Ultrafast imaging of electron waves in graphene

Celia Elliott

The fastest movies ever made of electron motion, created by scattering x-rays off of graphene, have shown that the interaction among its electrons is surprisingly weak.

Graphene is a single atomic layer of carbon whose unusual electronic structure makes it a candidate for a new generation of low-cost, flexible electronics. A major outstanding question is whether the electrons in graphene move independently, or if their motion is correlated by Coulomb repulsion.

Using advanced x-ray scattering techniques, physicists in Peter Abbamonte’s group at the University of Illinois at Urbana-Champaign have imaged the motion of electrons in graphene with resolutions of 0.533 Å and 10.3 attoseconds. Their results were published on November 5 in Science.

Exactly how small and how fast are these measurements? An angstrom is 1/10,000,000,000 of a meter, about the width of a hydrogen atom. And an attosecond is to a second as a second is to the age of the universe.

The researchers found that graphene screens Coulomb interactions surprisingly effectively, causing it to act like a simple, independent-electron semimetal. Their work explains several mysteries, including why freestanding graphene fails to become an insulator as predicted. The study also demonstrates a new approach to studying ultrafast dynamics, creating a new window on the most fundamental properties of materials.

The experiments were carried out at the Frederick Seitz Materials Research Laboratory at the University of Illinois and the Advanced Photon Source at Argonne National Laboratory.

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Assistant Professor Bryce Gadway of the Department of Physics at the University of Illinois Urbana-Champaign has been selected for the 2017 U.S. Air Force Young Investigator Research Program. Gadway is among 43 early-career scientists and engineers nationwide to receive this three-year award of $450,000. U.S. Air Force Young Investigators are selected based on demonstrated exceptional ability and promise for conducting basic research in scientific and engineering areas identified as strategic to the US Air Force mission.

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A company founded by a University of Illinois physics professor has raised more than $1.5 million in venture funding this year, graduated from the UI Research Park's EnterpriseWorks incubator and this week announced it was selected for a project by NASA.

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  • Outreach

Because physics has its dark mysteries too, we have appropriated Halloween! Watch our Dark Matter Day video on our YouTube channel!

Watch the short video Dark Matter and hear leading-edge scientists explain what we know about one of the greatest mysteries of our time. What could it be? How do we know it’s there? And what ingenious methods are scientists, working in different subdisciplines of physics and astronomy around the globe, using to detect dark matter?

Astrophysicist Jeff Filippini, astronomer Felipe Menanteau, experimental nuclear physicist Liang Yang, theoretical particle physicist Jessie Shelton, and experimental particle physicist Ben Hooberman provide an accessible overview of some of the most exciting scientific research that is ongoing today.

This educational outreach video was produced by the Department of Physics at the University of Illinois at Urbana Champaign, under the direction of U of I Public Affairs Video Services.