High Ku and small grain size Co80Pt20 granular media with double oxide grain boundary materials consisting of B2O3.

Investigation of magnetic properties and microstructure of granular media with various double oxides including B₂O₃ as the grain boundary material is reported. By adding a high T_m second oxide together with B₂O₃ for the grain boundarymaterial, comparable magnetic properties with that of the single oxide granular media and smaller crystallite size evaluated by X-ray diffraction (GD_inplane) than that of the single oxide granular media can be obtained. Among the evaluated media, the granular medium with B₂O₃- TiO₂ is promising for the grain boundarymaterial, showing comparable average M_s and K_u of 806 emu/cm3 and 7.7×106erg/cm³ with that of the single B₂O₃ and smaller GD_inplane of 4.8 nm than that of the single B₂O₃ of 5.4 nm. In the TEM image, thin grain boundaries inside the grains can be observed which indicates that small grains with one-on-one grains growth is expected when an underlayer with smaller grain size is utilized. [ABSTRACT FROM AUTHOR]