Browsing by Author "Chesman, C."

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    Effects of second order surface anisotropy in YIG sputtered onto GGG (100) oriented substrate
    (2019) Oliveira, Alexandre; Chesman, C.; Rodríguez Suárez, Roberto; Da Costa, R. B.; Silva, U. C.; Da Costa, N. P.; Silva, Bruno; Sommer, Rubem Luis
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    Filtering magnetic relaxation mechanisms of YIG(001) thin films using ferromagnetic resonance
    (ELSEVIER, 2020) Oliveira, A. B.; Rodriguez Suarez, R. L.; Correa, M. A.; Bohn, F.; Raza, S. A.; Sommer, R. L.; Chesman, C.
    In this work we used the ferromagnetic resonance (FMR) technique to measure the contributions for the magnetic relaxation in Y3Fe5O12 textured films deposited onto (001) Gd3Ga5O12 by magnetron sputtering. Through the numerical fitting of the angular dependence of the in-plane FMR linewidth measurements we identified the contribution of the Gilbert, two-magnon and mosaicity relaxation mechanisms. Regarding to the line broadening due to two-magnon mechanism, we interpreted it as a result of rectangular defects distributed over the film plane. The overall defects were decomposed into three crystallography direction chosen according to the in-plane FMR resonance field experimental results. We observed the two-magnon scattering rate being relevant for YIG thickness below 150 nm. Although it is also present for thicker samples, the Gilbert mechanism dominates with mosaicity being very important to corroborate the shape of the angular dependence, but with small amplitude. We point out the relevance of our finding regarding two-magnon scattering effect in YIG thin films, directly impacting in an overestimation of the spin pumping contribution to the FMR line broadening in YIG/ heavy-metal systems.
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    Spin pumping contribution to the magnetization damping in Tm3Fe5O12/W bilayers
    (2022) Oliveira, A. B.; Rodriguez-Suarez, R. L.; Vilela-Leao, L. H.; Vilela, G. L. S.; Gamino, M.; Silva, E. F.; Bohn, F.; Correa, M. A.; Moodera, J. S.; Chesman, C.
    In this work, thulium iron garnet (Tm3Fe5O12 - TmIG (20 nm)/Tungsten(W)(t) bilayers, sputtered on top of gadolinium gallium garnet (111) substrate, were used to investigate spin pumping (SP) line broadening mechanism in Ferromagnetic Resonance (FMR). The TmIG, films prior and after tungsten cap layer deposition, were investigated employing FMR and X-ray diffraction techniques. The TmIG films showed (1 1 1) orientation and perpendicular magnetic anisotropy (PMA). Due to the interface TmIG/W, when the TmIG magnetization is in resonance a spin current is pumped out the TmIG into the W layer, increasing the damping of the magnetization. Measuring the out-of-plane angular dependence of the FMR resonance field and linewidth, we were able to obtain solely the SP contribution to the line broadening, filtering Gilbert, mosaicity, and two magnon scattering mechanisms.
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    Thickness 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.