"Working with one of the purest semiconductor materials ever made, they discovered the quasi-three-dimensional electron crystal in a device cooled at ultra-low temperatures roughly 100 times colder than intergalactic space. The material was then exposed to the most powerful continuous magnetic fields generated on Earth. Their results were published in the October issue of the journal Nature Physics.
Two-dimensional electron crystals were discovered in the laboratory in the 1990s, and were predicted as far back as 1934 by renowned Hungarian physicist Eugene Wigner.
"Picture a sandwich, and the ham in the middle is your electrons," explained Dr. Guillaume Gervais, director of McGill's Ultra-Low Temperature Condensed Matter Experiment Lab. "In a 2D electron crystal, the electrons are squeezed between two materials and they're very two dimensional. They can move on a plane, like billiard balls on a pool table, but there's no up and down motion. There's a thickness, but they're stuck."
Until an accidental discovery during one of Gervais's earliest ultra-low temperature experiments in 2005, however, no one predicted the existence of quasi-three-dimensional electron crystals.
"We decided to tweak the two-dimensionality by applying a very large magnetic field, using the largest magnet in the world at the Magnet Lab in Florida," he said. "You only have access to it for about five days a year, and on the third day, something totally unexpected popped."
Gervais's "pop" was the startling transformation of a two-dimensional electron system inside the semiconducting material into a quasi-three-dimensional system, something existing theory did not predict.
"It's actually not quite 3-D, it's an in-between state, a totally new phenomenon," he said. "This is the kind of thing the theoreticians love. Now they're scratching their heads and trying to fine-tune their models."
The importance of this discovery to micro-electronics and computing could be profound."
