The discovery, which was described in the journal Nature, builds on 35 years of nanotechnology history at IBM, including their Nobel prize-winning scanning tunneling microscope (STM) that was used to build the atomic hard drive.
The scientists used a single atom of the rare earth element holmium and carefully placed it on a surface of magnesium oxide, which makes its north and south poles hold in a stable direction. The two stable magnetic orientations define the 1 and 0 of the bit.
The researchers then used a very accurate, sharp, and small, needle to pass an electrical current through the holmium atoms that flips its north and south poles, thus replicating the process of writing binary data (1s and 0s) to a traditional magnetic hard drive.
“Magnetic bits lie at the heart of hard disk drives, tape, and next-generation magnetic memory,” Christopher Lutz, IBM nanoscience researcher said in a statement. “We conducted this research to understand what happens when you shrink technology down to the most fundamental extreme—the atomic scale.”
For more insight into the project, you can check out IBM’s video given below:
For more practical illustration, researchers say a system using the tiny magnets could potentially someday store all the songs on the iTunes music library — that’s 35 million songs — on a hard drive the size of a credit card.
Future applications of nanostructures built with control over every atom could someday make data centers, computers, and other personal devices radically smaller and more powerful.
The practical development of these methods, of course, is far out in the future and could take a while to commercialize it.
So, this breakthrough could allow people to store 1,000 times more information in the same amount of space in the future applications.
Current commercially-available magnetic memory devices require approximately one million atoms to do the same.
Andreas Heinrich, newly appointed Director of the Center for Quantum Nanoscience, within the Institute of Basic Science (IBS, South Korea), led the research effort that made this discovery at IBM Almaden Research Center (USA).
This result is a breakthrough in the miniaturization of storage media and has the potential to serve as a basis for quantum computing.
Disks coated with a magnetized layer of metal allow our computers to store files in the form of bits, each with the value of either 1 or 0.
A certain direction of magnetization corresponds to the 0 bit, the other direction to the 1 bit.
While at the moment small areas of the disk, of around a million atom, correspond to each digital bit of information, this research went way beyond this and utilized the smallest amount of matter usable for this purpose: one atom.
In this study, scientists worked with a tool, called Scanning Tunneling Microscope (STM), which has a special tip that enables the user to view and move individual atoms, as well as to apply a pulse of electrical current to them.
They used this electric pulse to change the direction of magnetization of individual holmium atoms. By doing that, the team could write a memory of either 1 or 0 in a single holmium atom as well as swap the two.
A quantum sensor, designed by Heinrich’s team and currently unique worldwide, was used to read the memory stored in the holmium atom.
It consists of an iron atom placed next to the holmium atom. Using this technique, as well as another one, called tunnel magnetoresistance, the researchers could observe that holmium maintains the same magnetic state stably over several hours.
Then, when Heinrich’s team of researchers tried to use two holmium atoms instead of one, they made another surprising discovery.
Placing holmium atoms even one nanometer apart did not impact their ability to store information individually.
This came as a surprise, since it was expected that the magnetic field from one atom would impact its neighbor.
To put this scale into perspective, if a nanometer were blown up to the diameter of a typical human hair, the hair would have a diameter equivalent to the length of a school bus in comparison.
In this way, the scientists could build a two bit device with four possible types of memory: 1-1, 0-0, 1-0 and 0-1 clearly distinguished by the iron sensor.
Moore’s Law predicted that the amount of data that can be stored on a microchip would double every 18 months and indeed this happened for decades.
The last model electronic devices are always smaller and more powerful than the previous one. However, as devices becomes smaller and smaller, since atoms are so close to each other, new interfering quantum properties begin to manifest and cause problems.
The impossibility of keeping up with further miniaturization, brought experts to talk about the death of Moore’s Law.
Interestingly, holmium atoms seem to escape this fate, for still unknown reasons. “There are no quantum mechanical effects between atoms of holmium. Now we want to know why,” points out Heinrich.
Holmium atoms can be arranged very closely together, so the storage density using this single-atom technique could be very high. He continues: “We have opened up new possibilities for quantum nanoscience by controlling individual atoms precisely as we want. This research may spur innovation in commercial storage media that will expand the possibilities of miniaturizing data storage.”
Heinrich is one of the few in the world using this tool to measure and change the properties of individual atoms.
He plans to significantly expand on this research at his newly created IBS research center, located at Ewha Womans University in Seoul.