Wrangling Atoms to Create Rewritable Memory

Shelves of paper catalogues in the main reading room of the US Library of Congress Thomas Jefferson building. (Alex Wong/Getty Images)

I saw this article on nature.com and paused. I wouldn’t even have glanced at the article a few months ago, but that was before I began the ongoing edit of a book on parallel process coding to increase the speed of applications (I know, it rolls off the tongue, doesn’t it?).

But here was a new angle, using atoms to overcome the physical limitation of Moore’s Law to increase memory in smartphones and computers. Moore’s law famously predicts that the number of transistors people can squeeze onto memory chips will double every couple of years, but as of now, Moore’s law seems to have reached a limit: technology cannot be miniaturized indefinitely.

Researchers are trying to get around this limitation by starting small—using individual atoms—to make big gains in data-storage capacity. Now, a team has developed a 1-kilobyte rewritable data-storage device using chlorine atoms arranged on a small metal surface. According to a researchers report on 18 July in Nature Nanotechnology, if the team expanded that surface to one square centimeter, it could hold about 10 terabytes of information. This is HUGE news!

“It’s by far the largest assembly on an atomic scale that’s ever been created, and it outperforms state-of-the-art hard disk drives by orders of magnitude in data capacity,” says lead study author Sander Otte, a physicist at Delft University of Technology in the Netherlands.

Otte and his team have arranged chlorine atoms into square grids on a copper surface, and then placed those grids side-by-side, like uninterrupted terraces. Each grid contains a few empty slots, or holes. This allows the research team to move atoms around, much like sliding pieces around in a tile puzzle. Each line on a grid encodes one unit of digital information called a ‘byte.’

Otte’s team uses a scanning tunnelling microscope with a sharp needle, like the tiniest of tweezers, to probe the atoms and make them hop into adjacent spaces. One chlorine atom and one vacancy make one bit (there are 8 bits in one byte). Moving chlorine atoms in and out of vacant spots means researchers can switch between ones and zeroes, the basis for all computer code.

This pattern of atoms and vacant spaces encodes the letter ‘e’ (Courtesy TU Delft)

One of the big drawbacks of this device is that it must be kept at –196 °C: the boiling point of liquid nitrogen. This is a far cry from room temperature. But, “It’s very nice proof-of-principle work, demonstrating the first step of applying this technique of atomic manipulation to something that could lead to a functional memory device,” says Stefan Fölsch, a materials physicist at the Paul Drude Institute for Solid State Electronics in Berlin.

If researchers can find a solution or work-around for the current physical constraints and limitations to this atomic technology, they could eventually scale the technology up to larger structures and arrange their grids in three dimensions, then one could pack hundreds of terabytes—equivalent to all the information contained in the US Library of Congress—into a cube the size of a grain of salt. Further improvements could prove useful to data storage in the cloud, reducing the need for new data centers, which are currently dotting landscapes around the globe like fast-growing lichen.

But data storage is just one application. “Otte’s research gets people interested in thinking about what we want to do on an atomic scale,” says Chris Lutz, a staff scientist at IBM Research at Almaden Research Center in San Jose, California. In the long term, Otte and his colleagues’ research could pave the way to designing new materials, atom by atom.

A huge fan of nanotechnology, I hope to be around for new developments in the years to come. I KNEW that small could be dynamic!


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