Publications

2004

• Optical anisotropy induced by cesium adsorption on the As-rich c(2X8) reconstruction of GaAs(001)
  
  • Hogan C.
  • Paget D.
  • E. Tereshchenko O.
  • Reining L.
  • Onida G.
  Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 2004, 6912, pp.5332. Upon adsorption of Cs, the As-rich c(2 X 8)/(2 X 4) reconstruction of GaAs(001) is found to exhibit an intense negative signal between 3 eV and 5 eV in the reflectance anisotropy spectrum. This signal has a universal character in that similar features also appear on the Ga-rich surface. The mechanism of this signal is interpreted using ab initio calculations of Cs adsorption at As and Ga sites of the As-rich surface. The calculations succeed in explaining the universality of the signal. In the vicinity of the E-0' bulk critical point at 4.5 eV, the signal arises from perturbation of bulk states terminating at the surface. At lower energies, the signal arises from the creation of new surface resonances induced by the Cs adatom
• Observation of high energy photoelectrons from solids at moderate laser intensity
  
  • N. Belsky A.
  • Bachau H.
  • Gaudin J.
  • Geoffroy G.
  • Guizard S.
  • Martin P.
  • Petite G.
  • Philippov A.
  • Vasil'Ev A.N.
  • N. Yatsenko B.
  Applied Physics B - Laser and Optics, Springer Verlag, 2004, 78, pp.989. 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
• 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
• beta irradiation borosilicate glasses: the role of the mixed alkali effect
  
  • Lyard L.
  • Klein T.
  • Marcus J.
  • Brusetti R.
  • Marcenat C.
  • Konczykowski M.
  • Mosser V.
  • H. Kim K.
  • W. Kang B.
  • S. Lee H.
  • I. Lee S.
  Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Elsevier, 2004, 218, pp.176. The first penetration field (H-p) has been deduced from local magnetization and specific heat measurements in magnesium diboride single crystals. For H-a(parallel toc), 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 H-c1 deduced from H-p through the standard elliptical formula. The lower critical field is found to be isotropic at low temperature (similar to0.11+/-0.01 T).
• 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
• Electron acceleration by surface plasma waves in the interaction between femtosecond laser pulses and sharp-edged overdense plasmas
  
  • Kupersztych J
  • Raynaud M
  • Riconda C
  Physics of Plasmas, American Institute of Physics, 2004. The relativistic acceleration of electrons by the field of surface plasma waves created in the interaction between ultrashort high-intensity laser pulses with sharp-edged overdense plasmas has been investigated. It is shown that the initial phase of the wave experienced by the electrons play a leading part by yielding a well-defined peaked structure in the energy distribution function. This study suggests that resonant excitation of surface plasma waves could result in quasi-monokinetic energetic electron bunches. When the space charge field becomes too strong, this mechanism can evolve toward a true absorption process of the surface wave energy via an enhanced ''vacuum heating'' mechanism generalized to the case of surface plasma waves. (10.1063/1.1650353͔)
  DOI : 10.1063/1.1650353͔