Publications

2004

• Geometrical barriers and lower critical field in MgB2 single crystals
  
  • Lyard L.
  • Klein Thierry
  • Marcus J.
  • Brusetti R.
  • Marcenat C.
  • Konczykowski M.
  • Mosser V.
  • Kim K.H.
  • Kang B.W.
  • Lee H.S.
  • Lee S.I.
  Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 2004, 70, pp.180504(R). The first penetration field sHpd has been deduced from local magnetization and specific heat measurements in magnesium diboride single crystals. For Ha ic, the geometrical barriers (GB) play a dominant role in the irreversibility mechanism. In thin samples, neglecting the GB in this direction would then lead to a large overestimation of Hc1 deduced from Hp through the standard elliptical formula. The lower critical field is found to be isotropic at low temperature (0.11±0.01 T). (10.1103/PhysRevB.70.180504)
  DOI : 10.1103/PhysRevB.70.180504
• A Raman and MAS NMR study of mixed alkali Na-K and Na-Li aluminoborosilicate glasses
  
  • Ollier Nadège
  • Charpentier Thibault
  • Boizot Bruno
  • Wallez G.
  • Ghaleb D.
  Journal of Non-Crystalline Solids, Elsevier, 2004, 341 (1-3), pp.26-34. (10.1016/j.jnoncrysol.2004.05.010)
  DOI : 10.1016/j.jnoncrysol.2004.05.010
• Chip based on In-situ Synthesis Technology utilizing Polymer as a Masking Material
  
  • Kuroiwa T.
  • Vinet F.
  • Vauchier C.
  • Yasuhiro G.
  • Ishikawa N.
  • Obara D.
  • Soucemarianadin Arthur
  , 2004, pp.pas précise.
• β irradiation in borosilicate glasses: the role of the mixed alkali effect
  
  • Ollier N.
  • Boizot B.
  • Reynard Bruno
  • Ghaleb D.
  • Petite G.
  Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Elsevier, 2004, 218, pp.176-182. Two series of mixed alkali borosilicate glasses have been studied (Na/K and Na/Li) in order to examine the mixed alkali effect influence on the structure evolution of β-irradiated glasses. In both glass series, paramagnetic defects concentration shows a non-linear variation with Na content. The defect nature is also affected and more particularly boron oxygen hole center versus oxygen hole center relative proportion. By Raman spectroscopy, we showed that polymerization increase and molecular oxygen production, linked to the alkali migration, were minimized for some irradiated glass compositions. Mixed alkali effect blocks structural changes under electron irradiation in Na/Li glasses while for Na/K glasses, structural evolutions are smaller than in pure alkali glasses but non-completely annihilated. (10.1016/j.nimb.2003.12.014)
  DOI : 10.1016/j.nimb.2003.12.014
• He migration in implanted UO2 sintered disks
  
  • Guilbert Severine
  • Sauvage Thierry
  • Garcia Philippe
  • Carlot Gaelle
  • Barthe Marie-France
  • Desgardin Pierre
  • Blondiaux Gilbert
  • Corbel Catherine
  • Piron Jean-Paul
  • Gras Jean-Marie
  Journal of Nuclear Materials, Elsevier, 2004, 327 (2-3), pp.88-96. The behaviour of helium implanted in sintered uranium dioxide disks has been investigated as a function of annealing temperature. UO2 disks have been implanted with 1 MeV 3He ions at a fluence of 1 × 1016 3He cm−2 using a Van der Graaff accelerator. These implantation conditions lead to a local helium concentration of 0.2 at.% at a depth of 1.9 μm in UO2. The 3He(d,α)1H Nuclear Reaction Analysis method was used to determine the helium depth profile after the various annealing stages. The experimental results measured after 1100 °C anneal were analysed using a simple model which satisfactorily reproduces the observed helium depth profile changes. The intragranular helium diffusion coefficient is estimated and the result is assessed against other data published in the open literature. (10.1016/j.jnucmat.2004.01.024)
  DOI : 10.1016/j.jnucmat.2004.01.024
• Profile measurements of helium implanted in UO2 sintered pellets by using the 3He(d,α)1H nuclear reaction analysis technique
  
