Heat-assisted magnetic recording (HAMR) technology promises to enable hard drives with a 100TB capacity in about a decade from now. But HAMR requires all-new record heads with a transducer that heats up platters as well as new types of media. Researchers at the Cambridge Graphene Centre believe that in addition to new heads and platters makers of HDDs will also have to use new graphene-based overcoats to protect platters from damage and corrosion.
Contemporary HDDs that rely on perpendicular magnetic recording (PMR) technology use aluminum or glass platters with CoCrPt–SiO2 nanogranular magnetic films as well as Carbon-based overcoats (COCs). Hard drives based on HAMR use glass platters with magnetic films featuring high magnetocrystalline anisotropy to ensure very small grains, such as an iron platinum alloy (e.g., L10–FePt). Researchers at the Cambridge Graphene Centre believe that traditional COCs are not optimal for HAMR drives since they will have to handle extreme temperatures for long durations.
In a bid to understand viability of graphene-based coatings for hard drive platters, researchers replaced commercial COCs with one to four layers of graphene, and tested resistance, wear, corrosion, thermal stability, and lubricant compatibility. According to the scientists, graphene enables a two-fold decrease in resistance, lowers corrosion by 2.5 times, and reduces wear when compared to COCs.
"This work showcases the excellent mechanical, corrosion and wear resistance properties of graphene for ultra-high storage density magnetic media," said Andrea C. Ferrari, Director of the Cambridge Graphene Centre. "Considering that in 2020, around 1 billion terabytes of fresh HDD storage was produced, these results indicate a route for mass application of graphene in cutting-edge technologies."
Seagate, the only company that ships HAMR HDDs commercially, does not use graphene for its 20TB drives, but as technology matures, it is possible to expect it to switch to new types of overcoats.
A detailed report about the experiment is published at Nature Communications.