Control over topological insulator photocurrents with light polarization

Understand

Three-dimensional topological insulators represent a new quantum phase of matter with spin-polarized surface states that are protected from backscattering.

• The static electronic properties of these surface states have been comprehensively imaged by both photoemission and tunneling spectroscopies.
• Theorists have proposed that topological surface states can also exhibit novel electronic responses to light, such as topological quantum phase transitions and spin-polarized electrical currents.
• However, the effects of optically driving a topological insulator out of equilibrium have remained largely unexplored experimentally, and no photocurrents have been measured.