Ultrafast imaging of electron waves in graphene

Celia Elliott
11/5/2010 12:00 AM

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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Celia Elliott, Physics Illinois’ director of external affairs and special projects, has received the 2016 SPaRC Career Achievement Award, for her significant and sustained contributions throughout her career to the field of research administration at the University of Illinois at Urbana-Champaign. The award was presented by the campus’s Sponsored Programs and Research Compliance group on Friday, September 16, 2016, during the SPaRC Retreat at the I-Hotel in Urbana.
Elliott is widely recognized among the department’s faculty as the pivotal resource for all things pertaining to successful grant writing and administration.