Browsing by Author "Rezende, S. M."
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- ItemAnalytical solutions for the magnon frequencies at high-symmetry points of the Brillouin zone in anisotropic kagome antiferromagnets(2021) Rodriguez-Suarez, R. L.; Rezende, S. M.The knowledge of the magnon dispersion relations in antiferromagnetic materials with nontrivial spin textures has considerable interest to the understanding of magnonic and spintronic phenomena involving these materials. One particularly interesting nontrivial spin texture existing in several antiferromagnets has spins at an angle of 120 degrees with the in-plane neighbors and arranged in kagome lattices. Here we present a spin-wave calculation for antiferromagnets with kagome spin lattices considering exchange and single-ion anisotropy interactions between the spins. The theory yields exact analytical expressions for the frequencies of magnons at high-symmetry points of the Brillouin zone, that can be readily use to obtain the interaction parameters from experimental data with one-and two-magnon inelastic light scattering. The analytical expressions are used to obtain the field parameters for the kagome lattice antiferromagnet L1(2)-IrMn3 from four experimentally measured frequencies. Both exchange field parameters are in reasonable agreement with the values obtained with ab initio calculations, while the anisotropy field is in very good agreement with the one calculated with atomistic spin models and Monte Carlo simulations.
- ItemDiffusive magnonic spin transport in antiferromagnetic insulators(2016) Rezende, S. M.; Rodríguez Suárez, Roberto; Azevedo, A.
- ItemElectrical detection of ferromagnetic resonance in single layers of permalloy : evidence of magnonic charge pumping(2015) Azevedo, A.; Cunha, R. O.; Estrada, F.; Santos, O.; Mendes, J. B. S.; Vilela, L. H.; Rodríguez Suárez, Roberto; Rezende, S. M.
- ItemEnhanced spin current transmissivity in Pt/CoFe2O4 bilayers with thermally induced interfacial magnetic modification(2023) Gamino, M.; Oliveira, A. B.; Maior, D. S.; Ribeiro, P. R. T.; Machado, F. L. A.; Mori, T. J. A.; Correa, M. A.; Bohn, F.; Rodriguez-Suarez, R. L.; Fontcuberta, J.; Rezende, S. M.We report on processes of generation of spin current and conversion into charge current in CoFe2O4/Pt bilayers by means of spin Hall magnetoresistance (SMR) and spin Seebeck effect (SSE) experiments. Specifically, we explore (001) full-textured CoFe2O4 (CFO) thin films grown onto (001)-oriented SrTiO3 substrates, covered with Pt layers deposited under two different conditions: one at room temperature and another at high temperature (400 degrees C). The x-ray absorption spectroscopy measurements indicate that the Pt layer deposited at high temperature induces an interfacial magneticlike phase (Fe,Co)-Pt alloy, which influences the magnetic behavior of the structure and is responsible for the enhancement of the spin transmission at the interface. By analyzing the SMR data, we conclude that collinear and noncollinear magnetic domains coexist at the CFO-(Fe,Co)-Pt interface. By combining the data from the SMR and SSE measurements, we obtain the ratios between the values of the spin Hall angle (theta SH) and between the ones of the spin-mixing conductance (g up arrow down arrow that while the value of theta SH decreases by one-half with the heat treatment, the value of g up arrow down arrow one order of magnitude. We interpret the increase of g up arrow down arrow eff in terms of unexpected magnetic reconstructions, which produce an enhancement of the magnetic moment arisen at the interface. Since the spin-mixing conductance determines the efficiency of the spin current transmission through the interface, the spinel ferrite cobalt in contact with a normal metal with a suitable heat treatment becomes a promising material for spintronics device applications.
- ItemMagnon dispersion relations in the noncollinear antiferromagnet IrMn3(2020) Rezende, S. M.; Mendes, J. B. S.; Maior, D. S.; Abrao, J. E.; Azevedo, A.; Rodríguez Suárez, Roberto
- ItemMagnon-mediated spin currents in Tm3Fe5O12/Pt with perpendicular magnetic anisotropy(2020) Vilela, G. L. S.; Abrao, J. E.; Santos, E.; Yao, Y.; Mendes, J. B. S.; Rodríguez Suárez, Roberto; Rezende, S. M.; Han, W.; Azevedo, A.; Moodera, J. S.
- ItemMode locking of spin waves excited by direct currents in microwave nano-oscillators(2007) Rezende, S. M.; Rodríguez Suárez, Roberto
- ItemRotatable anisotropy on ferromagnetic/antiferromagnetic bilayer investigated by Brillouin light scattering(2018) Rodríguez Suárez, Roberto; Oliveira, A. B.; Estrada, F.; Maior, D. S.; Arana, M.; Santos, O. Alves; Azevedo, A.; Rezende, S. M.
