R&D: Understanding Growth of High-Aspect-Ratio Grains in Granular L10-FePt Thin-Film Magnetic Media

APL Materials has published an article written by Chengchao Xu, Data Storage Systems Center, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA, and Electrical and Computer Engineering Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA, Bing Zhou, Tianxiang Du^, Data Storage Systems Center, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA, and Materials Science and Engineering Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA^, B. S. D. Ch. S. Varaprasad, Data Storage Systems Center, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA, and Electrical and Computer Engineering Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA, David E. Laughlin, and Jian-Gang (Jimmy) Zhuh, Data Storage Systems Center, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA, Electrical and Computer Engineering Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA, and Materials Science and Engineering Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.

Abstract: “A systematic investigation has been performed to optimize the microstructure of L1₀-FePt–SiO_x granular thin films as recording media for heat-assisted magnetic recording. The FePt–boron nitride (BN) nucleation layer, which is stable even at 700 °C, is used to control the grain sizes and microstructure during the high-temperature processing. The study finds that films of high-aspect-ratio FePt grains with well-formed silicon oxide (SiO_x) grain boundaries require the grading of the deposition temperature during film growth as well as the grading of the silicon oxide concentration. Well-isolated columnar grains of L1₀-FePt with an average height greater than 11 nm and diameters less than 7 nm have been achieved. Transmission electron microscopy analysis of the microstructures of samples produced under a variety of non-optimal conditions is presented to show how the microstructure of the films depends on each of the sputtering parameters.“