Ultra-high resistive and anisotropic CoPd-CaF2 nanogranular soft magnetic films prepared by tandem-sputtering deposition

Masayuki Naoe, Nobukiyo Kobayashi, Shigehiro Ohnuma, Tadayoshi Iwasa, Ken Ichi Arai, Hiroshi Masumoto

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Ultra-high resistive and anisotropic soft magnetic films for gigahertz applications are desirable to demonstrate the really practical films. Here we present a study of novel nanogranular films fabricated by tandem-sputtering deposition. Their electromagnetic properties and nanostructure have also been discussed. These films consisted of nanocrystallized CoPd alloy-granules and CaF2 matrix, and a specimen having a composition of (Co0.69Pd0.31)52-(Ca0.31F0.69)48 exhibited distinct in-plane uniaxial anisotropy after uniaxial field annealing with granule growth. Its complex permeability spectra have a ferromagnetic resonance frequency extending to the Super-High-Frequency band due to its higher anisotropy field, and its frequency response was quite well reproduced by a numerical calculation based on the Landau-Lifshitz-Gilbert equation. Furthermore, it was clarified that the CaF2-based nanogranular film exhibits a hundredfold higher electrical resistivity than conventional oxide or nitride-based films. Higher resistivity enables the film thickness to achieve a margin exceeding threefold against eddy current loss. The greater resistivity of nanogranular films is attributed to the wide energy bandgap and superior crystallinity of CaF2 matrix.

Original languageEnglish
Pages (from-to)213-222
Number of pages10
JournalJournal of Magnetism and Magnetic Materials
Volume391
DOIs
Publication statusPublished - 2015 May 22

Keywords

  • Annealing effect
  • Fluoride
  • Nanogranular film
  • Resistivity
  • Skin depth
  • Uniaxial anisotropy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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