Ultrafast photocurrents at the surface of the three-dimensional topological insulator Bi₂Se₃.

ABSTRACT: Three-dimensional topological insulators are fascinating materials with insulating bulk yet metallic surfaces that host highly mobile charge carriers with locked spin and momentum. Remarkably, surface currents with tunable direction and magnitude can be launched with tailored light beams. To better understand the underlying mechanisms, the current dynamics need to be resolved on the timescale of elementary scattering events (∼10 fs). Here, we excite and measure photocurrents in the model topological insulator Bi₂Se₃ with a time resolution of 20 fs by sampling the concomitantly emitted broadband terahertz (THz) electromagnetic field from 0.3 to 40 THz. Strikingly, the surface current response is dominated by an ultrafast charge transfer along the Se-Bi bonds. In contra

SUBMITTER: Braun L 

PROVIDER: S-EPMC5095513 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature