FMR study on spin-sprayed Ni-Zn-Co ferrite films with high permeability usable for GHz noise suppressors

Koichi Kondo, Tatsuya Chiba, Shigeyoshi Yoshida, Satoshi Okamoto, Yutaka Shimada, Nobuhiro Matsushita, Masanori Abe

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

We previously revealed that spin sprayed Ni-Zn ferrite films had a weak in-plane uniaxial magnetic anisotropy induced parallel to the liquid flow direction during the spin spraying. Adding a small amount of Co to the films, we made the uniaxial magnetic anisotropy definitely strong. The imaginary part of the complex permeability (μ = μ′ - jμ″) of the Co-containing films measured in the remanence state exhibited a dual step-like dispersion. In order to reveal the influence of magnetic anisotropy of the films on the magnetic resonance, we deposited, in this study, films #1 (Ni 0.17Zn0.22Fe2.61O4) and #2 (Ni 0.19Zn0.20Co0.03Fe2.58O 4) by spin spray ferrite plating at 90°C. The imaginary permeability in the remanence state of the film #1 (which exhibited no definite in-plane magnetic anisotropy) had a maximum at about 450 MHz, which increased with increasing external dc magnetic field, Hdc in the range of 1-3 GHz to give a similar spectrum to that of the film #2. The resonance field, HR of the film #2 under Hdc of 1-2 kOe, which was strong enough to saturate the magnetization, exhibited a prominent in-plane angular dependence, while HR of the film #1 exhibited a very weak angular dependence. The difference between the maximum and the minimum values of H R for the film #2 was about 60 Oe. This means that the film #2 consists of two regions, one with a crystalline anisotropy field having an in-plane isotropic distribution due to the cubic spinel structure, and the other with an induced uniaxial anisotropy field, Hk of about 60 Oe. Assigning Hk of 60 Oe, we calculated the natural resonance frequency, fr as 1.6 GHz. This value approximately coincided with that of the higher frequency step of μ″ for the film #2 in the remanence state. This suggests that the magnetic loss in the remanence state for the films like #2 (which exhibit prominent uniaxial anisotropy induced in film plane) is ascribed to the two regions described above.

Original languageEnglish
Pages (from-to)3463-3465
Number of pages3
JournalIEEE Transactions on Magnetics
Volume41
Issue number10
DOIs
Publication statusPublished - 2005 Oct 1

Keywords

  • Complex permeability
  • Ferrite plating
  • Ferromagnetic resonance (FMR)
  • Ni-Zn(-Co) ferrite film

ASJC Scopus subject areas

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

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