The Preparation And Magnetic Properties Of FePt Nanodot Arrays Sputtering On AAO Templates

The patterned magnetic recording technology uses the two-dimensional ordered magnetic nano arrays as recording medium, and it can break the superparamagnetic limit in the conventional continuous magnetic recording medium, and it is possible to increase the recording areal density of a hard disk to 5Tb/in2. The key of patterned recording technology to practical development is to develop a high-performance patterned magnetic recording medium, the FePt become has become a hot topic material in the preparation of the patterned magnetic media due to its ultra high magnetic anisotropy and ultra low superparamagnetic critical dimension.Currently, the preparation process is still one of the major challenges in the research of the patterned magnetic recording, and there are three main approach: one approach is to use etching printing technology, which is very time-consuming and high-costly and can only used for small production. Another approach is the self-assembly of magnetic nanoparticles, but suppress the particle aggregation during annealing and guarantee highly ordered aligning of magnetic easy axis need further study. The last approach is to use porous templates to induce the synthesis of nanostructures, it can effectively solve the above problems in the previous two approaches. This paper used the anodic aluminum oxide(AAO) templates, because of its pore size and thickness can easily be regulated oxidizing conditions.This paper introduced the magnetron sputtering system and its work principle, and microscopic analysis and magnetic properties test of the templates and samples. Then the micron-sized array templates were successfully prepared in Si chip using the traditional lithography and ICP etching technology, and the nano-porous anodized alumina templates with different periods and pore diameters were also fabricated by tuning the experimental parameters during the two-step anodization processes. Finally, Fe Pt nanodot arrays wereprepared by the magnetron sputtering and quantificational etching on AAO templates and the effect of Ag underlayer, annealing temperature and pore diameter on the magnetic properties of FePt nanodot arrays were also discussed in detail. The research results show that Ag underlayer can greatly enhance the perpendicular coercivity of FePt nanodot arrays, the arrays post annealed at 600°C exhibit significant L10 phase and have high hard magnetic properties, AAO templates with pore diameter of 80 nm are more conducive to the deposition of FePt nanoparticles and the improvement of the perpendicular magnetic properties than those with pore diameter of 40 nm.