Spin pumping at interfaces with ferro- and paramagnetic Fe60Al40 films acting as spin source and spin sink


Spin pumping at interfaces with ferro- and paramagnetic Fe60Al40 films acting as spin source and spin sink

Strusch, T.; Lenz, K.; Meckenstock, R.; Bali, R.; Ehrler, J.; Lindner, J.; Faßbender, J.; Farle, M.; Potzger, K.; Semisalova, A.

We present a study of spin pumping efficiency and determine the spin mixing conductance and spin diffusion length in thin bilayer films based on 3d transition metal alloy Fe60Al40. Due to its magnetostructural phase transition, Fe60Al40 can be utilized as a ferromagnetic (FM) or paramagnetic (PM) material at the same temperature depending on its structural order, thus thin Fe60Al40 film can act as a spin source or a spin sink when interfaced with a paramagnet or a ferromagnet, correspondingly. Ferromagnetic resonance (FMR) measurements were performed in a frequency range of 5 - 35 GHz on bilayer films composed of FM-Fe60Al40 / Pd and PM-Fe60Al40 / permalloy Ni80Fe20. The increase of damping parameter with the thickness of paramagnetic layer was interpreted as a result of spin pumping into a paramagnet. In the first case, the FM-Fe60Al40 acts as a spin source and in the second case PM-Fe60Al40 serves as a spin sink. We determine the spin mixing conductance 𝑔𝑃𝑑↑↓=(3.8±0.5)×1018 m-2 at the FM-Fe60Al40/Pd interface and the spin diffusion length 𝜆𝑃𝑑=9.1 ±2.0 nm in Pd. For the PM-Fe60Al40/permalloy interface we find a spin mixing conductance 𝑔𝐹𝑒𝐴𝑙↑↓=(2.1±0.2)×1018 m-2 and a spin diffusion length 𝜆𝐹𝑒𝐴𝑙=11.9 ±0.2 nm for PM-Fe60Al40. Demonstrated bi-functionality of Fe60Al40 alloy in spin pumping structures may be promising for spintronic applications

Keywords: Ferromagnetic resonance; spin pumping; ferromagnetic films; ferromagnetism; FeAl alloys; spin diffusion; damping; linewidth

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Permalink: https://www.hzdr.de/publications/Publ-32940
Publ.-Id: 32940