Magazine article Science News

Ghostly Electrons: Particles Flit through Atom-Thin Islands

Magazine article Science News

Ghostly Electrons: Particles Flit through Atom-Thin Islands

Article excerpt

Confine electrons within microscopically thin layers of material and weird things happen. Experiments on semiconductors in the 1980s demonstrated that to physicists (SN: 10/17/98, p. 247).

Now, two independent research teams have found that electrons imprisoned within a carbon sheet one atom thick behave in yet other odd ways, unlike anything seen in other materials. The electrons act as if they have no mass, so they zip along much faster than electrons moving through semiconductor layers do.

To properly account for the particles' behavior, scientists use equations that include aspects of Einstein's theory of relativity. The electrons act like a kind of particle known as a Dirac fermion, which shows up in particle accelerators and cosmic rays. Scientists expect it to also appear in some high-temperature superconductors, gases adjacent to neutron stars, and other exotic circumstances. The new electronic entity looks promising as a benchtop model for investigating the physics of such particles, the researchers say.

A practical payoff is possible as well. The fast electrons could enable the novel carbon sheets to serve as a new type of circuit element in electronic devices capable of operating at frequencies 1,000 times as high as today's components commonly do, says Andre K. Geim of the University of Manchester in England, who leads one of the research teams.

For decades, scientists interested in two-dimensional arrangements of electrons have built stacks of semiconductor materials--the sorts of structures ubiquitous in today's microcircuits--to confine the particles to the zone where two layers of a stack meet (SN: 12/18&25/04, p. …

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