Researchers at the Cambridge Graphene Centre have shown that Graphene can be used for ultra-high
density hard disk drives (HDD), with up to a tenfold jump compared to current technologies.
The study, published in the journal Nature Communications, was carried out in collaboration
with teams at the University of Exeter, India, Switzerland, Singapore, and the US.
HDDs first appeared in the 1950s, but their use as storage devices in personal computers
only took off from the mid-1980s.
They have become ever smaller in size, and denser in terms of the number of stored bytes.
While solid state drives are popular for mobile devices, HDDs continue to be used to store
files in desktop computers, largely due to their favourable cost to produce and purchase.
HDDs contain two major components: platters and a head.
Data are written on the platters using a magnetic head, which moves rapidly above them as they
spin.
The space between head and platter is continually decreasing to enable higher densities.
Currently, carbon-based overcoats (COCs) – layers used to protect platters from mechanical damages
and corrosion – occupy a significant part of this spacing.
The data density of HDDs has quadrupled since 1990, and the COC thickness has reduced from
12.5nm to around 3nm, which corresponds to one terabyte per square inch.
Now, graphene has enabled researchers to multiply this by ten.
The Cambridge researchers have replaced commercial COCs with one to four layers of graphene,
and tested friction, wear, corrosion, thermal stability, and lubricant compatibility.
Beyond its unbeatable thinness, graphene fulfills all the ideal properties of an HDD overcoat
in terms of corrosion protection, low friction, wear resistance, hardness, lubricant compatibility,
and surface smoothness.
Graphene enables two-fold reduction in friction and provides better corrosion and wear than
state-of-the-art solutions.
In fact, one single graphene layer reduces corrosion by 2.5 times.
Cambridge scientists transferred graphene onto hard disks made of iron-platinum as the
magnetic recording layer, and tested Heat-Assisted Magnetic Recording (HAMR) – a new technology
that enables an increase in storage density by heating the recording layer to high temperatures.
Current COCs do not perform at these high temperatures, but graphene does.
Thus, graphene, coupled with HAMR, can outperform current HDDs, providing an unprecedented data
density, higher than 10 terabytes per square inch.
The researcher says demonstrating that graphene can serve as protective coating for conventional
hard disk drives and that it is able to withstand HAMR conditions is a very important result.
This will further push the development of novel high areal density hard disk drives.
A jump in HDDs’ data density by a factor of ten and a significant reduction in wear
rate are critical to achieving more sustainable and durable magnetic data recording.
Graphene based technological developments are progressing along the right track towards
a more sustainable world.
The researcher says that this work showcases the excellent mechanical, corrosion and wear
resistance properties of graphene for ultra-high storage density magnetic media.
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.