Abstract
Achieving magnetic recording densities in excess of 1Tbit/in2 requires not only perpendicular media with anisotropies larger than 7 MJ/m3, making FePt alloys an ideal choice, but also a narrow distribution below 10 nm for a reduced S/N ratio. Such grain size reduction and shape control are crucial parameters for high density magnetic recording, along with high thermal stability. Previous work has shown that the L10 FePt grain size can be controlled by alloying FePt with materials such as C, Ag, and insulators such as AlOx, MgO. Au and Al2O3 also act to segregate and magnetically decouple the FePt grains. Better results were obtained with C with respect to the uniformity of grains and SiO2 with respect to the shape. We present our results on co-sputtering FePt with C or SiO2 (up to 30 vol %) on MgO (001) single crystal substrates at 350 and 500 oC. With C or SiO2 addition we achieved grain size reduction, shape control and isolated structure formation, producing continuous films with high uniformity and a narrow grain size distribution. These additions thus allow us to simultaneously control the coercivity and the S/N ratio. We also will report structural and microstructural properties.
Highlights
Areal density is one of the most important figures of merit for magnetic recording media [1]
Addtion of C leads to a grain size reduction [2], an improvement of main diameter distribution, which is very important in S/N ratio maximization, and to the isolation of the magnetic particles [3,4]
With the addition of SiO2 better control of the coercivity is achieved, a columnar shape is realised with cuboid-like particles which are considered more suitable for the magnetic recording [5]
Summary
Areal density is one of the most important figures of merit for magnetic recording media [1]. Addtion of C leads to a grain size reduction [2], an improvement of main diameter distribution, which is very important in S/N ratio maximization, and to the isolation of the magnetic particles [3,4]. With the addition of SiO2 better control of the coercivity is achieved, a columnar shape is realised with cuboid-like particles which are considered more suitable for the magnetic recording [5].
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