Atomic Scale Interface Manipulation, Structural Engineering, and Their Impact on Ultrathin Carbon Films in Controlling Wear, Friction, and Corrosion.

Reducing friction, wear, and corrosion of diverse materials/devices using <2 nm thick protective carbon films remains challenging, which limits the developments of many technologies, such as magnetic data storage systems. Here, we present a novel approach based on atomic scale interface manipulation to engineer and control the friction, wear, corrosion, and structural characteristics of 0.7-1.7 nm carbon-based films on CoCrPt:oxide-based magnetic media. We demonstrate that when an atomically thin (∼0.5 nm) chromium nitride (CrNx) layer is sandwiched between the magnetic media and an ultrathin carbon overlayer (1.2 nm), it modifies the film-substrate interface, creates various types of interfacial bonding, increases the interfacial adhesion, and tunes the structure of carbon in terms of its sp(3) bonding. These contribute to its remarkable functional properties, such as stable and lowest coefficient of friction (∼0.15-0.2), highest wear resistance and better corrosion resistance despite being only ∼1.7 nm thick, surpassing those of ∼2.7 nm thick current commercial carbon overcoat (COC) and other overcoats in this work. While this approach has direct implications for advancing current magnetic storage technology with its ultralow thickness, it can also be applied to advance the protective and barrier capabilities of other ultrathin materials for associated technologies.