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Images of relativistic electrons trapped in graphene quantum dots have been taken by physicists in the US and Japan. The ability to confine and control electrons in such a way could play an important role in developing graphene-based nanoscale devices and could also provide a better understanding of these exotic Dirac fermions.

 

Relativistic electrons in graphene

 

Graphene is a honeycomb lattice of carbon atoms just one atom thick that was first isolated in 2004. It has a number of unique electronic properties, many of which come from the fact that it is a semiconductor with a zero-energy gap between its valence and conduction bands. Near where the two bands meet, the relationship between the energy and momentum of charge carriers (electrons and holes) in the material is described by the Dirac equation and resembles that of a photon. These bands, called Dirac cones, enable these charge carriers to travel through graphene at extremely high speeds approaching that of light. This extremely high mobility means that graphene-based electronic devices such as transistors could be faster than any that exist today.