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232 results on '"Vernhet, D"'

1. Mastering disorder in a first-order transition by ion irradiation

Author

Cervera, S., LoBue, M., Fontana, E., Eddrief, M., Etgens, V. H., Lamour, E., Macé, S., Marangolo, M., Plouet, E., Prigent, C., Steydli, S., Vernhet, D., and Trassinelli, M.

Subjects
Condensed Matter - Materials Science
Abstract

The effect of ion bombardment on MnAs single crystalline thin films is studied. The role of elastic collisions between ions and atoms of the material is singled-out as the main process responsible for modifying the properties of the material. Thermal hysteresis suppression, and the loss of sharpness of the magneto-structural phase transition are studied as a function of different irradiation conditions. While the latter is shown to be associated with the ion induced disorder at the scale of the transition correlation length, the former is related to the coupling between disorder and the large-scale elastic field associated with the phase coexistence pattern.

Published
2023
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2. Modulating the phase transition temperature of giant magnetocaloric thin films by ion irradiation

Author

Cervera, S., Trassinelli, M, Marangolo, M, Carrétéro, C, Garcia, V, Hidki, S, Jacquet, E, Lamour, E, Lévy, A, Macé, S, Prigent, C, Rozet, J, Steydli, S, and Vernhet, D

Subjects
Physics - Applied Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Physics - Atomic Physics
Abstract

Magnetic refrigeration based on the magnetocaloric effect at room temperature is one of the most attractive alternative to the current gas compression/expansion method routinely employed. Nevertheless, in giant magnetocaloric materials, optimal refrigeration is restricted to the narrow temperature window of the phase transition (Tc). In this work, we present the possibility of varying this transition temperature into a same giant magnetocaloric material by ion irradiation. We demonstrate that the transition temperature of iron rhodium thin films can be tuned by the bombardment of ions of Ne 5+ with varying fluences up to 10 14 ions cm --2 , leading to optimal refrigeration over a large 270--380 K temperature window. The Tc modification is found to be due to the ion-induced disorder and to the density of new point-like defects. The variation of the phase transition temperature with the number of incident ions opens new perspectives in the conception of devices using giant magnetocaloric materials.

Published
2017
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3. Low energy Ne ion beam induced-modifications of magnetic properties in MnAs thin films

Author

Trassinelli, M, Carlsson, L Bernard, Cervera, S, Eddrief, M, Etgens, V, Gafton, V, Lacaze, E, Lamour, E, Lévy, M, Macé, S, Prigent, C., Rozet, J. -P., Steydli, S, Marangolo, M, and Vernhet, D

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

Investigations of the complex behavior of the magnetization of manganese arsenide thin films due to defects induced by irradiation of slow heavy ions are presented. In addition to the thermal hysteresis suppression already highlighted in M. Trassinelli et al., Appl. Phys. Lett. 104, 081906 (2014), we report here on new local magnetic features recorded by a magnetic force microscope at different temperatures close to the characteristic sample phase transition. Complementary measurements of the global magnetization measurements in different conditions (applied magnetic field and temperatures) enable to complete the film characterization. The obtained results suggest that the ion bombardment produces regions where the local mechanical constraints are significantly different from the average, promoting the local presence of magneto-structural phases far from the equilibrium. These regions could be responsible for the thermal hysteresis suppression previously reported, irradiation-induced defects acting as seeds in the phase transition.

Published
2016
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4. Hints on the origin of the thermal hysteresis suppression in giant magnetocaloric thin films irradiatied with highly charged ions

Author

Cervera, S, Trassinelli, M, Marangolo, M, Carlsson, L. Bernard, Eddrief, M, Etgens, Victor H., Gafton, V, Hidki, S, Lamour, E, Lévy, A, Macé, S, Prigent, C, Rozet, J. -P, Steydli, S, Zheng, Y, and Vernhet, D

Subjects
Condensed Matter - Materials Science, Physics - Atomic Physics
Abstract

In a recent experiment we demonstrated the possibility to suppress the thermal hysteresis of the phase transition in giant magnetocaloric MnAs thin film by interaction with slow highly charged ions (Ne 9+ at 90 keV) [1]. This phenomenon has a major impact for possible applications in magnetic refrigeration and thus its reproducibility and robustness are of prime importance. Here we present some new investigations about the origin and the nature of the irradiation-induced defects responsible for the thermal hysteresis suppression. Considering in particular two samples that receive different ion fluences (two order of magnitude of difference), we investigate the reliability of this process. The stability of the irradiation-induced defects with respect to a soft annealing is studied by X-ray diffraction and magnetometry measurements, which provide some new insights on the mechanisms involved.