  • Sauvage Thierry
  • Erramli Hassan
  • Guilbert Severine
  • Vincent Laetitia
  • Barthe Marie-France
  • Desgardin Pierre
  • Blondiaux Gilbert
  • Corbel Catherine
  • Piron Jean-Paul
  • Labohm F.
  • van Veen A.
  Journal of Nuclear Materials, Elsevier, 2004, 327 (2-3), pp.159-164. (10.1016/j.jnucmat.2004.02.002)
  DOI : 10.1016/j.jnucmat.2004.02.002
• Direct Transition from Bose Glass to Normal State in the (K,Ba)BiO3 Superconductor
  
  • Klein Thierry
  • Marcenat C.
  • Blanchard S.
  • Marcus J.
  • Bourbonnais C.
  • Brusetti R.
  • J. van Der Beek C.
  • Konczykowski M.
  Physical Review Letters, American Physical Society, 2004, 92, pp.037005. The introduction of columnar defects in K; Ba BiO3 single crystals shifts both the irreversibility and thermodynamic transition lines, respectively, deduced from ac susceptibility (and/or transport) and specific heat measurements, upwards. This shift can be attributed to the defect-induced decrease of the difference ( F) between the free energies in the superconducting and the normal states, assuming that the position of the superconducting transition is given by the condition j Fj kBT= 3. This criterion also perfectly reproduces the influence of the angle between the tracks and the external field. This result suggests that no vortex liquid phase exists in this system. (10.1103/PhysRevLett.92.037005)
  DOI : 10.1103/PhysRevLett.92.037005
• Transfer of magnetization by spin injection between both interfaces of a Ni nanowire
  
  • Wegrowe J. -E.
  • Dubey M.
  • Wade T.
  • Drouhin H. -J.
  • Konczykowski M.
  Journal of Applied Physics, American Institute of Physics, 2004, 96, pp.4490-4493. Magnetization switching provoked by spin-injection is studied in Ni nanowires of various size and morphology. The response of the magnetization to the spin-injection is studied as a function of the amplitude of the current, the temperature, and the symmetry of the interfaces. The amplitude of the response of the magnetization to spin-injection is a decreasing function of the temperature, does not depend on the current sign, and occurs only in the case of asymmetric interfaces. It is shown that the spin-injection does not act on small magnetic inhomogeneities inside the layer. Some consequences in terms of longitudinal spin-transfer are discussed.
• Alfred Wilm and the beginnings of Duralumin
  
  • Hardouin Duparc Olivier
  Revue de Métallurgie, EDP Sciences, 2004, n° 5, pp.353-360. The discovery of Duralumin took place in a military context. The Prussian engineer Alfred Wilm had been mandated in Neubabelsberg near Berlin to develop such an improved alloy, the name of which is as much due to the fact that it is hard as to the fact it has first been industrially produced in Düren. International cooperations as well as harsh competitions have accompanied the first researches on this alloy in the beginning of the twentieth century
• Study of excimer laser irradiation effects on properties of crystalline YBaCuO thin films
  
  • Abal'Oshev A.
  • Abal'Osheva I.
  • J. Lewandowski S.
  • J. van Der Beek C.
  • Konczykowski M.
  • Rizza G.
  • Barbanera S.
  Acta Physica Polonica A, Polish Academy of Sciences. Institute of Physics, 2004, 106, pp.681. The influence of UV laser irradiation on the physical properties of epitaxial YBa2CU3O7-delta thin (< 1 mum) films fabricated by laser ablation was studied. The samples were irradiated by pulsed excimer laser beam at different incident energy densities E-ir less than or equal to 130 mJ/cm(2), i.e. 2-3 times below the ablation threshold of YBaCuO. The analysis of the sample cross-section using transmission electron microscope shows that such irradiation forms a disordered layer on the top of the crystalline film. Sample surface amorphization was observed also by atomic force microscope. Due to strong UV irradiation absorption in YBaCuO this surface layer acts like a protective cover for the sample interior. Only a small reduction of superconducting critical temperature T-c was observed. Both transport measurements in normal state and magneto-optical studies in superconducting state indicate that between the disordered layer and the bottom non-modified part of the film there exists a wide transitional region with reduced carrier concentration
• beta irradiation borosilicate glasses: the role of the mixed alkali effect
  
