Atomic Cross-Talk at the Interface: Enhanced Lubricity and Wear and Corrosion Resistance in Sub 2 nm Hybrid Overcoats via Strengthened Interface Chemistry.

Kumar, Rajesh; Bharti, Pankaj; Sasikumar, Kiran; Dhand, Chetna; Kumar, Rajeev; Kumar, Pradip; Sankaranarayanan, Subramanian K R S; Dwivedi, Neeraj · Nano Lett · 2022

basic_science · Level V

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Abstract

Friction, wear, and corrosion remain the major causes of premature failure of diverse systems including hard-disk drives (HDDs). To enhance the areal density of HDDs beyond 1 Tb/in<sup>2</sup>, the necessary low friction and high wear and corrosion resistance characteristics with sub 2 nm overcoats remain unachievable. Here we demonstrate that atom cross-talk not only manipulates the interface chemistry but also strengthens the tribological and corrosion properties of sub 2 nm overcoats. High-affinity (HA) atomically thin (∼0.4 nm) interlayers (ATIs, X<sub>HA</sub>), namely Ti, Si, and SiN<sub><i>x</i></sub>, are sandwiched between the hard-disk media and 1.5 nm thick carbon (C) overlayer to develop interface-enhanced sub 2 nm hybrid overcoats that consistently outperform a thicker conventional commercial overcoat (≥2.7 nm), with the C/SiN<sub><i>x</i></sub> bilayer overcoat bettering all other <2 nm thick overcoats. These hybrid overcoats can enable the development of futuristic 2-4 Tb/in<sup>2</sup> areal density HDDs and can transform various moving-mechanical-system based technologies.