R&D: Comparison of h-BN and Graphene Layers as Grain Boundary Materials for Granular FePt-L10 Thin Films

Arxiv has published an article written by B.S.D.Ch.S. Varaprasad, Chengchao Xu, Data Storage Systems Center, Carnegie Mellon University, Pittsburgh, PA, USA, and Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, USA, Brandon Reese, Data Storage Systems Center, Carnegie Mellon University, Pittsburgh, PA, USA, and Materials Science and Engineering Department, Carnegie Mellon University, Pittsburgh, PA, USA, David E. Laughlin, and Jian-Gang (Jimmy) Zhu, Data Storage Systems Center, Carnegie Mellon University, Pittsburgh, PA, USA, Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, USA, Materials Science and Engineering Department, Carnegie Mellon University, Pittsburgh, PA, USA.

Abstract: “Granular L10-FePt thin films with small columnar grains are essential for heat-assisted magnetic recording media. While hexagonal boron nitride(h-BN) has proven effective for promoting columnar FePt grains, we explored multilayer graphene as an alternative grain boundary material leveraging its structural similarity to h-BN. The FePt granular thin films with carbon-based grain boundary materials(GBMs) were deposited by cosputtering on Si/SiO2 substrates with substrate bias at 650°C. The RF bias and high temperature facilitated formation of interlinked graphene nanoribbons wrapping around FePt grains, yielding 7.5 nm diameter, 8 nm height grains with an order parameter of 0.78 and a perpendicular coercivity of 40 kOe. However, the formation of graphene nanoribbons could not effectively promote columnar structures, likely due to co-existing amorphous carbon in grain boundaries. Optimizing deposition to improve graphene grain boundary quality is necessary to realize this 2D material’s potential for achieving desirable microstructures for HAMR media.“