The material graphene can be used to pack far more data in hard disk drives compared to current methods, researchers at Cambridge University found in a recent study. It’s one of several new technologies that could make it possible to stuff more data in hard disk drives as demand grows for storage. “New applications both fuel and demand massive data sets,” John Morris, the chief technology officer of hard-drive maker Seagate Technology, said in an email interview. “That is why hard drives are getting more spacious. Whatever you send to the cloud—your pictures, videos, personal and business documents—resides on higher and higher-capacity hard drives.”
Putting More in Less
Hard disk drives (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 increasingly 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, mainly because they are relatively inexpensive to produce and purchase. HDDs contain two major components: platters and a head. Data are written on the platters using a magnetic head, which races above them as they spin. The space between head and platter continually is 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, researchers say that graphene, which is a single layer of atoms arranged in a two-dimensional honeycomb lattice, lets them increase the density. The Cambridge researchers replaced commercial COCs with one to four graphene layers 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 corrosion protection, low friction, wear resistance, hardness, lubricant compatibility, and surface smoothness. Graphene enables a two-fold reduction in friction and provides better corrosion and wear than state-of-the-art solutions, the researchers claim. One single graphene layer reduces corrosion by 2.5 times. The Cambridge scientists transferred graphene onto hard disks made of iron-platinum as the magnetic recording layer and tested Heat-Assisted Magnetic Recording (HAMR). This new technology enables an increase in storage density by heating the recording layer to high temperatures. Current COCs don’t perform at these high temperatures, but graphene does. Graphene, combined with HAMR, can outperform current HDDs, providing an unprecedented data density higher than 10 terabytes per square inch, the researchers say. “Demonstrating that graphene can serve as a protective coating for conventional hard disk drives and that it is able to withstand HAMR conditions is a very important result,” Anna Ott from the Cambridge Graphene Centre, one of the co-authors of this study, said in a news release. “This will further push the development of novel high areal density hard disk drives.”
DNA for Storage?
Graphene isn’t the only game in town when it comes to innovations in data storage. Scientists are exploring the possibility that DNA could be used to store information like movies and music. DNA storage technology already exists, but it never has been transformed into a valuable product for consumers. That could change thanks to researchers at Los Alamos National Laboratory, who recently developed software, the Adaptive DNA Storage Codex (ADS Codex), which translates data files from the binary language of zeroes and ones that computers understand into the code biology understands. “DNA storage could disrupt the way we think about archival storage because the data retention is so long and the data density so high,” Bradley Settlemyer, a researcher at Los Alamos, said in a news release. “You could store all of YouTube in your refrigerator instead of in acres and acres of data centers.”