  • Ollier N.
  • Boizot B.
  • Reynard B.
  • Ghaleb D.
  • Petite G.
  Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Elsevier, 2004, 218, pp.176. We investigate the photoemission for a set of wide band-gap crystals irradiated by femtosecond Ti-Sapphire laser pulses at intensities varying from 0.5 to 6 TW/cm(2) (below the optical breakdown threshold). The measured total electron yield increases linearly with the laser intensity in this intensity range. An intense and wide plateau of high energy electrons appears in the photoelectron spectra at excitation intensities larger than 1 TW/cm(2). The exponential cut-off of this plateau reaches 40 eV at maximal applied intensities. In order to explain such a behavior, we propose a mechanism where the heating is due to a sequence of direct interbranch one- and multi-photon transitions in the conduction band
• Tailoring bulk and surface grafting of poly(acrylic acid) in electron-irradiated PVDF
  
  • Clochard Marie-Claude
  • Bègue J
  • Lafon A
  • Caldemaison D
  • Bittencourt C
  • Pireaux J.-J
  • Betz N
  Polymer, Elsevier, 2004, 45, pp.8683. Endowing conventional hydrophobic poly(vinylidene fluoride) (PVDF) films with hydrophilic properties was conducted using electron beam irradiation. Grafting of acrylic acid (AA) in/onto pre-irradiated PVDF films was investigated. Reaction parameters, monomer concentration and inhibitor concentration were examined. Radiation grafted films (PVDF-g-PAA) were synthesized with various grafting yields ranging from 12 to 130 wt % in presence of Mohr's salt (25 wt %). Below 80 wt % of monomer concentration, the degree of swelling was found to increase with the grafting yield. The PAA was arranged randomly in all PVDF matrix (grafting through). Above 80 wt % of monomer concentration, the PAA was grafted only onto the surface of PVDF films leading to a highly dense layer of PAA. Grafting through or surface grafting processes were achieved by varying the water fraction in the initial monomer solution. Water molecule acts not only as a carrier for the monomer but also as a plasticizer expanding the film in the three dimensions. Evidences of grafting through and surface grafting were produced using FTIR in ATR mode, SEM coupled to X-ray detection and XPS. An accurate quantification of AA units was possible up to the micromole via a Cu 2C –EDTA complex analyzed by UV–vis spectroscopy. q (10.1016/j.polymer.2004.10.052)
  DOI : 10.1016/j.polymer.2004.10.052
• Electronic structure and electron energy-loss spectroscopy of ZrO2 zirconia
  
  • K. Dash L.
  • Vast N.
  • Baranek P.
  • C. Cheynet M.
  • Reining L.
  Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 2004, 70, pp.245116. The atomic and electronic structures of zirconia are calculated within density functional theory, and their evolution is analyzed as the crystal-field symmetry changes from tetrahedral [cubic (c-ZrO2) and tetragonal (t-ZrO2) phases] to octahedral (hypothetical rutile ZrO2), to a mixing of these symmetries (monoclinic phase, m-ZrO2). We find that the theoretical bulk modulus in c-ZrO2 is 30% larger than the experimental value, showing that the introduction of yttria in zirconia has a significant effect. Electronic structure fingerprints which characterize each phase from their electronic spectra are identified. We have carried out electron energy-loss spectroscopy experiments at low momentum transfer and compared these results to the theoretical spectra calculated within the random phase approximation. We show a dependence of the valence and 4p (N2,3 edge) plasmons on the crystal structure, the dependence of the latter being brought into the spectra by local-field effects. Last, we attribute low energy excitations observed in EELS of m-ZrO2 to defect states 2 eV above the top of the intrinsic valence band, and the EELS fundamental band gap value is reconciled with the 5.2 or 5.8 eV gaps determined by vacuum ultraviolet spectroscopy
• Superconducting pinning by magnetic domains in a ferromagnet-superconductor bilayer
  
