Navegando por Autor "Suarez, Roberto Lazaro Rodriguez"
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Artigo Angular dependence of hysteresis shift in oblique deposited ferromagnetic/antiferromagnetic coupled bilayers(AIP Publishing LLC, 2014-07-17) Oliveira, Alexandre Barbosa de; Suarez, Roberto Lazaro Rodriguez; Michea, Sebastián; Vega, Henrry Ariel; Costa, Antônio Azevedo da; Rezende, Sérgio Machado; Aliagla, Carolina; Denardin, JulianoThe angular dependence of the hysteresis shift has been investigated in ferromagnetic/antiferromagnetic (NiFe/IrMn) bilayers grown by oblique deposition under the influence of a static magnetic field applied perpendicular to the uniaxial anisotropy direction induced during the growth process. It was found that at low oblique deposition angles, the unidirectional anisotropy field is much greater than the uniaxial anisotropy field and the corresponding anisotropies directions are noncollinear. In these conditions, the angular dependence of the hysteresis loop shift exhibits the well know cosine like shape but demanding a phase shift. Contrary to this, at high oblique deposition angle (70 ), the uniaxial anisotropy plays the fundamental role and the anisotropies directions are collinear. In this case, the exchange bias displays a jump phenomenon. The numerical calculations are consistent with the experimental data obtained from magneto-optical Kerr effect and ferromagnetic resonanceArtigo Critical thickness investigation of magnetic properties in exchange-coupled bilayers(American Physical Society, 2011) Suarez, Roberto Lazaro Rodriguez; Leão, Luis Henrique Vilela; Oliveira, Alexandre Barbosa de; Almeida, Jairo Rolim Lopes de; Landeros, Pedro; Rezende, Sergio Machado; Costa, Antonio Azevedo daWe present a systematic investigation of the magnetic properties of two series of polycrystalline ferromagneticantiferromagnetic bilayers (FM-AF) of Ni81Fe19(10nm)/Ir20Mn80(tAF) grown by dc magnetron sputtering. One series was grown at an oblique angle of 50◦ and the other one was grown at 0◦. Ferromagnetic resonance (FMR) was used to measure the exchange bias field HE, the rotatable anisotropy field HRA, and the FMR linewidth H as a function of the antiferromagnetic layer thickness tAF. Three relaxation channels due to isotropic Gilbert damping, anisotropic two-magnon scattering, and mosaicity effects are simultaneously distinguished through the angular dependence of the FMR linewidth. In the regime of small IrMn layer thicknesses, not enough to establish the exchange bias anisotropy, the FMR linewidth shows a sharp peak due to the contribution of the two-magnon scattering mechanism. The results presented here are of general importance for understanding the dynamics of magnetization in the FM-AF structures