IBM measures force that moves atoms

Breakthrough comes after years of atomic research

Hitting a major milestone in nanotechnology, IBM researchers have figured out how to measure the amount of force needed to move an atom.

And that information could enable scientists to more easily — and quickly — develop nanoscale devices such as atomic-level storage and computer chips.

"IBM has been involved in atomic manipulation for 20 years," says Andreas Heinrich, a researcher and project leader at IBM. "What we have now is a way to quantify why we can move certain things, because now we know the forces involved. It's going from a trial-and-error stage to a more systematic way of doing things. It will be easier to build stuff once you have this knowledge."

Heinrich says that in 1989, IBM Fellow Don Eigler showed off the ability to manipulate individual atoms with atomic-scale precision. Nearly 20 years later, Heinrich and Markus Ternes, a post-doctoral scientist at IBM, worked with scientists at the University of Regensburg to devise a way to calculate the force needed to manipulate those individual atoms.

Understanding the force required to move an atom is key to nanotechnology, according to Ternes. He says it's like engineers figuring out how to build a bridge over a large river. They both need to understand the strength of the different materials. How much force would it take to make a piece of metal bend? How much force would it take to move a cobalt atom over a copper surface? They're similar questions that all need to be answered in order to build a bridge or a nanoscale storage device.

"It's increased our understanding of how nature works," says Ternes. "If you want to construct something, you have to know what the maximum load [is that] you can put on something before it breaks. Interactions and how easily things can move is important if you want to start talking about construction on a nanoscale."

To make the microscopic measurements, the scientists modified a scanning tunneling microscope, which is normally used to view images as small as single atoms. By mounting a needle on the microscope, the scientists can measure the motion of the needle when it moves the atom.

With this device, Ternes said they've discovered that it takes 210 piconewtons to move a cobalt atom over a platinum surface, but it takes 17 piconewtons to move a cobalt atom over a copper surface. Named after Sir Isaac Newton, a piconewton is about the force needed to hold a glass of wine in your hand, according to Ternes. To move that one cobalt atom, it would take about a millionth of a millionth of the force needed to hold that glass of wine.

Now that it's possible make these kinds of measurements, Heinrich says, IBM plans to moving forward with its work to store data on just a few atoms.

"We have been able to shrink the silicon on our chips down. That's been the great facilitator to get faster computers and more data storage, but we all know that's not going to go on forever," he says. "There will be a break at some point. What we do in our lab is take the opposite approach and start with the smallest thing — single atoms — and build data storage devices one atom at a time. This particular work will allow us to know what we can build and why we can build those things."

Their new measurement capabilities also will allow researchers to shrink the size of the transistors that are used in computer chips. Shrinking transistors cuts power requirements, boosts speed and requires less power. Some researchers consider the transistor to be the single most important invention of the 20th century.

Analysts expect the transistor to continue to drive digital products forward into the future. Intel's latest 45nm Penryn processor holds 820 million transistors. Risto Puhakka, president of VLSI Research, says he expects that within 10 to 15 years, semiconductor companies will be squeezing 10-15 billion onto a single chip.

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