Fabrication of 16 nm Thick Granular L1<sub>0</sub> FePt-<i>h</i>BN Thin Film Media
Chengchao Xu, B. S. D. Ch. S. Varaprasad, David E. Laughlin, Jian-Gang Zhu
Abstract
Hexagonal boron nitride ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${h}$ </tex-math></inline-formula> BN) has recently been investigated as a promising grain boundary material (GBM) for the nanogranular structure of L10-FePt-based heat-assisted magnetic recording (HAMR) media. In this study, we systematically investigated FePt- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${h}$ </tex-math></inline-formula> BN granular thin films (7.5 nm) with various <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${h}$ </tex-math></inline-formula> BN concentrations to provide a fundamental understanding of the effect of introducing <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${h}$ </tex-math></inline-formula> BN nanosheets in the medium film on its microstructure and magnetic properties. Following the optimization of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${h}$ </tex-math></inline-formula> BN concentrations, we demonstrated a method to fabricate a thicker recording layer while maintaining the desired nanogranular microstructure. We successfully fabricated the 16 nm thick FePt- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${h}$ </tex-math></inline-formula> BN film with well-isolated columnar grains of diameter 6.4 nm, grain aspect ratio 2.5, and decent magnetic properties ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${H} _{\mathbf {C\bot }}$ </tex-math></inline-formula> = 21.3 kOe and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${H} _{\mathbf {C//}}$ </tex-math></inline-formula> = 5 kOe).