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Mar. 09, 2010

Electrons On The Brink

by Shelley DuBois

Click to enlarge images

Nanoscientists often work with materials too small to see. So when they do visualize their materials, it’s a notable scientific discovery.

That happened recently, when nanoscientist Ali Yazdani and his colleagues were able to map the position of electrons in a material on the verge of becoming a conductor.

A conductor is something that allows electricity to pass through it. Metals are famously conductive–metallic materials allow electricity to pass through them. Non-conducting materials don’t.

To figure out the transition between the two kinds of materials, Yazdani needed to change a material that doesn’t conduct electricity into one that does. To do that, he and other members of his lab at Princeton University added magnetic atoms to their non-conducting material. This addition made the material more conductive. It also made the material more and more like a metal. And, because they added magnetic atoms, it made the material more and more like a magnet. Then, and this is why the finding was published in the February issue of Science, the researchers imaged the material on the verge of that change.

The magnet part is important. Tiny magnets are inside almost every piece of electronic equipment used today. Researchers are trying to make magnets even smaller, and equip them with an on/off switch. This would allow scientists to better use magnetism in technology–and most likely make faster computers.

People have guessed what electrons would do at the moment they change from one kind of material to another, but no one has really seen it. Until now.

Here is a video, showing an image about 300-400 atoms wide, of electrons moving in a non-magnetic material that can’t conduct electricity. The clip ends just as the material is about to change into a magnetic conductor:

Practical applications may be a ways off, but the ability to actually see this change is a big step.

“Being able to visualize it, it’s very rewarding,” says Yazdani. “To some extent, seeing is believing. And that’s what we have done.”

[Image Credit: Roushan/Yazdani, Princeton]
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About Shelley DuBois

The views expressed are those of the author and are not necessarily those of Science Friday.

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