Published
2015
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5. Mastering disorder in a first-order transition by ion irradiation

Author

Cervera, S., primary, LoBue, M., additional, Fontana, E., additional, Eddrief, M., additional, Etgens, V. H., additional, Lamour, E., additional, Macé, S., additional, Marangolo, M., additional, Plouet, E., additional, Prigent, C., additional, Steydli, S., additional, Vernhet, D., additional, and Trassinelli, M., additional

Published
2024
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6. Low intensity threshold values for keV X-ray production in laser-cluster interaction

Author

Prigent, C., Adoui, L., Lamour, E., Rozet, J. -P., Vernhet, D., Gobert, O., Meynadier, P., Normand, D., and Perdrix, M.

Subjects
Physics - Atomic and Molecular Clusters, Physics - Atomic Physics
Abstract

Absolute Ar XK (3 keV) and Xe XL (4 keV) photon yields are measured as a function of laser peak intensity, for large (104 - 105 atoms) argon and xenon clusters submitted to intense laser pulses. A clear threshold behavior is observed. The intensity threshold is found as low as 2 1014 Wcm-2, a value matching the production of singly-charged argon or doubly-charged xenon by optical field ionization. Possible mechanisms involved in the inner-shell ionization are discussed. The outcome on the optimization of keV X-ray production is underlined., Comment: 1 table, 4 figures. submitted to Physical Review Letters

Published
2005

7. Laser-cluster interaction: x-ray production by short laser pulses

Author

Deiss, C., Rohringer, N., Lamour, E., Prigent, C., Rozet, J. -P., Vernhet, D., and Burgdorfer, J.

Subjects
Physics - Atomic and Molecular Clusters
Abstract

We investigate the heating of the quasi-free electrons in large rare gas clusters (N exceeding 10^5 atoms) by short laser pulses at moderate intensities (I~10^{15} Wcm^{-2}). We identify elastic large-angle backscattering of electrons at ionic cores in the presence of a laser field as an efficient heating mechanism resembling the Fermi shuttle. Its efficiency as well as the effect of collective electron motion, electron-impact ionization and cluster charging, are studied employing a mean-field classical transport simulation. Results for the absolute x-ray yields are in surprisingly good quantitative agreement with recent experimental results., Comment: 5 pages,4 figures, submitted to Phys. Rev. Lett

Published
2005
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12. Surface chemistry of gold nanoparticles produced by laser ablation in pure and saline water

Author

Lévy, A. (Anna), De Anda Villa, M. (Manuel), Laurens, G. (Gaétan), Blanchet, V. (Valérie), Bozek, J. (John), Gaudin, J. (Jérȏme), Lamour, E. (Emily), Macé, S. (Stéphane), Mignon, P. (Pierre), Milosavljević, A. R. (Aleksandar R.), Nicolas, C. (Christophe), Patanen, M. (Minna), Prigent, C. (Christophe), Robert, E. (Emmanuel), Steydli, S. (Sébastien), Trassinelli, M. (Martino), Vernhet, D. (Dominique), Veteläinen, O. (Onni), Amans, D. (David), Lévy, A. (Anna), De Anda Villa, M. (Manuel), Laurens, G. (Gaétan), Blanchet, V. (Valérie), Bozek, J. (John), Gaudin, J. (Jérȏme), Lamour, E. (Emily), Macé, S. (Stéphane), Mignon, P. (Pierre), Milosavljević, A. R. (Aleksandar R.), Nicolas, C. (Christophe), Patanen, M. (Minna), Prigent, C. (Christophe), Robert, E. (Emmanuel), Steydli, S. (Sébastien), Trassinelli, M. (Martino), Vernhet, D. (Dominique), Veteläinen, O. (Onni), and Amans, D. (David)

Abstract

Pulsed laser ablation in liquid (PLAL) is a powerful method for producing nanoparticle colloids with a long-term stability despite the absence of stabilizing organic agents. The colloid stability involves different reactivities and chemical equilibria with complex ionic-specific effects at the nanoparticle/solvent interface which must be strongly influenced by their chemical composition. In this work, the surface composition of PLAL-produced gold nanoparticles in alkaline and saline (NaBr) water is investigated by X-ray photoelectron spectroscopy on free-flying nanoparticles, exempt from any substrate or radiation damage artifact. The Au 4f photoelectron spectra with a depth profiling investigation are used to evaluate the degree of nanoparticle surface oxidation. In alkaline water, the results preclude any surface oxidation contrary to the case of nanoparticles produced in NaBr solution. In addition, the analysis of Br 3d core-level photoelectron spectra agrees with a clear signature of Br on the nanoparticle surface, which is confirmed by a specific valence band feature. This experimental study is supported by DFT calculations, evaluating the energy balance of halide adsorption on different configurations of gold surfaces including oxidation or adsorbed salts.

