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Publication Citation: Determination of spin pumping as a source of linewidth sputtered Co90Fe10/Pd multilayers by use of broadband ferromagnetic resonance spectroscopy

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Author(s): Justin M. Shaw; Hans T. Nembach; Thomas J. Silva;
Title: Determination of spin pumping as a source of linewidth sputtered Co90Fe10/Pd multilayers by use of broadband ferromagnetic resonance spectroscopy
Published: February 10, 2012
Abstract: We performed a systematic study of damping in Co90Fe10/Pd multilayers by use of broadband (1‹ 60 GHz) ferromagnetic resonance (FMR) spectroscopy in the perpendicular geometry. The data were fitted with the conventional Landau-Lifshitz equation in conjunction with an inhomogeneous contribution to linewidth {Δ}H0. Samples were prepared with net perpendicular anisotrpy field values ranging from -0.5 to +1.2 T. {Δ}H0 shows a dependence on the perpendicular anisotropy, through the Landau-Lifshitz damping parameter α, which ranged from 0.016 to 0.04, exhibits no trend as a function of anisotropy. We explain the wide variation of α as a result of spin-pumping from Co90Fe10 into adjacent nonmagnetic layers. We use a quantitative model for spin pumping that includes the intrinsic spin-mixing conductance at the Co90Fe10/Pd interface and the spin-diffusion length of Pd, which were experimentally measured at room temperature to be (1.07 {plus or minus} 1019 m-2 and 8.6 {plus or minus} 1.0 nm, respectively. We quantitatively show how α is enhanced by spin pumping through an FMR investigation of individual Pd/CoFe/Pd, and Pd/CoFe/Pd/CoFe/Pd layer structures.
Citation: Physical Review B
Keywords: Ferromagnetic resonance;perpendicular anisotropy;spin-pumping;damping
Research Areas: Magnetic materials, Thin-Films, Nanomagnetics