Addition of SiO_2 to Increase Coercivity and Squareness Ratio of Ba Ferrite Films for Perpendicular Magnetic Recording Media(Special Issue on Selected Papers from the 4th Asian Symposium for Information Storage Technology)

概要

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SiO_2-added Ba ferrite(BaM:SiO_2)films were prepared using BaFe_<12>Si_<0.18>O_x targets. BaM:SiO_2 films exhibited perpendicular coercivity H_<c⊥> of over 4.2kOe and squareness ratio of 0.83, although saturation magnetization M_s decreased by about 15%. The angular dependence of coercivity H_c and remanent coercivity H_r were investigated to explain the magnetization reversal mechanism. Intergranular interactions in the films were also evaluated. The magnetization reversal mode of Ba ferrite films with and without SiO_2 additives is not coherent rotation but appears to be the curling mode. The origin of the high coercivity of BaM:SiO_2 films is different from that of Al-substituted Ba ferrite films. It seemed that SiO_2 additives and the defects caused by them decreased M_s and prevented the expansion of reversed domains in the magnetization reversal process, similarly to some pinning effects, and caused high H_<c⊥> of 4.2-5.1kOe in BaM:SiO_2 films.
社団法人電子情報通信学会の論文
2000-09-25