Published
2021

14. Aurore:a platform for ultrafast sciences

Author

Fedorov, N. (N.), Beaulieu, S. (S.), Belsky, A. (A.), Blanchet, V. (V.), Bouillaud, R. (R.), De Anda Villa, M. (M.), Filippov, A. (A.), Fourment, C. (C.), Gaudin, J. (J.), Grisenti, R. (R.E.), Lamour, E. (E.), Lévy, A. (A.), Macé, S. (S.), Mairesse, Y. (Y.), Martin, P. (P.), Martinez, P. (P.), Noé, P. (P.), Papagiannouli, I. (I.), Patanen, M. (M.), Petit, S. (S.), Vernhet, D. (D.), Veyrinas, K. (K.), Descamps, D. (D.), Fedorov, N. (N.), Beaulieu, S. (S.), Belsky, A. (A.), Blanchet, V. (V.), Bouillaud, R. (R.), De Anda Villa, M. (M.), Filippov, A. (A.), Fourment, C. (C.), Gaudin, J. (J.), Grisenti, R. (R.E.), Lamour, E. (E.), Lévy, A. (A.), Macé, S. (S.), Mairesse, Y. (Y.), Martin, P. (P.), Martinez, P. (P.), Noé, P. (P.), Papagiannouli, I. (I.), Patanen, M. (M.), Petit, S. (S.), Vernhet, D. (D.), Veyrinas, K. (K.), and Descamps, D. (D.)

Abstract

We present the Aurore platform for ultrafast sciences. This platform is based on a unique 20 W, 1 kHz, 26 fs Ti:sapphire laser system designed for reliable operation and high intensity temporal contrast. The specific design ensures the high stability in terms of pulse duration, energy, and beam pointing necessary for extended experimental campaigns. The laser supplies 5 different beamlines, all dedicated to a specific field: attosecond science (Aurore 1), ultrafast phase transitions in solids (Aurore 2 and 3), ultrafast luminescence in solids (Aurore 4), and femtochemistry (Aurore 5). The technical specifications of these five beamlines are described in detail, and examples of the recent results are given.

Published
2020

15. Ion slowing down and charge exchange at small impact parameters selected by channeling: Superdensity effects

Author

L’Hoir, A., Adoui, L., Barrué, F., Billebaud, A., Bosch, F., Bräuning-Demian, A., Bräuning, H., Cassimi, A., Chevallier, M., Cohen, C., Dauvergne, D., Demonchy, C.E., Giot, L., Kirsch, R., Gumberidze, A., Kozhuharov, C., Liesen, D., Mittig, W., Mokler, P.H., Pita, S., Poizat, J.-C., Ray, C., Roussel-Chomaz, P., Rothard, H., Rozet, J.-P., Stöhlker, Th., Tarisien, M., Testa, E., Toleikis, S., Toulemonde, M., and Vernhet, D.

Published
2006
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16. Aurore: A platform for ultrafast sciences

Author

Fedorov, N., primary, Beaulieu, S., additional, Belsky, A., additional, Blanchet, V., additional, Bouillaud, R., additional, De Anda Villa, M., additional, Filippov, A., additional, Fourment, C., additional, Gaudin, J., additional, Grisenti, R. E., additional, Lamour, E., additional, Lévy, A., additional, Macé, S., additional, Mairesse, Y., additional, Martin, P., additional, Martinez, P., additional, Noé, P., additional, Papagiannouli, I., additional, Patanen, M., additional, Petit, S., additional, Vernhet, D., additional, Veyrinas, K., additional, and Descamps, D., additional

Published
2020
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17. The low energy beamline of the FISIC experiment: current status of construction and performance

Author

Schury, D, primary, Méry, A, additional, Ramillon, J M, additional, Adoui, L, additional, Chesnel, J-Y, additional, Lévy, A, additional, Macé, S, additional, Prigent, C, additional, Rangama, J, additional, Rousseau, P, additional, Steydli, S, additional, Trassinelli, M, additional, Vernhet, D, additional, Gumberidze, A, additional, Stöhlker, Th, additional, Bräuning-Demian, A, additional, Hahn, C, additional, Spillmann, U, additional, and Lamour, E, additional

