Measurement of spin mixing conductance in Ni81Fe19/α-W and Ni81Fe19/β-W heterostructures via ferromagnetic resonance (original) (raw)
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Investigation of Spin-Pumping and -Transport in the Ni80Fe20/Pt/Co Asymmetric Trilayer
arXiv (Cornell University), 2024
Ferromagnet1/Non-magnetic Metal/Ferromagnet2 (FM1/NM/FM2) trilayers have garnered considerable attention because of their potential in spintronic applications. A thorough investigation of the spin transport properties of these trilayers is therefore important. Asymmetric trilayers, particularly those including Platinum (Pt) as a spacer are less explored. Pt mediates exchange coupling between the two FM layers and thus offers a unique platform to investigate the spin-transport properties under indirect exchange coupling conditions through the spin-pumping mechanism. We study the static and dynamic magnetic properties of Ni80Fe20/Pt(t)/Co trilayer system through vibrating sample magnetometry (VSM) and spin-pumping based on ferromagnetic resonance (FMR) spectroscopy by varying the Pt spacer thickness. Though a powerful method for characterizing the dynamic magnetic properties of FM layers, FMR is seldom the only technique used for investigating spin transport characteristics of asymmetric trilayers. Our analytical focus on the acoustic mode, facilitated by the distinct magnetizations of the Ni80Fe20 and Co layers, allows for the isolation of individual layer resonances. The derived spin-pumping induced damping () of the Ni80Fe20 and Co layers reveals a direct dependence on the Pt spacer thickness. Furthermore, fitting of the weighted average of the damping parameters to the of acoustic mode reveals that the observed FMR spectra is indeed a result of the in-phase precession of the magnetizations in two FM layers. The extracted effective spin-mixing conductance (↑↓) varies with the FM/NM interface, specifically 1.72 × 10 19 −2 at the Ni80Fe20/Pt and 4. 07 × 10 19 −2 at the Co/Pt interface, indicating a strong correlation with interfacial characteristics. Additionally, we deduce the spin diffusion length in Pt to be between 1.02 and 1.55 nm and calculate the interfacial spin transparency () and spin current densities, highlighting significant disparities between the Ni80Fe20/Pt and Co/Pt interfaces. This detailed analysis enhances our understanding of spin transport in Ni80Fe20/Pt/Co trilayers. It offers insights important for advancing spintronic device design and lays the groundwork for future theoretical investigations of trilayer system. I.
Structural Phase-Dependent Giant Interfacial Spin Transparency in W/CoFeB Thin-Film Heterostructures
ACS Applied Materials & Interfaces
Pure spin current has transfigured the energy-efficient spintronic devices and it has the salient characteristic of transport of the spin angular momentum. Spin pumping is a potent method to generate pure spin current and for its increased efficiency high effective spin-mixing conductance (Geff) and interfacial spin transparency (T) are essential. Here, a giant T is reported in Sub/W(t)/Co20Fe60B20(d)/SiO2(2 nm) heterostructures in beta-tungsten (β-W) phase by employing all-optical time-resolved magneto-optical Kerr effect technique. From the variation of Gilbert damping with W and CoFeB thicknesses, the spin diffusion length of W and spinmixing conductances are extracted. Subsequently, T is derived as 0.81 ± 0.03 for the β-W/CoFeB interface. A sharp variation of Geff and T with W thickness is observed in consonance with the thickness-dependent structural phase transition and resistivity of W. The spin memory loss and two-magnon scattering effects are found to have negligible contributions to damping modulation as opposed to spin pumping effect which is reconfirmed from the invariance of damping with Cu spacer layer thickness inserted between W and CoFeB. The observation of giant interfacial spin transparency and its strong dependence on crystal structures of W will be important for pure spin current based spin-orbitronic devices.
