Now showing items 1-11 of 11

    • Antiparallel interface coupling evidenced by negative rotatable anisotropy in IrMn/NiFe bilayers 

      Schäfer, Deise; Grande, Pedro Luis; Pereira, Luis Gustavo; Azevedo, Gustavo de Medeiros; Oliveira, Artur Harres de; Sousa, Marcos Antonio de; Pelegrini, Fernando; Geshev, Julian Penkov (2015) [Journal article]
      Negative rotatable anisotropy is estimated via ferromagnetic resonance measurements in as-made, annealed, and ion-irradiated IrMn3/Ni81Fe19 bilayers. Opposite to previous observations, inverse correlation between rotatable ...
    • Co-cubstitution effects on the Fe valence in the BaFe2As2 superconducting compound : a study of hard x-ray absorption spectroscopy 

      Bittar, Eduardo Matzenbacher; Adriano, C.; Garitezi, T. M.; Rosa, P. F. S.; Ferreira, Leticie Mendonca; Garcia, Flávio; Azevedo, Gustavo de Medeiros; Pagliuso, P. G. (2011) [Journal article]
      The Fe K x-ray absorption near edge structure of BaFe₂-xCoxAs₂ superconductors was investigated. No appreciable alteration in shape or energy position of this edge was observed with Co substitution. This result provides ...
    • Giant Barkas effect observed for light ions channeling in Si 

      Azevedo, Gustavo de Medeiros; Grande, Pedro Luis; Behar, Moni; Dias, Johnny Ferraz; Schiwietz, Gregor (2001) [Journal article]
      Measurements of the electronic energy loss are presented for ⁴He and ⁷Li ions channeling along the Si main axial directions at intermediate to high projectile energies. The Barkas effect, an energy-loss enhancement ...
    • High temperature emissivity, reflectivity, and x-ray absorption of BiFeO3 

      Massa, Néstor E.; Del Campo, Leire; Meneses, Domingos de Souza; Echegut, Patrick; Fabbris, Gilberto Fernandes Lopes; Azevedo, Gustavo de Medeiros; Martínez Lope, María Jesús; Alonso, José Antônio (2010) [Journal article]
      We report on the lattice evolution of BiFeO3 as function of temperature using far infrared emissivity, reflectivity, and x-ray absorption local structure. A power law fit to the lowest frequency soft phonon in the magnetic ...
    • In-situ transmission electron microscopy growth of nanoparticles under extreme conditions 

      Luce, Flavia Piegas; Oliviero, Erwan Marie Hubert; Azevedo, Gustavo de Medeiros; Baptista, Daniel Lorscheitter; Fichtner, Paulo Fernando Papaleo (2016) [Journal article]
      The formation and time resolved behavior of individual Pb nanoparticles embedded in silica have been studied by in-situ transmission electron microscopy observations at high temperatures (400–1100 C) and under 200 keV ...
    • Investigation of indirect structural and chemical parameters of GeSi nanoparticles in a silica matrix by combined synchrotron radiation techniques 

      Gasperini, A. A. M.; Malachias, A.; Fabbris, Gilberto Fernandes Lopes; Kellermann, Guinter; Gobbi, Angelo Luiz; Avendaño Soto, E.; Azevedo, Gustavo de Medeiros (2012) [Journal article]
      The formation of GeSi nanoparticles on an SiO2 matrix is studied here by synchrotron-based techniques. The shape, average diameter and size dispersion were obtained from grazing-incidence small-angle X-ray scattering data. ...
    • Negative rotatable anisotropy in IrMn/Cr/Co thin films 

      Nicolodi, Sabrina; Pereira, Luis Gustavo; Oliveira, Artur Harres de; Azevedo, Gustavo de Medeiros; Schmidt, Joao Edgar; García Aguilar, I.; Souza Neto, N. M.; Deranlot, Cyrile; Petroff, Frédéric; Geshev, Julian Penkov (2012) [Journal article]
      This work presents modifications of the magnetic properties of polycrystalline IrMn/Cr(tCr)/Co films where the Cr spacer thickness tCr was varied between 0.25 and 3 nm. High-resolution transmission electron microscopy, ...
    • New approach for structural characterization of planar sets of nanoparticles embedded into a solid matrix 

      Sanchez, Dario Ferreira; Marmitt, Gabriel Guterres; Marin, Cristiane; Baptista, Daniel Lorscheitter; Azevedo, Gustavo de Medeiros; Grande, Pedro Luis; Fichtner, Paulo Fernando Papaleo (2013) [Journal article]
      In this work we demonstrate that Medium Energy Ion Scattering (MEIS) measurements in combination with Transmission Electron Microscopy (TEM) or Grazing Incidence Small Angle X-Ray Scattering (GISAXS) can provide a complete ...
    • Pressure and chemical substitution effects in the local atomic structure of BaFe2As2 

      Granado, E.; Ferreira, Leticie Mendonca; Garcia, Flávio; Azevedo, Gustavo de Medeiros; Fabbris, Gilberto Fernandes Lopes; Bittar, Eduardo Matzenbacher; Adriano, C.; Garitezi, T. M.; Rosa, P. F. S.; Bufaiçal, L. F.; Avila, M. A.; Terashita, H.; Pagliuso, P. G. (2011) [Journal article]
      The effects of K and Co substitutions and quasihydrostatic applied pressure (P < 9 GPa) in the local atomic structure of BaFe2As2, Ba(Fe0.937Co0.063)2As2 and Ba0.85K0.15Fe2As2 superconductors were investigated by extended ...
    • Random and channeling stopping powers of He and Li ions in Si 

      Azevedo, Gustavo de Medeiros; Behar, Moni; Dias, Johnny Ferraz; Grande, Pedro Luis; Silva, Douglas Langie da; Schiwietz, Gregor (2002) [Journal article]
      In this work we have measured the electronic stopping powers of ⁴He and ⁷Li ions for channeling and random directions in Si as a function of the incident ion energy. The channeling (‹100› for Li, ‹110› and ‹111› for Li and ...
    • Range study of Eu implanted into Si channeling directions : evidence for the Z/sub 1/ effect 

      Azevedo, Gustavo de Medeiros; Behar, Moni; Grande, Pedro Luis; Borges Jr., Itamar (2001) [Journal article]
      Eu ions have been implanted along the Si ‹100›, ‹111›, and ‹110› directions at 623 K with energies ranging from 15 keV to 50 keV. The depth profiles have been measured using Rutherford backscattering spectroscopy (RBS). A ...