  • Z. Cieplak M.
  • Adamus Z.
  • Konczykowski M.
  • M. Chen X.
  • Byczuk A.
  • Abal'Oshev A.
  • Sang H.
  • L. Chien C.
  Acta Physica Polonica A, Polish Academy of Sciences. Institute of Physics, 2004, 106, pp.693. The local flux profile and the critical current are studied using an array of Hall sensors in a ferromagnetic-superconducting bilayer which consists of niobium film covering ferromagnetic Co/Pt multilayer with perpendicular magnetic anisotropy. The results indicate about threefold enhancement of the flux pinning in niobium layer caused by the isolated magnetic domains which are created during the magnetization reversal of the Co/Pt multilayer. The geometrical barrier is absent, and the critical current is strongly peaked in close vicinity to the sample center, suggesting that the critical state differs from that predicted by the Bean model
• Amorphous vortex phase in Bi2Sr2CaCu2O8 after the first order liquid-solid phase transition
  
  • Menghini M.
  • Fasano Y.
  • de La Cruz F.
  • Banerjee S.S.
  • Myasoedov Y.
  • Zeldov E.
  • J. van Der Beek C.
  • Konczykowski M.
  • Tamegai T.
  Journal of Low Temperature Physics, Springer Verlag (Germany), 2004, 135, pp.139. It is widely accepted that the first-order vortex liquid-solid phase transition is associated with a crystalline solid phase and the second order transition with an amorphous one. The combination of a technique that determines the order of the transition with the visualization of the vortex structure has allowed the detection, for the first time, of a first-order liquid-solid transition without structural symmetry change. The results show that the quasi-long range order of the solid phase is not a necessary condition for the first-order phase transition to occur. This opens an important question on the microscopic origin of the liquid-solid phase transition in vortex matter
• Persistence of the intrinsic transition in the vortex matter of disordered BSCCO:2212 crystals
  
  • Konczykowski M.
  • J. van Der Beek C.
  • Zeldov E.
  • Ming Li.
  • H. Kes P.
  Physica C: Superconductivity and its Applications, Elsevier, 2004, 408, pp.547. The first order melting transition (FOT) in vortex matter of clean Bi2Sr2CaCu2O8 crystals, is identified by a discontinuity in the reversible magnetization, which extends to the low temperature (irreversible) regime in the form of a jump in the energy barrier vs. current, U(J), variation. Heavy ion irradiation disorders the vortex lattice, enhances flux pinning, and is believed to suppress the FOT. However, in underdoped samples, detailed measurements of magnetic relaxation by the Hall-array technique reveal the existence of a discontinuous jump in the U(J) curve precisely at the location of FOT of pristine crystals
• Potentialities of GaN-based microcavities in strong coupling regime at room temperature.
  
  • Ollier N.
  • Natali F.
  • Byrne D.
  • Disseix Pierre
  • Vasson A.
  • Leymarie Joël
  • Semond F.
  • Massies J.
  Superlattices and Microstructures, Elsevier, 2004, 34 (4-6), pp.599-606. In a recent publication [N. Antoine-Vincent, F. Natali, D. Byrne, A. Vasson, P. Disseix, J. Leymarie, M. Leroux, F. Semond, J. Massies, Phys. Rev. B 68 (2003) 153313], we have highlighted for the first time the exciton–photon strong coupling in a GaN-based microcavity and obtained a Rabi splitting of 31 meV persistent at 77 K. Our aim is now to study the feasibility of GaN-based microcavities for which the strong coupling regime would be maintained at room temperature. A complex heterostructure containing GaN/AlGaN quantum wells (QWs) is investigated by photoreflectivity and reflectivity at 5 K. The QW thickness is 3 nm and the Al composition and thickness of the barriers are respectively 0.11 and 10 nm. From the modeling of the experimental spectra, the values of the oscillator strength, the energy and the broadening parameter of the QW fundamental transition are determined; the broadening is found to be relatively weak (15 meV). Simulations of microcavities containing QWs have then been performed including this set of parameters: a theoretical Rabi splitting of 34 meV is obtained at 5 K. Considering an additional broadening induced by the increase of the temperature (23 meV), the strong coupling regime could be maintained theoretically at room temperature in such a structure. This is due to the low value of the inhomogeneous broadening related to the QW transition which is lower than in bulk GaN. The influence of the QW number and the nature of the Bragg mirror on the Rabi splitting is then discussed in realistic structures. (10.1016/j.spmi.2004.09.017)
  DOI : 10.1016/j.spmi.2004.09.017
• Photoconductivity and photoemission studies of diamond irradiated by ultrashort VUV pulses
  
