Publications Scientifiques

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    Magnetic properties of Fe56Pd44−xGdx thin films
    (American Institute of Physics, 2024) Sahari, Mohamed Abdennour; Olivetti, Elena Sonia; Magni, Alessandro; Fiore, Gianluca; Boudissa, Mokhtar; Tiberto, Paola; Bahamida, Saida; Coïsson, Marco
    In this paper, we have studied the effect on the structure and magnetic properties of partial Pd substitution by Gd in Fe-Pd thin films of nominal composition Fe56Pd44−xGdx (x = 1, 3, 5, and 7), deposited onto Si(100) and Si(100)/SiO2 substrates by thermal evaporation. Several techniques contribute to the characterization of their microstructure and magnetic properties, such as x-ray diffraction (XRD), scanning electron microscopy, alternating gradient field magnetometry, and magnetic force microscopy (MFM). X-ray diffraction shows that the as-deposited films are either amorphous or contain a disordered FePd phase, depending on the film thickness. The transformation of disordered fcc-FePd into ordered fct-FePd has been induced by a heat treatment at 530 °C for 4 h. The addition of gadolinium leads to a reduction in the coercivity as a consequence of the emergence of soft phases and of the progressive reduction of the fct-FePd phase, which is primarily responsible for the observed maze magnetic domains. The exchange coupling between the soft phase and the hard fct-FePd phase is demonstrated by first-order reversal curves (FORCs).
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    Electrostatic solitary structures in a nonthermal plasma
    (2007) Annou, K.; Bahamida, Saida; Annou, R.
    An investigation on the effect of dust temperature and dust streaming on dust acoustic solitary waves in unmagnetized dusty plasma, whose constituents are inertial charged dust grains, non-thermal electrons and ions has been conducted. Sagdeev pseudo potential method which takes into account the full nonlinearity of plasma equations is used here to study solitary wave solution
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    Effects of nonthermal ion distribution and dust temperature on nonlinear dust acoustic solitary waves
    (2007) Annou, K.; Bahamida, Saida; Annou, R.
    An investigation of dust-acoustic solitary waves in unmagnetized dusty plasma whose constituents are inertial charged dust grains, Boltzmannian electrons and nonthermal ions has been conducted taking into account finite dust temperature. The pseudo-potential been used to study solitary solution. The existence of solitary waves of a negative potential is reported
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    Ion-acoustic solitons in electron positron nonthermal plasma
    (2007) Bahamida, Saida; Annou, K.; Annou, R.
    Electron-positron plasmas are believed to exist in the early universe, in active galactic nuclei, and in pulsar magnetospheres. Most of the astrophysical plasmas usually contain ions as well in addition to electrons and positrons. In this work, the ion-acoustic solitons are investigated in three-component plasmas, whose constituents are inertial ions, nonthermal electrons, and Boltzmannian positrons. The properties of stationary structures are studied by pseudopotential approach, which is valid for large amplitude. It is found that the conditions which support the existence of solitons are altered
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    Effects of vortex-like electron-positron distribution on solitary waves in plasma
    (2007) Bahamida, Saida; Annou, K.; Annou, R.
    Electron-positron plasmas are believed to exist in the early universe, in active galactic nuclei, and in pulsar magnetospheres. Most of the astrophysical plasmas usually contain ions as well in addition to electrons and positrons. In this work, the ion-acoustic solitons are investigated in three-component plasmas, whose constituents are inertial ions, vortex-like electrons and positron. The properties of stationary structures are studied by pseudo-potential approach, which is valid for large amplitude
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    A comparative structural and magnetic study of Fe100-xPdx(x=15, 20 and 36) thin films deposited on Si (100) and glass substrates
    (Elsevier, 2015) Bahamida, Saida; Fnidiki, A.; Laggoun, A.; Guittoum, A.
    Various structural and magnetic characterization techniques have been used to investigate Fe100-xPdx (x=15, 20 and 36) thin films deposited onto silicon and glass substrates, by thermal evaporation technique. X-ray diffraction analysis shows the presence of supersaturated solid solution with bcc structure for Pd concentrations of 15% and 20%. However, for 36% of Pd, in addition to the supersaturated α-FePd (bcc) phase, another disordered FePd3 phase with fcc structure is present. At 20 at% Pd, the magnetic characterization shows a saturation of the bcc (α-FePd) phase and the appearance of the fcc phase. The correlation between the structure and magnetic properties allows us to compare the two substrates effects on deposited thin films. As results, the measurements indicate that the grain size D, the thin film thickness and the d(110) spacing significantly affect the magnetic coercivity HC. The Fe-Pd alloys deposited on a monocrystalline Si (100) and glass substrate show that the coercivity HC is given by the random anisotropy model. & 2015
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    Magnetic properties of bcc and bcc-fcc Fe-Pd alloys produce by thermal evaporation technique
    (Elsevier, 2014) Bahamida, Saida; Laggoun, Ali; Guittoum, Abderrahim; Fnidiki, Abeslem; Boudissa, Mokhtar