Nature publication on Time-Resolved ARPES on Bismuth Telluride

Recently an article has been published by Reimann et al. in Nature (Vol. 562 (2018) 396; https://doi.org/10.1038/s41586-018-0544-x) with the title "Subcycle observation of lightwave-driven Dirac currents in a topological surface band". 

Topological insulators are a promising class of materials, from which Bi₂Te₃ is always named as one of the hottest candidates to find applications in novel micro- and nanoelectronic devices. The dynamics of the charge carriers in such materials is cutting edge research. The work published here describes the effect of THz fields on the velocity of Dirac fermions and the resulting redistribution observed on the band occupation of a topological insulator. In this THz excitation experiment, a THz carrier wave is used to accelerate the Dirac fermions close to the Dirac point of the Bi₂Te₃ surface state and resulting in a shifted electron occupation in momentum space around the Fermi level. The authors incorporate a pretty unique technique where THz streaking is used. The characteristics of the THz carrier wave and the probing UV laser pulse allow to monitor the electric field close to the surface.