Publications

2004

• Spin-dependent thermopower in Co/Cu multilayer nanowires
  
  • Gravier L.
  • Fabian A.
  • Rudolf A.
  • Cachin A.
  • E. Wegrowe J.
  • P. Ansermet J.
  Journal of Magnetism and Magnetic Materials, Elsevier, 2004, 271, pp.153. The magnetic field dependence of the thermoelectrical power of a series of Co/Cu multilayered nanowires grown by electrodeposition in a polymer matrix is almost that predicted by the Mott formula in the temperature range of 15300 K. Application of the two-current model to thermopower yields (S-up arrow - S-down arrow)/(S-up arrow + S-down arrow) the relative difference between the thermopower of each spin channel
• Swift heavy ion induced graft polymerization in track etched membranes' submicroscopic pores
  
  • Mazzei R.
  • García Bermúdez G.
  • Betz N.
  • Cabanillas E.
  Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Elsevier, 2004, 226, pp.575. Cl or Pb irradiated foils of poly(vinylidene fluoride) (PVDF) were chemically etched to produce nuclear track membranes (NTM) with submicroscopic pores. The NTM were grafted with styrene using the remaining active sites produced by the heavy ion beams. Experimental curves of grafting yield were measured by weight difference as a function of ion fluence and etching time. As the etching time was increased from 0 to 30 min a decrease of the grafting yield was observed. Grafted foils were also analysed by Fourier transform infrared spectroscopy (FTIR). Both measurements suggest that the styrene was grafted on the pore wall of the NTM using the active sites left by the ion beam
• Superconductivity from doping Boron icosahedra.
  
  • Calandra Matteo
  • Vast Nathalie
  • Mauri Francesco
  Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 2004, 69, pp.224505. We propose an alternative route to achieve the superconducting state in boron-rich solids, the hole doping of B12 icosahedra. For this purpose we consider a prototype metallic phase of B13C2. We show that in this compound the boron icosahedral units are mainly responsible for the large phonon frequencies logarithmic average, 65.8 meV, and the moderate electron-phonon coupling lambda= 0.81. We suggest that this high Tc could be a general feature of hole-doped boron icosahedral solids. Moreover our calculated moderate value of lambda excludes the formation of bipolarons localized on the icosahedral length scale as suggested by previous authors. (10.1103/PhysRevB.69.224505)
  DOI : 10.1103/PhysRevB.69.224505
• Track formation in fluorapatite irradiated with energetic cluster ions
  
  • Jaskierowicz G.
  • Dunlop A.
  • Jonckheere R.
  Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Elsevier, 2004, 222, pp.213. We present preliminary transmission electron microscopy observations on apatite samples irradiated at 300 K with 30 MeV C60 cluster ions up to fluences ranging from 1 × 1010 to 3 × 1011 cm-2. Each incoming projectile generates strong structural modifications in the vicinity of its path as a consequence of the very high density of energy deposited in electronic processes. It will be shown that a wide variety of morphologies is found in neighbouring tracks, some of them appearing as "continuous", whereas in the same sample region many consist of one or several alignments of droplets, which could be either voids or gas filled bubbles. Electron diffraction patterns seem to indicate that the core of the track do not consist of amorphous solid matter. The tracks induced under cluster irradiation evolve under the beam in the electron microscope. Some faceting of the damaged regions appears as the discontinuity along the track length increases
• Comment on "Molecular dynamics study of the threshold displacement energy in vanadium
  
  • Vajda P.
  , 2004. The simulation study on Frenkel pair creation in vanadium by L.A. Zepeda-Ruiz et al. (Phys. Rev. B 67, 134114, 2003) is criticized for its lack of reference to existing experimental work and for generally inadequate treatment of literature data. Hence, the validity of the ensuing discussion of various results (e.g. the value of the minimum TDE and the Frenkel pair stability in V) is questioned.
• Spatially periodical structures, under femtosecond pulsed excitation of irradiated AI203 crystals
  
  • F. Martynovitch E.
  • Petite G.
  • P. Dresvianski V.
  • A. Starchenko 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