Recent discovery reveals graphene stripes
Graphene is a material made up of a single sheet of carbon atoms one atom thick, and is found in the marks made by a graphite pencil. Graphene has remarkable physical properties and therefore has great technological potential such as in transparent electrodes for flat screen TVs, in fast energy-efficient transistors and in ultra-strong composite materials. Scientists are now devoting huge efforts to understand and control the properties of this material.
These are electronic stripes, called 'charge density waves,' on the surface of a graphitic superconductor. Credit: K. A. Rahnejat.
The LCN team donated extra electrons to a graphene surface by sliding calcium metal atoms underneath it. One would normally expect these additional electrons to spread out evenly on the graphene surface, just as oil spreads out on water. But by using a scanning tunneling microscope that can image individual atoms, the researchers have found that the extra electrons arrange themselves spontaneously into nanometer-scale stripes. This unexpected behavior demonstrates that the electrons can have a life of their own that is not connected directly to the underlying atoms. The results inspire many new directions for both science and technology. For example, they suggest a new method for manipulating and encoding information, where binary zeros and ones correspond to stripes running from north to south and running from east to west respectively.
"This discovery is another important step toward demonstrating the ubiquity of stripes, and the fact that they appear in the world's simplest host—the two-dimensional network of carbon atoms that is graphene—means that more great science and applications are not far behind," noted Jan Zaanen, professor at Leiden University.