Scientists from IBM Research have successfully demonstrated the ability to store information in as few as 12 magnetic atoms. This is significantly less than today’s disk drives, which use about one million atoms to store a single bit of information. The ability to manipulate matter by its most basic components – atom by atom – could lead to the vital understanding necessary to build smaller, faster and more energy-efficient devices.

If you’re impressed with how much data can be stored on your portable hard drive, well … that’s nothing. Scientists have now created a functioning magnetic data storage unit that measures just 4 by 16 nanometers, uses 12 atoms per bit, and can store an entire byte (8 bits) on as little as 96 atoms – by contrast, a regular hard drive requires hundreds of crore atoms for each byte. It was created by a team of scientists from IBM and the German Center for Free-Electron Laser Science (CFEL).

The storage unit was created one atom at a time, using a scanning tunneling microscope. Iron atoms were arranged in rows of six, these rows then grouped into pairs, each pair capable of storing one bit of information – a byte would require eight pairs of rows.

Each pair can be set to one of two possible magnetic configurations, which serve as the equivalent of a 1 or 0. The most basic piece of information that a computer understands is a bit. Much like a light that can be switched on or off, a bit can have only one of two values: “1” or “0”. Until now, it was unknown how many atoms it would take to build a reliable magnetic memory bit.

With properties similar to those of magnets on a refrigerator, ferromagnets use a magnetic interaction between its constituent atoms that align all their spins – the origin of the atoms’ magnetism – in a single direction. Ferromagnets have worked well for magnetic data storage but a major obstacle for miniaturizing this down to atomic dimensions is the interaction of neighboring bits with each other. The magnetization of one magnetic bit can strongly affect that of its neighbor as a result of its magnetic field. Harnessing magnetic bits at the atomic scale to hold information or perform useful computing operations requires precise control of the interactions between the bits.

While conventional hard drives utilize a type of magnetism known as ferromagnetism, the atom-scale device uses its opposite, antiferromagnetism. In antiferromagnetic material, the spins of neighboring atoms are oppositely aligned, which keeps them from magnetically interfering with one another. The upshot is that the paired rows of atoms were able to be packed just one nanometer apart from one another, which wouldn’t otherwise have been possible.

Before you start expecting to find antiferromagnetic rows of atoms in your smartphone, however, a little work still needs to be done. Presently, the material must be kept at a temperature of  -268ºC . The IBM/CFEL researchers are confident, however, that subsequent arrays of 200 atoms could be stable at room temperature.

It was found that 12 atoms was the minimum number that could be used for storing each bit, before quantum effects set in and distorted the information. CFEL’s Sebastian Loth said “We can now use this ability to investigate how quantum mechanics kicks in. What separates quantum magnets from classical magnets? How does a magnet behave at the frontier between both worlds? These are exciting questions that soon could be answered.”

Loth was the lead author of a paper on the research, which was published 16th January 2012 in the journal Science.

We feel while silicon transistor technology has become cheaper, denser and more efficient, fundamental physical limitations suggest this path of conventional scaling is unsustainable. Alternative approaches are needed to continue the rapid pace of computing innovation.

By taking a novel approach and beginning at the smallest unit of data storage, the atom, scientists demonstrated magnetic storage that is at least 100 times denser than today’s hard disk drives and solid state memory chips. Future applications of nanostructures built one atom at a time, and that apply an unconventional form of magnetism called antiferromagnetism, could allow people and businesses to store 100 times more information in the same space.

This image shows a magnetic byte imaged 5 times in different magnetic states to store the ASCII code for each letter of the word THINK,The team achieved this using 96 iron atoms − one bit was stored by 12 atoms and there are eight bits in each byte

Source : IBM press release.

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