High-Frequency Soft Magnetic Properties of Co-SiO2 Nanogranular Films With Large Out-of-Plane Magnetic Anisotropy

Hanae Kijima-Aoki, Shigeru Takeda, Shigehiro Ohnuma, Hiroshi Masumoto

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


For their use as flexible frameworks in high-frequency electromagnetic devices, soft magnetic thin films must have a high relative permeability μ up to frequencies of the order of 10 GHz and must overcome directional limitations. In this study, we demonstrate full in-plane, high-frequency, soft magnetic performance of Cox-(SiO2)1-x nanogranular films with large out-of-plane anisotropy. For a film with Co concentration x = 0.52, we obtained a high value μ = 4 up to the resonance frequency of 13 GHz for every direction in the film plane. The fine magnetic-maze-domain structure that we observed using magnetic force microscopy was unaffected by the application of an external magnetic field. Both the large out-of-plane anisotropy fields of a few thousand oersteds and the negligibly small remanent magnetization contribute to produce a resonance frequency greater than 10 GHz and to enable magnetically isotropic conditions in the film plane, with high reversibility in external magnetic fields. This film with the large out-of-plane anisotropy promises to be a useful material for applications in fully directional and flexible designs of electromagnetic devices.

Original languageEnglish
Article number3704205
JournalIEEE Magnetics Letters
Publication statusPublished - 2018 Jun 27


  • Microwave magnetics
  • eddy current
  • high-frequency permeability
  • magnetic maze domains
  • nanogranular films
  • out-of-plane magnetic anisotropy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials


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