Synopsis: Additional Peaks in Graphene’s Band Structure

Researchers observe new features in the band structure of multilayer graphene that point to enhanced electron interactions.
Synopsis figure
A. A. Zibrov et al., Phys. Rev. Lett. (2018)

Graphene is a finicky material. Defects in its hexagonal carbon lattice or stray charges in its environment can smear out attractive features in the material’s electronic band structure. These features include Dirac cones, peaks in the band structure, that are associated with graphene’s high charge mobility. The oxide-coated metal contacts—known as gates—typically used to apply an electric field to graphene also degrade these features. Now a team led by Andrea Young at the University of California in Santa Barbara has created a high-quality graphene device using graphite gates and pristine trilayer graphene flakes. The graphite gates remove inhomogeneities from the system’s electric potential that oxide-coated metal gates introduce, creating a “cleaner” device. The team observe new features in the band structures of trilayer graphene, including the emergence of three additional Dirac cones when the trilayer is subjected to a high electric field.

The team applied electric and magnetic fields to the trilayer and tracked changes in its band structure via capacitance measurements. In the absence of either field, the trilayer’s electronic band structure resembled a sum of the structures found for mono- and bilayer graphene. Increasing the strength of the electric field, the team observed a warping of the band structure, such that it developed three additional Dirac cones. Applying a magnetic field, they then found that near these Dirac cones, the number of overlapping electron energy levels—so-called Landau levels—in the device changed from two to three. The team says that these new features indicate both enhanced interactions among the electrons that lead to the emergence of new electronic states in graphene.

This research is published in Physical Review Letters.

–Katherine Wright

Katherine Wright is a Senior Editor of Physics.


More Features »


More Announcements »

Subject Areas

GrapheneCondensed Matter Physics

Previous Synopsis

Particles and Fields

More Gluons in the Pion

Read More »

Next Synopsis

Related Articles

Viewpoint: A Ranking Scheme for Mass-Transport Predictions
Condensed Matter Physics

Viewpoint: A Ranking Scheme for Mass-Transport Predictions

A new theory provides a way to compare the accuracy of different mass-transport calculations, which are widely used to evaluate the performance of materials. Read More »

Synopsis: A Laser Steers Electrons Inside Graphene

Synopsis: A Laser Steers Electrons Inside Graphene

Orthogonally polarized laser pulses produce a controllable, variable current whose direction can be reversed in less than a femtosecond. Read More »

Synopsis: Weyl Metals as Proxies for Astrophysical Dynamos

Synopsis: Weyl Metals as Proxies for Astrophysical Dynamos

Certain topological materials could be used in lab tests of the dynamo effect, thought to generate magnetic fields in stars and planets. Read More »

More Articles