New exotic material could revolutionize electronics

Jun 15, 2009
This is a surface electron band structure of bismuth telluride. Credit: Image courtesy of Yulin Chen and Z. X. Shen

Move over, silicon -- it may be time to give the Valley a new name. Physicists at the Department of Energy's (DOE) SLAC National Accelerator Laboratory and Stanford University have confirmed the existence of a type of material that could one day provide dramatically faster, more efficient computer chips.

Recently-predicted and much-sought, the material allows electrons on its surface to travel with no loss of energy at room temperatures and can be fabricated using existing semiconductor technologies. Such material could provide a leap in speeds, and even become the bedrock of an entirely new kind of computing industry based on spintronics, the next evolution of electronics.

Physicists Yulin Chen, Zhi-Xun Shen and their colleagues tested the behavior of electrons in the compound bismuth telluride. The results, published online June 11 in Science Express, show a clear signature of what is called a topological insulator, a material that enables the free flow of electrons across its surface with no loss of energy.

The discovery was the result of teamwork between theoretical and experimental physicists at the Stanford Institute for & Energy Science, a joint SLAC-Stanford institute. In recent months, SIMES theorist Shoucheng Zhang and colleagues predicted that several bismuth and antimony compounds would act as topological insulators at room-temperature. The new paper confirms that prediction in bismuth telluride. "The working style of SIMES is perfect," Chen said. "Theorists, experimentalists, and sample growers can collaborate in a broad sense."

The experimenters examined bismuth telluride samples using X-rays from the Stanford Synchrotron Radiation Lightsource at SLAC and the Advanced Light Source at Lawrence Berkeley National Laboratory. When Chen and his colleagues investigated the electrons' behavior, they saw the clear signature of a topological insulator. Not only that, the group discovered that the reality of bismuth telluride was even better than theory.

"The theorists were very close," Chen said, "but there was a quantitative difference." The experiments showed that bismuth telluride could tolerate even higher temperatures than theorists had predicted. "This means that the material is closer to application than we thought," Chen said.

This magic is possible thanks to surprisingly well-behaved electrons. The of each electron is aligned with the electron's motion—a phenomenon called the quantum spin Hall effect. This alignment is a key component in creating spintronics devices, new kinds of devices that go beyond standard electronics. "When you hit something, there's usually scattering, some possibility of bouncing back," explained theorist Xiaoliang Qi. "But the quantum spin Hall effect means that you can't reflect to exactly the reverse path." As a dramatic consequence, electrons flow without resistance. Put a voltage on a topological insulator, and this special spin current will flow without heating the material or dissipating.

Topological insulators aren't conventional superconductors nor fodder for super-efficient power lines, as they can only carry small currents, but they could pave the way for a paradigm shift in microchip development. "This could lead to new applications of spintronics, or using the electron spin to carry information," Qi said. "Whether or not it can build better wires, I'm optimistic it can lead to new devices, transistors, and spintronics devices."

Fortunately for real-world applications, bismuth telluride is fairly simple to grow and work with. Chen said, "It's a three-dimensional material, so it's easy to fabricate with the current mature semiconductor technology. It's also easy to dope—you can tune the properties relatively easily."

"This is already a very exciting thing," he said, adding that the material "could let us make a device with new operating principles."

More information:

Source: SLAC National Accelerator Laboratory

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User comments : 10

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4.5 / 5 (2) Jun 15, 2009
wont see this again for another 10 years, as all great discoveries go...
4 / 5 (4) Jun 15, 2009
Forget 10 years, more like 30 years away

Thankfully, other technologies are closer to reality

- like toshiba's new 14nm process, expect that in
4-6 years

- Graphene chips in 10-12 years

- Quantum computing, expect that to never reach

1 / 5 (3) Jun 15, 2009
too much money is invested in 'silicon' - thus, any new technology must be compatible with Si-based technology to 'survive'
2.6 / 5 (5) Jun 15, 2009
These technologies will disappear into the military-industrial complex (MIC) and in some years, their technology will seem like extraterrestrial technology, or something out of Star Trek, when compared to our consumer-level "pedestrian" technology. Rule by technological superiority - bad news for politicians - and for us as well . . .

The MIC will discover that profit by selling to consumers is eclipsed by the tremendous power to be gained by controlling availability of information and technology. Who wants to make mere billions when you can own the world itself?
3 / 5 (2) Jun 15, 2009
Ferroelectric Bismuth Tellurium material around
for many years.

Of all the revolutionary, uniquie, exotic, never seen before claims. I would say very few are true.
2.3 / 5 (3) Jun 15, 2009
Anyone know why it cant carry a bigger amounts of current?
1 / 5 (1) Jun 15, 2009
Chen said, "It's a three-dimensional material, so it's easy to fabricate with the current mature semiconductor technology. It's also easy to dope%u2014you can tune the properties relatively easily."

looks like it will be easy to fabricate with existing technology...
not rated yet Jun 16, 2009
curious how clean the surface would have to be...I suspect pretty pristine.
2.3 / 5 (3) Jun 17, 2009
5 / 5 (3) Jun 20, 2009
Oops, now you tell me! I just ordered some bismuth telluride toppings with my combination pizza. Now I have a free flow of electrons on my mustache. Oh well, anyhoo, I'm charged up for the day. So far, no loss of energy.