  • Gaudin Jérôme
  • Geoffroy Ghita
  • Guizard Stéphane
  • Petite Guillaume
  • Klimentov Serguei M.
  • Garnov Serguei V.
  • Pivovarov Pavel A.
  • Carre Bertrand
  • Belsky Andrei
  • Martin Patrick
  Applied Physics B - Laser and Optics, Springer Verlag, 2004, 78, pp.1001.
• SPATIALLY PERIODIC STRUCTURES, UNDER FEMTOSECOND PULSED EXCITATION OF CRYSTALS
  
  • Petite Guillaume
  • Martynovitch Evgueni F.
  • Dresvianski Vladimir P.
  • Starchenko Anton A.
  Applied Physics Letters, American Institute of Physics, 2004, 84, pp.4550. Measuring the luminescence intensity of specially prepared irradiation defects induced in crystals, we observe that the longitudinal structure of quasi-interferences induced by two orthogonally polarized femtosecond pulses propagating together with different velocities is insensitive to the spatial broadening due to velocity dispersion in the crystals. On the contrary, it does depend on the pulse duration when it is changed by varying the spectral width of the radiation. It thus allows a direct measurement of the coherence time of such pulses. Stability of the axial selectivity is a good sign, taking away a number of serious limitations concerning possible applications.
• Vortex Phase Diagram in Bi2Sr2CaCu2O8+$\delta$ with Damage Tracks Created by 30 MeV Fullerene Irradiation
  
  • Ishikawa N.
  • van der Beek C. J.
  • Dunlop A.
  • Jaskierowicz G.
  • Li Ming
  • Kes P. H.
  • Della-Negra S.
  Journal of the Physical Society of Japan, Physical Society of Japan &#26085;&#26412;&#29289;&#29702;&#23398;&#20250;, 2004, 73, pp.2813-2821. Using 30 MeV C60 fullerene irradiation, we have produced latent tracks of diameter 20 nm and length 200 nm, near the surface of single crystalline Bi2Sr2CaCu2O8+δ. A preliminary transmission electron microscopy study shows evidence for a very high density of deposited energy, and the ejection of material from the track core in very thin specimens. The latent tracks reveal themselves to be exceptionally strong pinning centers for vortices in the superconducting mixed state. Both the critical current density and magnetic irreversibility line are significantly enhanced. The irradiated crystals present salient features of the (B,T) phase diagram of vortex matter both of pristine crystals, such as the first order vortex phase transition, and the exponential Bose-glass line characteristic of heavy ion-irradiated crystals. We show that the latter is manifestly independent of the pinning potential (10.1143/JPSJ.73.2813)
  DOI : 10.1143/JPSJ.73.2813
• b-irradiation in borosilicate glasses : the role of the mixed alkali effect
  
  • Ollier Nadège
  • Boizot Bruno
  • Reynard Bruno
  • Ghaleb Dominique
  • Petite Guillaume
  Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Elsevier, 2004, 218, pp.176-182.
• Porous vortex matter
  
  • Banerjee S.S.
  • Zeldov E.
  • Soibel A.
  • Myasoedov Y.
  • Rappaport M.
  • Menghini M.
  • Fasano Y.
  • de La Cruz F.
  • J. van Der Beek C.
  • Konczykowski M.
  • Tamegai T.
  Physica C: Superconductivity and its Applications, Elsevier, 2004, 408, pp.495. Structure, dynamics, and thermodynamic properties of vortex matter in the presence of a low density of columnar defects (CDs) were studied in BSCCO crystals. Magnetic decorations show that when vortices outnumber CDs a heterogeneous vortex matter is formed consisting of two populations of vortices: vortices residing on CDs form a matrix of pinned vortices, whereas the interstitial vortices form ordered crystallites within the 'pores' of the matrix. Differential magneto-optical studies reveal that at elevated fields this porous phase melts in two stages, a first-order melting of the crystallites at a temperature considerably higher than the pristine melting, and a continuous melting of the matrix at still higher temperature. At low fields the two transitions occur simultaneously, giving rise to a sharp kink in the observed melting line
• Neural correlates of implicit object identification.
  
