B2O3: Grain boundary material for high-Ku CoPt-oxide granular media with low degree of intergranular exchange coupling

Kim Kong Tham, Shintaro Hinata, Ryosuke Kushibiki, Shin Saito

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14 Citations (Scopus)


The magnetic properties and structures of Co80Pt20-30 vol% oxide (ZrO2, Cr2O3, Y2O3, Al2O3, MnO, TiO2, WO2, SiO2, Mn3O4, WO3, Co3O4, MoO3, and B2O3) granular media deposited at room temperature were investigated. As a result, the following were found. 1) By employing oxides with low melting point temperatures as the granular media, magnetic grains with high saturation magnetization (Msgrain) and perpendicular magnetic anisotropy (Kugrain) are obtained; the increases in Msgrain and Kugrain are due to the promotion of the columnar growth of magnetic grains and phase separation or two-phase precipitation between magnetic grains and oxides. 2) The increase in the Kugrain of the granular media followed by the decrease in the melting point of oxides is due to the reduction in the amount of stacking faults. 3) Among these granular media, the CoPt-B2O3 granular medium has the highest coercivity (Hc) and ratio of Hc to the magnetic anisotropy field (Hc=Hkgrain) of 8.0 kOe and 0.4, with Msgrain and Kugrain of 1115 emu/cm3 and 1.1 × 107 erg/cm3, respectively. 4) The CoPt-B2O3 granular medium has well-isolated and columnar growth magnetic grains with an average grain size of 6.5 nm.

Original languageEnglish
Article number07MC06
JournalJapanese journal of applied physics
Issue number7
Publication statusPublished - 2016 Jul

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)

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