Magnetotransport properties and electronic structure of Ni81Fe19/W90Ti10 multilayers
The magnetotransport properties of Ni81Fe19/W90Ti10 multilayers are investigated. The effect of the thicknesses of the magnetic (Ni81Fe19) and non magnetic (WTi) layers on the magnetoresistance (MR) are theoretically discussed in the framework of the Johnson-Camley semiclassical approach based on the Boltzmann transport equation. A comparison between the calculated and measured MR ratios is obtained. The observed MR ratio oscillates for WTi layer thickness with an average period of 10 Å. A weak MR(tNiFe) ratio for a fixed tWTi is obtained and it presents a maxima peak of the MR with a value of 0.8% located at tNiFe = 50Å. In addition, electronic and magnetic properties of multilayers are investigated by self consistent ab initio calculations based on Korringa–Kohn–Rostocker (KKR). Spin polarized within the framework of the Coherent Potential Approximation (CPA) is considered for calculations
Magnetic properties of Ni81Fe19/W90Ti10 multilayers
Journal of Magnetism and Magnetic Materials, 2003
The magnetization and anisotropy of Ni 81 Fe 19 /W 90 Ti 10 multilayers prepared by DC sputtering are presented. At high-angle X-ray diffraction, weak superlattice peaks appear around the NiFe (1 1 1) diffraction line, which indicate a fiber texture /1 1 1S for NiFe. The magnetization decreases with NiFe layer thickness t NiFe and the analysis of the results at 300 K indicates the presence of 6 ( A thick dead Ni 81 Fe 19 layer. The ferromagnetic resonance (FMR) spectra are obtained with the applied magnetic field parallel and perpendicular to the film plane at 300 K. Complicated spin-wave resonance spectra were observed and analyzed. From FMR, a negative value for Ni 81 Fe 19 /W 90 Ti 10 interface anisotropy is obtained. r
Angular dependence of ferromagnetic resonance in Tb-doped Ni80Fe20 thin films
Journal of Alloys and Compounds, 2014
The mechanisms of angular dependence of ferromagnetic resonance (FMR) linewidth of dilute Tb doping in Ni 80 Fe 20 thin films are investigated by experimental approach and the theoretical fitting by considering the contributions from intrinsic spin-orbit coupling, two-magnon scattering and inhomogeneous broadening. It is shown that the damping coefficient a, by intrinsic contribution extracted from FMR linewidth, is increased by more than 50 times as the Tb concentration increases to 8.4%, indicating that the spinorbit coupling of this system increases with the introduction of Tb impurities. The magnetic anisotropy constants K 1 and K 2 are obtained and show an increasing trend from negative to positive, which implies that the Tb dopants could enhance the perpendicular anisotropy.
Structural Phase Dependent Giant Interfacial Spin Transparency in W/CoFeB Thin Film Heterostructure
2020
Pure spin current has transfigured the energy-efficient spintronic devices and it has the salient characteristic of transport of the spin angular momentum. Spin pumping is a potent method to generate pure spin current and for its increased efficiency high effective spin-mixing conductance (Geff) and interfacial spin transparency (T) are essential. Here, a giant T is reported in Sub/W(t)/Co20Fe60B20(d)/SiO2(2 nm) heterostructures in \beta-tungsten (\beta-W) phase by employing all-optical time-resolved magneto-optical Kerr effect technique. From the variation of Gilbert damping with W and CoFeB thicknesses, the spin diffusion length of W and spin-mixing conductances are extracted. Subsequently, T is derived as 0.81 \pm 0.03 for the \beta-W/CoFeB interface. A sharp variation of Geff and T with W thickness is observed in consonance with the thickness-dependent structural phase transition and resistivity of W. The spin memory loss and two-magnon scattering effects are found to have negli...
Physical Review Letters, 2010
Using a formulation of first-principles scattering theory that includes disorder and spin-orbit coupling on an equal footing, we calculate the resistivity ρ, spin flip diffusion length l sf and the Gilbert damping parameter α for Ni1−xFex substitutional alloys as a function of x. For the technologically important Ni80Fe20 alloy, permalloy, we calculate values of ρ = 3.5 ± 0.15 µOhm-cm, l sf = 5.5 ± 0.3 nm, and α = 0.0046 ± 0.0001 compared to experimental low-temperature values in the range 4.2 − 4.8 µOhm-cm for ρ, 5.0 − 6.0 nm for l sf , and 0.004 − 0.013 for α indicating that the theoretical formalism captures the most important contributions to these parameters.
Ferromagnetic resonance in ultrathin Ni(111) /W(110)
Journal of Magnetism and Magnetic Materials, 1991
20, 25 and 30A thin Ni(lll) films have been prepared on W(II0) in UHV and characterized by low energy electron diffraction and Auger spectroscopy. FMR measurements at 9 GHz have been used to study the magnetic properties between 300 and 600 K. The effective in and out of plane anisotropies increase with decreasing temperature and film thickness. These anisotropies are decomposed into surface (K s) and volume (K v) contributions. K, is 30 times larger than in bulk Ni, due to internal stress caused by the lattice mismatch between Ni and W.
Ferromagnetic resonance study of sputtered NiFe/V/NiFe heterostructures
Journal of Magnetism and Magnetic Materials, 2015
The Ni 81 Fe 19 /V/Ni 81 Fe 19 heterostructures has been produced by magnetron sputtering and analyzed by ferromagnetic resonance. Two systems were investigated: the non symmetrical NiFe(50 Å)/V(t)/NiFe (30 Å) trilayers and the symmetrical NiFe(80 Å)/V(t)/NiFe(80 Å) trilayers, with variable ultrathin V thickness t. Ferromagnetic exchange coupling was evidenced for t below 10 Å by the excitation of the optic mode, in the case of the non symmetrical samples, and by the observation of a single resonance mode for the symmetrical trilayers. For larger V thickness, all samples exhibited two modes, which were attributed to the resonance of the individual NiFe layers with different effective magnetizations. The analysis with the equilibrium and resonance conditions provided the exchange coupling constants and effective magnetizations.