In-Plane Component Reduction and <i>K</i> _u Enhancement of FePt-Oxide Granular Films by Using (Pt, Ag)-C/FePtCu-C Stacked Granular Buffer Layers

Investigation of nanostructure and magnetic properties of the granular films deposited on stacked buffer layers (BLs) of (Pt, Ag)-C/ FePtCu-C is reported. By optimizing film thickness of the (Pt, Ag)-C/ FePtCu-C BLs, uniaxial magneto-crystalline anisotropy energy (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">u</sub>⊥<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">film</sup>) of 2.7×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> erg/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> was achieved for the Pt-C/FePtCu-C BLs and 2.2×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> erg/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> for the Ag-C/ FePtCu-C BLs. In addition, the amount of magnetic grain with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</i>-axes parallel to the film plane of those granular films is suppressed. Furthermore, FePt grain size of the granular film deposited on Ag-C/ FePtCu-C BLs is smaller than that of deposited on Pt-C/ FePtCu-C BLs. Therefore, the stacked BLs combining (Pt, Ag)-C and FePtCu-C BL satisfy both the requirements for low in-plane (001) components and high <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">u</sub>⊥<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">film</sup>. (Pt, Ag)-C/ FePtCu-C stacked BLs are useful for extending high recording density in HAMR application.