  • Pins D.
  • Meyer M. E.
  • Foucher J.
  • Humphreys G.
  • Boucart M.
  Neuropsychologia, Elsevier, 2004, 42 (9), pp.1247-59. The present study sought to assess neural correlates of implicit identification of objects by means of fMRI, using tasks that require matching of the physical properties of objects. Behavioural data suggests that there is automatic access to object identity when observers attend to a physical property of the form of an object (e.g. the object's orientation) and no evidence for semantic processing when subjects attend to colour. We evaluated whether, in addition to neural areas associated with decisions to specific perceptual properties, areas associated with access to semantic information were activated when tasks demanded processing of the global configuration of pictures. We used two perceptual matching tasks based on the global orientation or on the colour of line drawings. Our results confirmed behavioural data. Activations in the inferior occipital cortex, fusiform and inferior temporal gyri in both tasks (orientation and colour) account for perceptual and structural processing involved in each task. In contrast, activations in the posterior and medial parts of the fusiform gyrus, shown to be involved in explicit semantic judgements, were more pronounced in the orientation-matching task, suggesting that semantic information from the pictures is processed in an implicit way even when not required by the task. Thus, this study suggests that cortical regions usually involved in explicit semantic processing are also activated when implicit processing of objects occurs. (10.1016/j.neuropsychologia.2004.01.005)
  DOI : 10.1016/j.neuropsychologia.2004.01.005
• Local crystallization induced in Fe-based amorphous alloys by swift heavy projectiles
  
  • Rizza G.
  • Dunlop A.
  • Jaskierowicz G.
  • Kopcewicz M.
  Nuclear Instruments and Methods in Physics Research, North-Holland ; Elsevier [1981-1984], 2004, 226, pp.609-621. We report the effect of the high density of electronic excitation deposited along the path of swift heavy ions in various amorphous alloys. The samples were irradiated at low temperature with GeV Pb ions up to fluences of 1 × 1011 to 2.3 × 1013 cm−2. The formation of nanocrystalline phases was observed by transmission electron microscopy in the FINEMET-like Fe73.5Nb4.5Cr5Cu1B16 alloy and in the NANOPERM ternary Fe90Zr7B3 glassy systems but not in the Fe80.5Nb7B12.5 alloy. The crystallization phenomenon was interpreted in terms of the relaxation of the high level of energy deposited in electronic excitations along the path of Pb ions in the target, which induce radial pressure waves in the vicinity of the projectile trajectories. These mechanical stresses destabilize the amorphous structure and induce nanocrystallization
• Raman investigation of structural changes induced by e-beam irradiation in Ge doped silica MCVD glasses
  
  • S. Jacqueline A.
  • Poumellec B.
  • C. Chervin J.
  • Garcia-Blanco S.
  • Esnouf S.
  Materials Science and Engineering: B, Elsevier, 2004, 107, pp.46. Microstructural changes of germanium (Ge)-doped silica glasses irradiated with electron beam (e-beam) have been investigated by Raman spectroscopy. Two mechanisms correlated to the specific volume changes induced by e-beam irradiation were observed by surface topography measurement. As we have previously demonstrated, they depend on the Ge content and the irradiation dose. The compaction of the structure (which decreases with the Ge concentration) is attributed to an increase of the three and four-membered ring species which is maximal at the surface and decreases with depth. By means of Monte-Carlo simulations, we have correlated the energy deposition with the compaction process. Some specific Raman components are attributed to the expansion of the structure observed for high Ge content and high irradiation dose. In this case, an increase of the anti-symmetric stretching modes of the bridging oxygen in the Si---O---Ge and Si---O---Si groups are observed at the surface