Coplanar Waveguide Ferromagnetic Resonance Spectroscopy (CPW-FMR) was used to investigate the spin dynamics of the thin film multilayers Py/Ir vs. Py/Cu/Ir. The properties of both sample sets were evaluated as a function of the Ir thickness. The gyromagnetic ratio, 𝛾, is found to be independent of the Ir thickness and determined to be approximately 29.4 GHz/T for all samples. The magnetization, M, is found to be 7249 G for the Py/Cu/Ir samples compared to 7630 G for the Py standard. For the Py/Ir bilayer, M decreases as Ir thickness increases, ranging from 7641 G to 7293 G. The thickness dependence on M for Py/Ir is believed to be caused by induced perpendicular anisotropy. The inhomogeneous broadening (ΔH0) is nearly double for Py/Ir compared to Py/Cu/Ir. There is a strong enhancement of the Gilbert damping parameter when the Ir layer has a direct interface with magnetic layer (α = 0.023) compared to when the interfaces are interrupted with a Cu layer (α = 0.013). The control sample Py demonstrated a damping parameter consistent with other investigations (α = 0.0084). This indicates the presence of spin memory loss at the interface of Py and Ir. Effective Spin mixing conductance, geff, was found to be 8.8 ± 0.3 nm−2 for Py/Cu/Ir, and 25.2 ± 0.5 nm−2 for the Py/Ir samples. There is a thickness dependence on the damping for the Py/Ir samples that was not observed Py/Cu/Ir samples. This is believed to be related to a proximity effect for the Py-Ir interface. The thickness dependence on the damping for Py/Ir was found to be approximately λ=0.5 ± 0.1 nm.
Materials Science and Engineering (MS)
Department, Program, or Center
School of Chemistry and Materials Science (COS)
White, Thomas, "Ferromagnetic Resonance to Investigate Spin Pumping in Permalloy Multilayers" (2017). Thesis. Rochester Institute of Technology. Accessed from
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