Breaking the 2‐nm Barrier in Hard Disk Drives Using Monolayer Amorphous Carbon Overcoats

ABSTRACT The rapid growth of artificial intelligence (AI) has increased the demand for large‐scale data storage, making hard disk drives (HDDs) indispensable in data centers due to their cost‐effectiveness and stability. To support AI‐driven data requirements, increasing the areal storage density is critical. However, this metric is increasingly constrained by the carbon overcoat (COC), the essential protective layer for magnetic media. Traditional diamond‐like carbon (DLC) can no longer fulfill the stringent demands for ultrathin coatings and high thermal stability required by next‐generation technologies like Heat‐Assisted Magnetic Recording (HAMR) and bit‐patterned media. Here, we introduce monolayer amorphous carbon (MAC) as a superior alternative. MAC is directly grown on the heterogeneous (Fe, Pt, SiO 2 ) HDD surface at low temperatures (∼ 300°C), achieving an uniform 0.8 nm thickness across 2.5‐inch disks. Despite its atomic thickness, MAC demonstrates high corrosion resistance and low roughness comparable to commercial 2.5 nm COCs. Its fully amorphous, sp 2 ‐hybridized structure ensures excellent thermal stability under HAMR‐like conditions (∼450°C) and a low friction coefficient, enabling potential lubricant‐free operation. Replacing traditional COCs with MAC facilitates the development of HDD media capable of achieving 10 Tb/in 2 , addressing the urgent storage demands of the digital era.