Letter S

Miniaturized information storage in atomic-scale antiferromagnets. The binary representation of the letter ‘S’ (01010011) was stored in the Neel states of eight iron atom arrays.

After five years of work, IBM announced on Thursday that its researchers have been able to reduce from about one million to 12 the number of atoms required to create a bit of data. (video)

The breakthrough may someday allow data storage hardware manufacturers to produce products with capacities that are orders of magnitude greater than today’s hard disk and flash drives.

“Looking at this conservatively … instead of 1TB on a device you’d have 100TB to 150TB. Instead of being able to store all your songs on a drive, you’d be able to have all your videos on the device,” said Andreas Heinrich, IBM Research Staff Member and lead investigator on this project.

Today, storage devices use ferromagnetic materials where the spin of atoms are aligned or in the same direction.

The IBM researchers used an unconventional form of magnetism called antiferromagnetism, where atoms spin in opposite directions, allowing scientists to create an experimental atomic-scale magnet memory that is at least 100 times denser than today’s hard disk drives and solid-state memory chips.


The technology could also someday be applied to tape media.

While the science behind what IBM researchers accomplished is complex, the results are quite simple: They put a spin on the old adage that “opposites attract.”

Instead today’s method for magnetic storage where iron atoms are lined up with the same magnetic polarization, requiring greater distance between them, IBM created atoms with opposite magnetization, pulling them more tightly together.

“Moore’s Law is basically the drive of the industry to shrink components down little by little and then solve the engineering challenges that go along with that but keeping the basic concepts the same. The basic concepts of magnetic data storage or even transistors haven’t really changed over the past 20 years,” Heinrich said. “The ultimate end of Moore’s Law is a single atom. That’s where we come in.”

The researchers started with one iron atom and used the tip of scanning tunneling microscope to switch magnetic information in successive atoms. They worked their way up until eventually they succeeded in storing one bit of magnetic information reliably in 12 atoms. The tip of the scanning tunneling microscope was then used to switch the magnetic information in the bits from a zero to a one and back again, allowing researchers to store information.

IBM used iron atoms on copper nitrate to perform its experiments, but other materials could theoretically require even fewer atoms to store a bit of data.

The experiment was performed at low temperature: about 1 degree Kelvin, which corresponds to about -272 °C (-458 °F). The byte starts switching randomly about once a minute due to thermal energy (heat) at about 5 degrees Kelvin.

“We use low temperatures because it enables us to start from one atom and assemble bigger and bigger structures while keeping an eye on their magnetic properties. The more atoms we use to make each bit, the more stable the bits become. We anticipate that in order to make bits of this type that are stable at room temperature would require about 150 atoms per bit (rather than 12 atoms at low temperatures),” an IBM spokesman said.

The researchers then combined 96 atoms to make one byte of data, such as a letter or number. IBM then put many of the bytes together to create information. The first word they spelled using the new technique: THINK, which required five bytes of information or 480 magnetized atoms.

“The atomic scale magnetic data storage is orders of magnitude smaller than a single conventional bit,” Heinrich said.

Heinrich is quick to point out that the breakthrough is more theoretical than practical at this point; storage manufacturers aren’t going to build a storage devices that use a scanning tunneling microscope to switch bits back and forth to store data.

But the research proves storage mediums can be vastly denser than they are today.

“If you look at magnetic data storage element in a solid state device, like a spintronics device [also known as magnetoelectronics] or in a hard disk drive, you have about one million atoms in each bit,” Heinrich said. “So you have a lot of leeway from where we currently are.”

Heinrich predicted that devices using IBM’s new method of data storage would take five to 10 years to develop, but the research is critical in that it proves previous theoretical limits to data storage do not exist.

“Using iron atoms on a copper nitrite surface is probably far from being a real technology. You don’t want to build this with the tool we’re using, which is a research tool,” he said. “You want to build this cheaply for a mass environment, and that’s a huge engineering challenge.”

Antiferromagnets is not the only data storage project that IBM is working on. Last year, the company produced its first Racetrack Memory circuit, which could also lead to silicon chips with the capacity of today’s hard drives, but the durability and performance of flash drives. Henrich, however, said Racetrack technology falls somewhere between today’s storage mediums and IBM’s most recent antiferromagnets discovery.

“In the technology world, hopefully this will gather some momentum to allow them to use antiferromagnetic structures as active elements and then solve the all the technological problems around that,” Heinrich added.

Via Computer World