Ultrafast photocurrents at the surface of the three-dimensional topological insulator Bi 2 Se 3 - Archive ouverte HAL Access content directly
Journal Articles Nature Communications Year : 2016

Ultrafast photocurrents at the surface of the three-dimensional topological insulator Bi 2 Se 3

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 (B10 fs). Here, we excite and measure photocurrents in the model topological insulator Bi 2 Se 3 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 contrast, photon-helicity-dependent photocurrents are found to be orders of magnitude smaller than expected from generation scenarios based on asymmetric depopulation of the Dirac cone. Our findings are of direct relevance for broadband optoelectronic devices based on topological-insulator surface currents.
Fichier principal
Vignette du fichier
ncomms13259.pdf (602.81 Ko) Télécharger le fichier
Origin : Publisher files allowed on an open archive
Loading...

Dates and versions

hal-01445495 , version 1 (24-01-2017)

Identifiers

Cite

Lukas Braun, Gregor Mussler, Andrzej Hruban, Marcin Konczykowski, Thomas Schumann, et al.. Ultrafast photocurrents at the surface of the three-dimensional topological insulator Bi 2 Se 3. Nature Communications, 2016, 7, pp.13259. ⟨10.1038/ncomms13259⟩. ⟨hal-01445495⟩
231 View
323 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More