Twelve atoms are all that's required to store a bit of computer code – a 1 or 0, according to a new discovery that probes the limit of classical data storage.
Computer hard drives on the market today use more than a million atoms to store a single bit and more than half a billion to store a byte, which is an eight-bit-long unit of code sufficient to write the letter A, for example.
The new technique uses just 96 atoms per byte, allowing for hard drives that store 100 times more information in the same amount of physical space, according the researchers behind the discovery.
"We can put the neighboring bits at the same atomic spacing that the atoms have inside the bit," Andreas Heinrich, a lead investigator in atomic storage at IBM Research in California, told me.
"So, we can really pack them right next to each other."
The storage technique is based on an unconventional form of magnetism called antiferromagnetism.
Normal magnets used in today's hard drives — and to hold your child's artwork on the refrigerator — are made of ferromagnetic materials. The spins of atoms in these magnets align with each other.
That's "good" because it provides an overall magnetic field that we can read as a bit — a 1 or 0, explained Heinrich.
"But it is bad because the magnetic field from one bit will interfere with the magnetic field from the neighboring bit and so you can't pack these bits too close together because they'll just talk to each other," he said.
Antiferromagnets, by contrast, cancel each other out, so there's no magnetic field emanating from them. That means they can be packed close together, allowing for the increased data storage density.
Atomic building blocks
Heinrich and his colleagues were led to antiferromagnets on an exploratory research quest to find out how small they could make a magnetic device and use it for classical data storage.
They used a scanning electron microscope, which allows researchers to see and manipulate atoms, to build a data storage system up one atom at a time.
Scientists know that single atoms exhibit funky quantum behaviors that require a different set of equations to describe. But where is the transition between quantum and classical behaviors?
At eight atoms, the team found, a bit was stable for a few seconds and "at 12 atoms it turns out that the classical concepts are so good that these magnetic structures hold their magnetic state for days," Heinrich said.
"We said that's good enough to call it storage."
The caveat is that this stability is found when the atoms are kept at a chilly minus 268 degrees Celsius, or 5 Kelvin. Stability at room temperature, Heinrich said, is thought possible at around 150 atoms.
The findings are reported today in the journal Science.
The finding could lead to terabyte hard drives the size of a pinhead or thumb drives that hold every movie you've ever seen, Rick Doherty an analyst with technology consulting firm Envisioneering Group told me.
Other applications may come in medical devices such as magnetic nanobots swimming in the bloodstream that can be attached and detached to tissues electronically.
"It is going to make life better, allow us to save energy, make smaller structures, and maybe one day magnetic computer logic," he said.
While transferring some of this atomic scale technology to real world gadgets may take awhile, Heinrich said the use of antiferromagnets in traditional hard drives is likely as soon as five years now.
"If you were able to use antiferromagnets instead of ferromagnets, you … could pack these things denser and therefore you could store a lot of information on your drive."
More on atomic-scale computing and storage:
- Four-atom-wide wire may herald tiny computers
- Salt — table kind — can boost hard drive storage
- Hard drives are getting bigger, better
- New technology boosts hard drive capacity