps. This type of description is not applicable anymore in systems with a higher degree of correlation in the energy landscape, such as the pspin model, where the energy landscape exhibits large basins which are connected one to the other through nontrivial boundaries.#physique  Seminar of NINARELLO Andrea: Computer simulations of supercooled liquids near the experimental glass transition
https://www.coulomb.univmontp2.fr/?page=seminaires&id_seminar=784&details=1
20170912T14:15:32Z20170912T14:15:32Ztext/htmlenNINARELLO AndreaUnderstanding the mechanisms that lead to glass formation is one of the open problems for the condensed matter research. Numerous questions remain unanswered, because the tremendous increase of relaxation times during the cooling process prevents the exploration of equilibrium properties of supercooled liquids at very low temperature. Computer simulations of glassforming liquids are nowadays able to reach equilibrium at temperatures comparable to the ModeCoupling crossover temperature, which is well above the experimental glass transition temperature. As a consequence, simulations lag eight orders of magnitude behind experiments in terms of equilibration times. Progress to close this gap has been slow, and stems mostly from hardware improvements. In this thesis we make an important step to close this gap. We combine the use of a Monte Carlo algorithm, known as the swap algorithm, with the design of novel glassforming models. We systematically test numerous models using both discrete mixtures and polydisperse systems. We discuss the role that polydispersity and particle softness play in avoiding crystallization and in efficiently reaching previously unexplored regimes. We study the dynamical processes taking place during swap Monte Carlo simulations. We demonstrate that in some cases our technique is able to produce thermalized configurations at temperatures inaccessible even by experiments. In this newly accessible regime, we investigate some open questions concerning the glass transition. We show that a hard sphere fluid can be equilibrated at, and even beyond, the jamming packing fraction. We measure the configurational entropy in extremely supercooled liquid, finding a strong dimensional dependence that supports, on the one hand, the existence of an ideal glass transition at a finite temperature in three dimensions and, on the other hand, its absence in two dimensions. We detect the increase of amorphous order quantified through a static pointtoset length throughout the glass formation. We measure the critical exponents introduced in the meanfield theory of glasses much closer to the supposed ideal glass transition. Finally, we reveal the absence of a sharp geometric transition in the potential energy landscape across the ModeCoupling crossover. The models and the algorithms developed in this thesis shift the computational studies of glassforming liquids to an entirely new territory, which should help to close the gap between theory and experiments, and get us closer to solve the longstanding problem of the glass transition.#physique  Seminar of MIKHAILOVSKAYA Alesya: Experimental evidence of nonaffine deformations in disordered materials
https://www.coulomb.univmontp2.fr/?page=seminaires&id_seminar=775&details=1
20170829T14:39:30Z20170829T14:39:30Ztext/htmlenMIKHAILOVSKAYA Alesya(ART) The quantumoptics Hamiltonian in the Multipolar gauge.
https://www.coulomb.univmontp2.fr/?page=publications&ref_preprint=L2C:17105&details=1
20170910T22:00:00Z20170910T22:00:00Ztext/htmlenThis article deals with the fundamental problem of lightmatter interaction in the quantum theory. Although it is described through the vector potential in quantum electrodynamics, it is believed by some that a hamiltonian involving only the electric and the magnetic fields is preferable. In the literature this hamiltonian is known as the PowerZienauWoolley hamiltonian. We question its validity and show that it is not equivalent to the minimalcoupling hamiltonian. In this article, we show that these two hamiltonians are not connected through a gauge transformation. We find that the gauge is not fixed in the PowerZienauWoolley hamiltonian. The interaction term is written in one gauge whereas the rest of the hamiltonian is written in another gauge. The PowerZienauWoolley hamiltonian and the minimalcoupling one are related through a unitary transformation that does not fulfill the gauge fixing constraints. Consequently, they predict different physical results. In this letter, we provide the correct quantum theory in the multipolar gauge with a hamiltonian involving only the physical fields.(ART) Ultralongrange dynamic correlations in a microscopic model for aging gels
https://www.coulomb.univmontp2.fr/?page=publications&ref_preprint=L2C:17097&details=1
20170910T22:00:00Z20170910T22:00:00Ztext/htmlenWe use largescale computer simulations to explore the nonequilibrium aging dynamics in a microscopic model for colloidal gels. We find that gelation resulting from a kineticallyarrested phase separation is accompanied by `anomalous' particle dynamics revealed by superdiffusive particle motion and compressed exponential relaxation of time correlation functions. Spatiotemporal analysis of the dynamics reveals intermittent heterogeneities producing spatial correlations over extremely large length scales. Our study is the first microscopicallyresolved model reproducing all features of the spontaneous aging dynamics observed experimentally in soft materials.(ART) Comment on "Brownian diffusion of a particle at an air/liquid interface: elastic (not viscous) response of the surface"
https://www.coulomb.univmontp2.fr/?page=publications&ref_preprint=L2C:17106&details=1
20170906T22:00:00Z20170906T22:00:00Ztext/htmlenN.A.GaAs/GaInAs/GaAlAs Hall sensors
https://www.coulomb.univmontp2.fr/GaAsGaInAsGaAlAsHallsensors
https://www.coulomb.univmontp2.fr/GaAsGaInAsGaAlAsHallsensors20101011T16:53:26Ztext/htmlenDavid CASSAGNE
<p>Hall sensors, based on GaAs/GaInAs/GaAlAs pseudomorphic heterostructures, can be used for metrological and microscopic applications like electricity metering or scanning magnetometer. <br class='autobr' />
Electricity metering. The thermal drift cancellation of the magnetic sensitivity of Hall sensors used for electricity metering was the purpose of an industrial contract with ITRONFrance and the main purpose of the E.R.T. project (Equipe de Recherche Technologique / ERT4 MatériauxµCapteursµSystèmes; (...)</p>

<a href="https://www.coulomb.univmontp2.fr/ThemeComposantsetCapteurs" rel="directory">Theme: Devices and Sensors</a>
Congress/Workshop from 20180115 to 20180117: Polymères et Océans 2018
https://po2018.wixsite.com/po2018]
19700101T00:00:00Z19700101T00:00:00ZenCongress/Workshop from 20180316 to 20180317: International Conference on BioMedical Photonics
https://christelleeve.wixsite.com/monsite]
19700101T00:00:00Z19700101T00:00:00ZenCongress/Workshop from 20180619 to 20180626: European Summer School on Scattering Applied to Soft Condensed Matter
https://indico.ill.fr/indico/event/86/]
19700101T00:00:00Z19700101T00:00:00Zen