Variation of Magnetization Dynamics of Co/Ni Multilayer by Capturing Magnetic Nanoparticles

Y. Otaki, T. Kato, S. Okamoto, N. Kikuchi, D. Oshima, S. Iwata, O. Kitakami

Research output: Contribution to journalArticlepeer-review


[Co (0.29 nm)/Ni (0.71 nm)]10 multilayers were deposited on Ta (30 nm) and Pt (30 nm) buffer layers, and the variation of the magnetization dynamics by the adsorption of Fe3O4 nanoparticles was studied by vector network analyzer-ferromagnetic resonance method. The surface roughness of the Co/Ni multilayer was 0.52 nm, and significantly increased after the adsorption of the Fe3O4 nanoparticles which was captured by large field gradient on the demagnetized Co/Ni multilayer. The anisotropy field Hκ, damping constant α, and anisotropy distribution Δ Hκ of the Co/Ni on Ta buffer layer were 2.6 kOe, 0.012, and 0.32 kOe, respectively. By adsorbing of the Fe3O4 nanoparticles, the stray field from the nanoparticles Hnp was applied to the Co/Ni, and Hκ + Hnp was estimated to increase to 3.7 kOe. Moreover, α and Δ Hκ also increased to 0.020 and 0.42 kOe by the adsorption, respectively. Similarly, Hκ + Hnp,α, Δ Hκ of Pt buffered Co/Ni also increased from 2.4 kOe, 0.033, 0.43 kOe to 4.2 kOe, 0.055, 0.53 kOe, respectively. These results suggest that the adsorption of Fe3O4 nanoparticles significantly modifies the magnetization dynamics of Co/Ni multilayer.

Original languageEnglish
Article number8365157
JournalIEEE Transactions on Magnetics
Issue number11
Publication statusPublished - 2018


  • Anisotropy field
  • Co/Ni multilayers
  • Feâ Oâ ., nanoparticles
  • Gilbert damping
  • ferromagnetic resonance (FMR)

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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