Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 92: Poster Session - Ultrafast Electron Dynamics at Surface and Interfaces II
O 92.5: Poster
Wednesday, March 18, 2020, 18:15–20:00, P2/1OG
Energy and momentum streaking in subcycle THz-ARPES — •Jens Güdde1, Johannes Reimann1, Suguru Ito1, Stefan Schlauderer2, Christoph Schmid2, Christoph Lange2, Rupert Huber2, and Ulrich Höfer1 — 1Fachbereich Physik, Philipps-Universität Marburg, Germany — 2Fakultät für Physik, Universität Regensburg, Germany
Recently, we have demonstrated a novel concept of subcycle THz-ARPES, which permits a direct access to carrier transport in non-trivial band structures with high time resolution [1]. This concept employs time- and Angle-Resolved Photoelectron Spectroscopy (ARPES) to observe how the carrier wave of a THz pulse accelerates Dirac fermions in the topological surface state of Bi2Te3.
Here, we will show that in addition to this acceleration within the sample, the THz electric field also leads to an energy and momentum streaking of the photoemitted electrons, the size of which depends on its polarization direction. For UV photoemission pulses that are much shorter than the period of the THz driving field, this streaking can be used for an in-situ sampling of the electric field at the sample surface, but also needs to be taken into account for a correct interpretation of the photoelectron spectra. We will discuss how the acceleration within the sample and the streaking in front of the surface both affect energy and momentum of the detected photoelectrons in a different manner, and how these contributions can be disentangled.
[1] J. Reimann et al. Nature 562, 396 (2018).