Dresden 2020 – wissenschaftliches Programm
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PLV XI: Plenarvortrag
Donnerstag, 19. März 2020, 08:30–09:15, HSZ 01
THz-ARPES band structure movies of Dirac surface currents — •Ulrich Höfer — Fachbereich Physik, