By developing a data storage device composed of just 12 iron atoms, IBM researchers may have signalled the beginning of the end for traditional computer memory. In a paper published January 13 in Science, Andreas Heinrich and his team demonstrated the smallest ever information storage system, an impressive display in an industry where bits normally take up over half a billion atoms.
The atoms, arranged in a 6x2 pattern, were positioned one at a time with the tip of a powerful scanning tunneling microscope; they use a special kind of magnetism, called antiferromagnetism. PhysOrg explains,
Different from ferromagnetism, which is used in conventional hard drives, the spins of neighboring atoms within antiferromagnetic material are oppositely aligned, rendering the material magnetically neutral on a bulk level. This means that antiferromagnetic atom rows can be spaced much more closely without magnetically interfering with each other. Thus, the scientist managed to pack bits only one nanometer apart.
Although the research took place at a temperature near absolute zero, the scientists wrote that the same experiment could be done at room temperature with as few as 150 atoms.
As part of its demonstration of the antiferromagnetic storage effect, the researchers created a computer byte, or character, out of an individually placed array of 96 atoms. They then used the array to encode the I.B.M. motto “Think” by repeatedly programming the memory block to store representations of its five letters.
An atomically assembled array of 96 iron atoms containing one byte of magnetic information in antiferromagnetic states.
The scientists at IBM Research used a scanning tunneling microscope (STM) to atomically engineer a grouping of twelve antiferromagnetically coupled atoms that stored a bit of data for hours at low temperatures. Taking advantage of their inherent alternating magnetic spin directions, they demonstrated the ability to pack adjacent magnetic bits much closer together than was previously possible. This greatly increased the magnetic storage density without disrupting the state of neighboring bits.
Writing and reading a magnetic byte: 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, a corporate mantra used by IBM since 1914. The team achieved this using 96 iron atoms − one bit was stored by 12 atoms and there are eight bits in each byte.
The challenge of Moore's Law
We expect our hard drives to store more and cost less every few years. But by current conventions the technology industry is reaching the physical limits of its faithful adherence to Moore's Law, which says that the number of transistors on a microchip will approximately double every two years.
To continue to advance, new methods were needed to pack more data storage and computing capabilities into smaller spaces.