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McGill discovers a new state of matter

by Archives October 28, 2008

A McGill University researcher has discovered a new state of matter inside semi-conductors, which he said may lead the way towards a new era of electronic devices.
Dr. Guillaume Gervais, director of McGill’s Ultra-Low Temperature Condensed Matter Experiment Lab, first observed the crystals, which are not fully three dimensional in 2005 using the largest magnet in the world at the National High Magnetic Field Laboratory in Florida.
Gervais’s discovery, the Wigner crystal, was first hypothesized by Hungarian physicist Eugene Wigner in 1934. But it has never been observed before.
The crystals only exist on the quantum, or sub-atomic, level. They are neither two or three dimensional but somewhere in between.
While most people are familiar with the three states of matter: solid, liquid and gas. But for electrons inside a transistor, there are other states, known as “phases.”
“Some phases are thought to be like a gas, some other phases are just like a liquid and in some cases they form crystals. Now we think we have found a new type of such crystals, a new phase we were not aware of,” said Gervais.
According to Gervais, states of matter are different from each other “in the sense that the collective properties that emerge from that phase have nothing to do with the constituents.”
For example, water and ice have the same molecules. Water molecules can be frozen to form a solid. Collectively the particles have different properties.
The same idea applies with electrons. “An electron cannot split itself up, but sometimes, collectively the electron will act as if it were only a fraction of itself. It’s like the electron splits itself.”
Gervais said there are no direct applications for his findings, yet. And while he has some doubts they will lead to anything concrete, there is the possibility that researchers will build on his discovery to improve electronics.
Electronic devices now rely on chips that are cluttered with growing amounts of transistors to increase their capacities. They follow a well-known trend call Moore’s law. Physicist Gordon Moore predicted transistors on a chip will approximately double in number every two years, due to better technology and cheaper production. Moore’s Law has so far held true, more than 43 years after the publication of his first paper on the subject.
“This is classical physics, transistors are following this law and they’re getting smaller and smaller. But as they get smaller, they’re reaching quantum physics,” said Gervais. “It’s going to get really hard to scale things down if you don’t understand how that cross-over works.”
Gervais found the crystals by inducing a magnetic field through a semi-conductor made of pure Gallium Arsenide (GaAs) and Aluminum Gallium Arsenide (AlGaAs), a material used in cellphones to amplify high frequency signals. The experiment was performed at temperatures 100 times colder than in outer space.

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