Browsing Exact and Earth Sciences by Author "Azevedo, Gustavo de Medeiros"

Now showing items 1-14 of 14

    • 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. ...

    • A luz sincrotron iluminando a formação de professores 

      Acioly, Vitor; Picoreti, Renan; Rocha, Tulio Costa Rizuti da; Azevedo, Gustavo de Medeiros; Santos, Antônio Carlos Fontes dos (2020) [Journal article]
      Este artigo apresenta as duas primeiras versões de um curso de formação em serviço para professores de física de Ensino Médio, em que eles visitam todos os espaços do maior complexo de laboratórios científicos brasileiros ...

    • 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 ...

    • Shedding synchrotron light on teacher training 

      Acioly, Vitor; Paiva, Thereza Cristina de Lacerda; Azevedo, Gustavo de Medeiros; Rocha, Tulio Costa Rizuti da; Picoreti, Renan; Santos, Antônio Carlos Fontes dos (2021) [Journal article]

    • Structural and spectroscopic investigation of the charge-ordered, short-range ordered, and disordered phases of the Co3O2BO3 ludwigite 

      Galdino, Carlos William; Freitas, Daniele; Medrano, Cynthia Paola Contreras; Sánchez, D. R.; Souza, Rodolfo Tartaglia; Rabello, L. P.; Mendonça, Alberto Aguiar; Ghivelder, Luis; Continentino, Mucio Amado; Zapata, Maximiliano Jesús Moreno; Pinheiro, Carlos Basílio; Azevedo, Gustavo de Medeiros; Rodríguez-Velamazán, J. A.; Garbarino, Gaston; Núñez-Regueiro, M.D.; Granado, E. (2021) [Journal article]
      Charge ordering is prone to occur in crystalline materials with mixed-valence ions. It is presumably accompanied by a structural phase transition, with possible exceptions in compounds that already present more than one ...