Published
2020
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18. Ultrafast laser induced structural dynamics probed by time-resolved photoelectron spectroscopy

Author

Villa, M de Anda, primary, Lévy, A, additional, Gaudin, J, additional, Bouillaud, R, additional, Descamps, D, additional, Dorado, B, additional, Fedorov, N, additional, Grisenti, R, additional, Hatifi, M, additional, Jouin, H, additional, Lamour, E, additional, Macé, S, additional, Martin, P, additional, Petit, S, additional, Prigent, C, additional, Sobierajski, R, additional, Steydli, S, additional, Trassinelli, M, additional, Wawro, A, additional, and Vernhet, D, additional

Published
2020
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19. Surface chemistry of colloidal surfactant-free gold nanoparticles generated by laser ablation

Author

Lévy, A, primary, De Anda Villa, M, additional, Gaudin, J, additional, Amans, D, additional, Blanchet, V, additional, Boudjada, F, additional, Bozek, J D, additional, Grisenti, R E, additional, Lamour, E, additional, Laurens, G, additional, Macé, S, additional, Milosavljević, A R, additional, Nicolas, C, additional, Papagiannouli, I, additional, Patanen, M, additional, Prigent, C, additional, Robert, E, additional, Steydli, S, additional, Trassinelli, M, additional, and Vernhet, D, additional

Published
2020
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21. Assessing the surface oxidation state of free-standing gold nanoparticles produced by laser ablation

Author

De Anda Villa, M. (Manuel), Gaudin, J. (Jérôme), Amans, D. (David), Boudjada, F. (Fahima), Bozek, J. (John), Evaristo Grisenti, R. (Robert), Lamour, E. (Emily), Laurens, G. (Gaétan), Macé, S. (Stéphane), Nicolas, C. (Christophe), Papagiannouli, I. (Irene), Patanen, M. (Minna), Prigent, C. (Christophe), Robert, E. (Emmanuel), Steydli, S. (Sébastien), Trassinelli, M. (Martino), Vernhet, D. (Dominique), Lévy, A. (Anna), De Anda Villa, M. (Manuel), Gaudin, J. (Jérôme), Amans, D. (David), Boudjada, F. (Fahima), Bozek, J. (John), Evaristo Grisenti, R. (Robert), Lamour, E. (Emily), Laurens, G. (Gaétan), Macé, S. (Stéphane), Nicolas, C. (Christophe), Papagiannouli, I. (Irene), Patanen, M. (Minna), Prigent, C. (Christophe), Robert, E. (Emmanuel), Steydli, S. (Sébastien), Trassinelli, M. (Martino), Vernhet, D. (Dominique), and Lévy, A. (Anna)

Abstract

The surface chemistry of gold nanoparticles produced by the pulsed laser ablation in liquids method is investigated by X-ray photoelectron spectroscopy (XPS). The presence of surface oxide expected on these systems is investigated using synchrotron radiation in conditions close to their original state in solvent but free from substrate or solvent effects which could affect the interpretation of spectroscopic observations. For that purpose we performed the experiment on a controlled free-standing nanoparticle beam produced by combination of an atomizer and an aerodynamic lens system. These results are compared with those obtained by the standard situation of deposited nanoparticles on silicon substrate. An accurate analysis based on Bayesian statistics concludes that the existence of oxide in the free-standing conditions cannot be solely confirmed by the recorded core-level 4f spectra. If present, our data indicate an upper limit of 2.15 ± 0.68% of oxide. However, a higher credence to the hypothesis of its existence is brought by the structureless valence profile of the free-standing beam. Moreover, the cross-comparison with the deposited nanoparticles case clearly evidences an important misleading substrate effect. Experiment with free-standing nanoparticles is then demonstrated to be the right way to further investigate oxidation states on Au nanoparticles.

Published
2019

27. Methodology to account for load factor and availability during conceptual design phase of a gen IV nuclear power point

Author

Vernhet, D., LIBESSART, M., CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Airbus Defence and Space [Saint-Médard-en-Jalles], Airbus Defence and Space [Toulouse], and amplexor, amplexor

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], RAM, SFR, reliability, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], availability, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], maintenability, ASTRID
Abstract

International audience; Increasing availability is a permanent objective of the nuclear plant designers and operators.For ASTRID SFR project, this consideration was taken into account at the very beginning of the reactor conceptual design.The parameters on which the plant designer can focus their action are - The increase of the power production cycles duration,- The reduce of the refueling et inspection outages,- The increase of equipment reliability and parts availabilities.This overall work is conducted progressively and iteratively on all the ASTRID SFR reactor equipment and functions.This original work has led to - identify the functions or equipment on which it was necessary to focus in priority.- Question on equipment or function failure consequences (and the solution to avoid being a Driver).- Set reliability targets by system or function and to assess gap between the target and the current design.

