Synopsis: Liquid at the Edge of Graphene

Transport properties at the edges of topological states of matter may be more readily observed in graphene compared to other 2D systems.
Synopsis figure
Z.-X. Hu et al., Phys. Rev. Lett. (2011)

In condensed matter systems, topology often gives rise to gapless excitations at the edge (in 2D) or the surface (in 3D). Such excitations in the 2D fractional quantum Hall state should manifest in the edge behaving as a Luttinger liquid, in which tunneling is determined by a universal power law related to an attribute—the filling factor—of the magnetic flux through, and the number of electrons in, the 2D state.

However, no such behavior has yet been observed at the edges of 2D semiconductor heterostructures, the most-studied quantum Hall systems. Theorists say that in these systems the conflicting interplay between the confinement potential, attracting each electron towards the center, and the Coulomb force, pushing them apart from each other, modifies the edge itself. This process—edge reconstruction—disturbs the universal Luttinger liquid picture in the experimentally accessible distance scales.

In a paper in Physical Review Letters, Zi-Xiang Hu, at Princeton University, and his colleagues tell us that we may, after all, be able to see chiral Luttinger behavior in another system in which fractional quantum Hall effect has been observed—graphene. In graphene, electrons are confined by metallic gates that are placed a specific distance away. By contrast, in semiconductors, electrons are confined by dopants. This one difference should make graphene less susceptible to edge reconstruction and reveal the fractional quantum Hall state. The authors say that experimentalists should therefore finally see the elusive universal edge behavior in the experimentally accessible state with filling factor 1/3. – Sami Mitra


Announcements

More Announcements »

Subject Areas

NanophysicsGraphene

Previous Synopsis

Next Synopsis

Quantum Information

The Bound and the Free

Read More »

Related Articles

Focus: Atom-Scale Ohmmeter
Nanophysics

Focus: Atom-Scale Ohmmeter

A highly stable scanning tunneling microscope measures the electrical properties of a metal on a scale smaller than individual atoms. Read More »

Viewpoint: An Inside View of Magnetic Skyrmions
Magnetism

Viewpoint: An Inside View of Magnetic Skyrmions

Atomic-scale imaging reveals the shape and size of a technologically interesting magnetic quasiparticle. Read More »

Focus: Voltage Fluctuations Converted to Electricity
Mesoscopics

Focus: Voltage Fluctuations Converted to Electricity

In a step toward the conversion of excess heat into electric current, researchers demonstrate a device that generates current in response to voltage fluctuations that mimic heat. Read More »

More Articles