Electron interactions in graphene

Electron interactions in graphene
Through the use of infrared, a team of researchers has conducted work in a custom-built container cooled to only a few degrees above absolute zero.

Electrons in graphene move at the speed of light and behave as though they have no mass. Scientists at the University of Washington, USA, have now established a way to view electron interactions in graphene.

Through the use of infrared, a team of researchers, led by Erik Henriksen, assistant professor at the university’s physics department, has conducted work in a custom-built container cooled to only a few degrees above absolute zero which enables them to view electron interactions in graphene.

The team have used a small shaving of graphene placed between two baron-nitride crystals, then placed this on top of a silicon wafer approximately 16 microns long – all together, the materials are less than one-sixth the size of human hair.

Henriksen said: “Here, we have constructed a system that narrowly focuses infrared light down to the sample, which is inside a large magnet and at very low temperature.” He added: “It allows us to literally shine a flashlight on it and explore its electronic properties by seeing which colours of light are absorbed.”

Material science

Graphene’s potential has produced much interest within the material science research community because of its potential applications in:

  • Batteries;
  • Solar energy cells; and
  • Touch screens, and more.

However, physicists are now interested in graphene because of its electron structure and electron interactions, where its electrons behave like relativistic particles. Under normal circumstances, electrons repel each other, and researchers have been looking into how this behaviours changes when the electrons seem to have no mass.

It has been possible for scientists to track the movements of charged particles with Landau levels, by gathering simultaneous measurements of optical and electronic properties in the presence of a high magnetic field.

Henriksen said: “A strong magnetic field provides a kind of glue to their motion—it slows them down in some ways,

“You would think it would be a very difficult system to look at. But sometimes, at very specific ranges of the magnetic field strength and the interaction strength, you’ll find that, all of a sudden, the system simplifies enormously.”

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