SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 37: Poster: Ultrafast Electron Dynamics at Surface and Interfaces II

O 37.11: Poster

Dienstag, 28. März 2023, 18:00–20:00, P2/EG

Combining THz-ARPES and THz-HHG to study electrical currents at buried interfaces of topological insulators — •Tim Bergmeier, Suguru Ito, Jens Güdde, and Ulrich Höfer — Fachbereich Physik, Philipps-UniversitätMarburg, Germany

Angle-resolved photoemission spectroscopy (ARPES) combined with terahertz (THz) excitation has shown to provide a subcycle-resolved momentum space view of lightwave-driven Dirac currents in the surface band of topological insulators [1]. At high electric field strength, these currents have shown to give rise to a unique type of efficient high-harmonic generation (HHG) that reflects the unusual transport properties of the Dirac electrons [2]. As a pure optical technique, THz-HHG is able to access also deeply buried interfaces, but lacks band structure information.

Here, we present an experimental setup which combines both techniques in order to study first the impact of thin protection layers on the current transport in a topologically protected band. The correlation of the time-resolved band structure information provided by THz-ARPES with the properties of THz-HHG will then allow us to apply the latter for thick layers as will be required for device applications. The setup includes the generation of THz-pulses with field strengths up to 10 MV/cm over a frequency range of 12-80 THz, and of ultrashort 400-nm probe pulses for two-photon photoemission with subcycle time resolution at a repetition rate of 200 kHz.

[1] J. Reimann et al., Nature 562, 396 (2018).
[2] C. P. Schmid et al., Nature 593, 385 (2021).