B2O3: Grain boundary material for high-Ku CoPt–oxide granular media with low degree of intergranular exchange coupling. (28th June 2016)

• Record Type: Journal Article
• Authors: Tham, Kim Kong; Hinata, Shintaro; Kushibiki, Ryosuke; Saito, Shin
• Is Part Of: Japanese journal of applied physics. Volume 55:Number 7(2016:Jul.)Supplement 3
• Publication Date: 2016-06-28
• Subjects: Physics -- Periodicals; 621.05
• DOI: 10.7567/JJAP.55.07MC06
• Languages: English
• ISSNs: 0021-4922

Abstract

Abstract: The magnetic properties and structures of Co80 Pt20 –30 vol % oxide (ZrO2, Cr2 O3, Y2 O3, Al2 O3, MnO, TiO2, WO2, SiO2, Mn3 O4, WO3, Co3 O4, MoO3, and B2 O3 ) 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 ( ) and perpendicular magnetic anisotropy ( ) are obtained; the increases in and 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 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–B2 O3 granular medium has the highest coercivity ( H c ) and ratio of H c to the magnetic anisotropy field ( ) of 8.0 kOe and 0.4, with and of 1115 emu/cm 3 and 1.1 × 10 7 erg/cm 3, respectively. 4) The CoPt–B2 O3 granular medium has well-isolated and columnar growth magnetic grains with an average grain size of 6.5 nm.