Reduction of intergranular exchange coupling and grain size for high K u CoPt-based granular media: Metal-oxide buffer layer and multiple oxide boundary materials

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

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Investigation of magnetic properties and microstructure of granular media with various multiple oxides as the grain boundary material is reported. Saturation magnetization (Ms), uniaxial magnetocrystalline anisotropy (Ku), and magnetic grain diameter (GD) of the granular media show linear correlation with volume weighted average for melting point (Tm) of each oxides (Tmave). Ku of magnetic grains (Kugrain) shows a trade-off relation with GD that it is a big challenge to satisfy both high Kugrain and small GD by only controlling Tmave. To obtain a granular medium with appropriate Kugrain, GD, and low degree of intergranular exchange coupling, the combination of Tmave control of grain boundary material by mixing oxides and employment of a buffer layer are required. Here the degree of intergranular exchange coupling is estimated from the slope of M-H loop at around coercivity (α). By applying this technique, a typical granular medium with Kugrain of 1.0×107 erg/cm3, GD of 5.1 nm, and α of 1.2 is realized.

Original languageEnglish
Article number056510
JournalAIP Advances
Volume8
Issue number5
DOIs
Publication statusPublished - 2018 May 1

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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