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

Abstract

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 Tm second oxide together with B2O3 for the grain boundary material, comparable magnetic properties with that of the single oxide granular media and smaller crystallite size evaluated by X-ray diffraction (GDinplane) 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 boundary material, showing comparable average Ms and Ku of 806 emu/cm3 and 7.7×106 erg/cm3 with that of the single B2O3 and smaller GDinplane 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.

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

“…Generally, for the grain boundary materials, oxides material which do not dissolve into the CoPt metal, such as SiO 2 , 3 8,9 Furthermore, by mixing low T m B 2 O 3 with high T m oxides, media with small magnetic grain size can be obtained. 10 It is also shown that the introduction of a buffer layer (BL) underneath the granular media has a great impact on promoting the intergranular exchange decoupling of the media. 11 However, the relation between magnetic properties and T m in a Electronic mail: tham@ml.tanaka.co.jp the granular media with multiple oxides and the synergetic effect of BL and multiple oxides on the media have not been clarified yet.…”

Effect of melting point of grain boundary material on nanostructure and magnetic properties of L10 type FePt granular media

“…For a conventional hcp CoPt-oxide based granular medium deposited at RT, the non-magnetic oxides are precipitated at grain boundaries on the c-plane oriented Ru underlayer with a bumpy structure. [1][2][3] This prevents contact between the adjacent magnetic grains and realizes a columnar structure. The critical thickness of homogeneous granular structure along the thickness direction (d cri ), the amount of stacking faults (P fcc ), and K u are all strongly dependent on the melting point (T m ) of GBM.…”

Surface and Microstructure Analysis of CoCrPt Film on RuCoCrX (X = Ti, Re) Intermediate Layers

“…The CoCrPt (oxides) perpendicular magnetic anisotropy thin films have been applied in current perpendicular magnetic recording media for long periods of time but are still required to improve the properties in the near future [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Although ordered L1 0 -FePt with higher perpendicular anisotropy has been promised for future ultra-high density heat-assisted magnetic recording media [15][16][17], improvements of the intermediate-, exchange coupling-and capping-layer are needed to optimize the magnetic properties and microstructure of CoCrPt-oxide granular films for next-generation devices.…”