Synopsis: A bumpy road

Analog of gravitational lensing on the surface of a topological insulator.
Synopsis figure
Credit: Adapted from J. P. Dahlhaus et al., Phys. Rev. B (2010)

Electron scattering in solids is normally associated with impurities, defects, lattice vibrations, and electron-electron Coulomb scattering. Now, in an article published in Physical Review B, Jan Dahlhaus and collaborators from the Instituut-Lorentz at the University of Leiden in the Netherlands show that for surface electrons on a topological insulator, electron scattering can be dominated by a completely different mechanism: geodesic scattering. Geodesics are the generalization of straight lines in curved space. In general relativity, gravitational fields curve four-dimensional spacetime, and particle motion follows geodesic lines shaped by gravity. Strong enough fields cause the phenomenon known as gravitational lensing, an observable deflection of massless particles such as photons.

The surface electrons of a topological insulator behave as massless particles and are constrained to move in a two-dimensional curved space. The curvature is caused by random surface deformations that appear naturally during the growth of the material. Such a bump on the surface acts like a gravitational lens for surface electrons, resulting in trajectories that are analogous to geodesic motion. Considering that due to the special nature of topological insulators these surface electrons are protected from the ubiquitous impurity backscattering, this article likely reveals a previously unsuspected and important contribution to the resistivity on the surface of these materials. – Athanasios Chantis


Announcements

More Announcements »

Subject Areas

Semiconductor Physics

Previous Synopsis

Quantum Information

Treasure hunt

Read More »

Next Synopsis

Related Articles

Synopsis: Valley of the Dichalcogenides
Semiconductor Physics

Synopsis: Valley of the Dichalcogenides

A magnetic field can be used to change the “valley” states that emerge in certain semiconductors. Read More »

Viewpoint: Chasing the Exciton Condensate
Semiconductor Physics

Viewpoint: Chasing the Exciton Condensate

Unusual interactions between charges have been observed in two closely separated graphene bilayers, a promising system in which to create a condensate of electron-hole pairs. Read More »

Viewpoint: Precise Layering of Organic Semiconductors
Semiconductor Physics

Viewpoint: Precise Layering of Organic Semiconductors

Researchers have fabricated high-quality organic semiconductors only a few molecular layers thick, revealing how the crystal structure affects the electronic properties. Read More »

More Articles