Published
2016

28. Modulating the phase transition temperature of giant magnetocaloric thin films by ion irradiation

Author

Cervera, S., primary, Trassinelli, M., additional, Marangolo, M., additional, Carrétéro, C., additional, Garcia, V., additional, Hidki, S., additional, Jacquet, E., additional, Lamour, E., additional, Lévy, A., additional, Macé, S., additional, Prigent, C., additional, Rozet, J. P., additional, Steydli, S., additional, and Vernhet, D., additional

Published
2017
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29. Numerical simulations of purification and final charge state analysis of the slow ion beam for the FISIC project

Author

Kumar, A., primary, Méry, A., additional, Adoui, L., additional, Chesnel, JY., additional, Lévy, A., additional, Macé, S., additional, Prigent, C., additional, Ramillon, JM., additional, Rangama, J., additional, Rozet, JP., additional, Rousseau, P., additional, Steydli, S., additional, Trassinelli, M., additional, Vernhet, D., additional, and Lamour, E., additional

Published
2017
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30. Low energy Ne ion beam induced-modifications of magnetic properties in MnAs thin films

Author

Trassinelli, M, primary, Bernard Carlsson, L, additional, Cervera, S, additional, Eddrief, M, additional, Etgens, V H, additional, Gafton, E V, additional, Lacaze, E, additional, Lamour, E, additional, Lévy, A, additional, Macé, S, additional, Prigent, C, additional, Rozet, J-P, additional, Steydli, S, additional, Marangolo, M, additional, and Vernhet, D, additional

Published
2016
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35. Hints on the origin of the thermal hysteresis suppression in giant magnetocaloric thin films irradiatied with highly charged ions

Author

Cervera, S, primary, Trassinelli, M, additional, Marangolo, M, additional, Carlsson, L Bernard, additional, Eddrief, M, additional, Etgens, V H, additional, Gafton, V, additional, Hidki, S, additional, Lamour, E, additional, Lévy, A, additional, Macé, S, additional, Prigent, C, additional, Rozet, J-P, additional, Steydli, S, additional, Zheng, Y, additional, and Vernhet, D, additional

Published
2015
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36. Impacts of highly charged ions as seeds in a magneto-structural phase transition of magnetocaloric thin films

Author

Cervera, S, primary, Trassinelli, M, additional, Marangolo, M, additional, Bernard-Carlsson, L, additional, Eddrief, M, additional, Etgens, V H, additional, Gafton, V, additional, Hidki, S, additional, Lacaze, E, additional, Lamour, E, additional, Prigent, C, additional, Rozet, J-P, additional, Steydli, S, additional, Zheng, Y, additional, and Vernhet, D, additional

Published
2015
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39. Primary processes: from atoms to diatomic molecules and clusters

Author

Fléchard, X, primary, Adoui, L, additional, Ban, G, additional, Boduch, P, additional, Cassimi, A, additional, Chesnel, J Y, additional, Durand, D, additional, Frémont, F, additional, Guillous, S, additional, Grandin, J P, additional, Hennecart, D, additional, Jacquet, E, additional, Jardin, P, additional, Lamour, E, additional, Liénard, E, additional, Lelièvre, D, additional, Maunoury, L, additional, Méry, A, additional, Naviliat-Cuncic, O, additional, Prigent, C, additional, Ramillon, J M, additional, Rangama, J, additional, Rozet, J P, additional, Steydli, S, additional, Trassinelli, M, additional, and Vernhet, D, additional

Published
2015
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50. Charge Equilibrium of a Laser-Generated Carbon-Ion Beam in Warm Dense Matter

Author

Gauthier, M., primary, Chen, S. N., additional, Levy, A., additional, Audebert, P., additional, Blancard, C., additional, Ceccotti, T., additional, Cerchez, M., additional, Doria, D., additional, Floquet, V., additional, Lamour, E., additional, Peth, C., additional, Romagnani, L., additional, Rozet, J.-P., additional, Scheinder, M., additional, Shepherd, R., additional, Toncian, T., additional, Vernhet, D., additional, Willi, O., additional, Borghesi, M., additional, Faussurier, G., additional, and Fuchs, J., additional

Published
2013
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