New Study Confirms Exotic Electric Properties of Graphene
This illustration shows the tip of a scanning tunneling microscope approaching an undulating sheet of perfect graphene. The exotic substance is 10 times stronger than steel and conducts electricity better than any known material at room temperature. Both physicists and nanoscientists are studying graphene and exploring its potential applications. (Image Source: Vanderbilt Univeristy; Image Credit: Calvin Davidson, British Carbon Group)
First, it was the soccer-ball-shaped molecules dubbed buckyballs. Then it was the cylindrically shaped nanotubes. Now there is graphene: a remarkably flat molecule made of carbon atoms arranged in hexagonal rings much like molecular chicken wire. It is 10 times stronger than steel and conducts electricity better than any other known material at room temperature. These and graphene’s other exotic properties have attracted the interest of physicists, who want to study them, and nanotechnologists, who want to exploit them to make novel electrical and mechanical devices. Although graphene is the first truly two-dimensional crystalline material that has been discovered, over the years scientists have put considerable thought into how two-dimensional gases and solids should behave. They have also succeeded in creating a close approximation to a two-dimensional electron gas by bonding two slightly different semiconductors together. Electrons are confined to the interface between the two and their motions are restrained to two dimensions. When such a system is cooled down to less than one degree above absolute zero and a strong magnetic field is applied, then the fractional quantum Hall effect appears. Since scientists figured out how to make graphene five years ago, they have been trying to get it to exhibit this effect with only marginal success. The best way to understand it is to think of the electrons in graphene as a forming a (very thin) sea of charge. When the magnetic field is applied, it generates whirlpools in the electron fluid. Because electrons carry a negative charge, these vortices have a positive charge.
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