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February 15, 2007

Quantum hall effect observed at room temperature

Quantum hall effect observed at room temperature using strong magnetic fields observations of graphene.

The quantum Hall effect was previously believed to only be observable at temperatures close to absolute zero (equal to minus 459 degrees). But when scientists at the National High Magnetic Field Laboratory in the U.S. and at the High Field Magnet Laboratory in the Netherlands put a recently developed new form of carbon called graphene in very high magnetic fields, scientists were surprised by what they saw.

"At room temperature, these electron waves are usually destroyed by the jiggling atoms and the quantum effects are destroyed," said Nobel Prize winner Horst Stormer, physics professor at Columbia University and one of the paper's authors. "Only on rare occasions does this shimmering quantum world survive to the temperature scale of us humans.

That opinion began to change, however, with the ability to create very high magnetic fields and with the discovery of graphene, a single atomic sheet of atoms about as strong as diamond. Together, these two things have allowed scientists to push this fragile quantum effect all the way to room temperature. Now there is a way to see curious and often surprising quantum effects, such as frictionless current flow and resistances as accurate as a few parts per billion, even at room temperature.

The room temperature quantum Hall effect was discovered independently in the two high field labs, in the 45-tesla Hybrid magnet in Tallahassee and in a 33-tesla resistive magnet in Nijmegen. Both research groups agreed that a common announcement on both sides of the Atlantic was the right thing to do.

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