- ItemSimultaneous spin pumping and spin Seebeck experiments with thermal control of the magnetic damping in bilayers of yttrium iron garnet and heavy metals: YIG/Pt and YIG/IrMn(2017) Holanda, J.; Alves Santos, O.; Rodríguez Suárez, Roberto; Azevedo, A.; Rezende, S. M.
- ItemSpin Seebeck effect in the antiferromagnet nickel oxide at room temperature(2017) Holanda, J.; Maior, D. S.; Santos, O. Alves.; Vilela Leao, L. H.; Mendes, J. B. S.; Azevedo, A.; Rodríguez Suárez, Roberto; Rezende, S. M.
- ItemSpin-current to charge-current conversion and magnetoresistance in a hybrid structure of graphene and yttrium iron garnet(2015) Mendes, J. B. S.; Alves Santos, O.; Meireles, L. M.; Lacerda, R. G.; Vilela Leao, L. H.; Machado, F. L. A.; Rodríguez Suárez, Roberto; Azevedo, A.; Rezende, S. M.
- ItemSpin-flop transition in the easy-plane antiferromagnet nickel oxide(2017) Machado, F. L. A.; Ribeiro, P. R. T.; Holanda, J.; Rodríguez Suárez, Roberto; Azevedo, A.; Rezende, S. M.
- ItemSurface and volume modes of polarization waves in ferroelectric films(2024) Rodriguez-Suarez, R. L.; Zhou, X. -H.; Cai, C. Y.; Tang, P.; Yu, T.; Bauer, G. E. W.; Rezende, S. M.We investigate the characteristic modes of polarization waves in ferroelectric films. This is motivated by the recent surge of interest in the excitations of the ferroelectric order inspired by the duality between electric dipoles in ferroelectrics and magnetic dipoles in ferromagnets that has led to the introduction of the area of ferronics by analogy to magnonics. We report that a ferroelectric film supports surface and volume modes of polarization waves, analogous to the surface and volume magnetostatic spin-wave modes in a ferromagnetic film. However, while in ferromagnets each type of mode has only one (positive) frequency band, in a ferroelectric film the surface and volume modes have two frequency bands each. We present the dependence of the frequencies on the wave vector for both modes for the parameters of the classic ferroelectric LiNbO 3 , with polarization either parallel or perpendicular to the film. The frequencies lie in the low terahertz band that is experimentally accessible.
- ItemThe role of metallic nanoparticles in the enhancement of the spin Hall magnetoresistance in YIG/Pt thin films(2018) Gamino, M.; Silva, E. F.; Alves Santos, O.; Mendes, J. B. S.; Rodriguez-Suarez, R. L.; Machado, F. L. A.; Azevedo, A.; Rezende, S. M.
- ItemTheory for the spin caloritronic nano-oscillator(2022) Rezende, S. M.; Rodriguez-Suarez, R. L.Auto-oscillations of the magnetization in ferromagnetic hybrid nanostructures driven by spin currents produced by a variety of processes have attracted attention for their challenging physics and possible applications, such as microwave assisted magnetic recording, neuromorphic computing, and chip to chip wireless communications. Of particular interest are applications in which the spin current is produced by a thermal gradient in the configuration of the spin Seebeck effect, because it makes it possible to harvest the thermal energy generated in nanodevices. A few years ago, it was demonstrated experimentally that in a simple bilayer made of a thin film of the insulating ferrimagnet yttrium iron garnet in contact with a platinum layer, the application of a temperature difference across the bilayer produced a coherent microwave auto-oscillation. This device was called a spin caloritronic nano-oscillator. Here we show that these experiments are explained quantitatively by a theory based on a mechanism in which one magnon in the spin current splits into two magnons, one of them being the magnon mode resonating at the nanostructure. The theoretical value of the critical temperature gradient necessary to overcome the magnetic damping to produce auto-oscillations is in good agreement with the one employed in the experiments.
- ItemTheory of the spin Seebeck effect in antiferromagnets(2016) Rezende, S. M.; Rodríguez Suárez, Roberto; Azevedo, A.
- ItemThickness dependence of the magnetic anisotropy and dynamic magnetic response of ferromagnetic NiFe films(2017) Silva, E. F.; Corrêa, M. A.; Della Pace, R. D.; Plá Cid, C. C.; Kern, P. R.; Carara, M.; Chesman, C.; Alves Santos, O.; Rodríguez Suárez, Roberto; Azevedo, A.; Rezende, S. M.; Bohn, F.
- ItemUnraveling intricate properties of exchange-coupled bilayers by means of broadband ferromagnetic resonance and spin pumping experiments(2020) Arana, M.; Gamino, M.; Oliveira, A. B.; Holanda, J.; Azevedo, A.; Rezende, S. M.; Rodríguez Suárez, Roberto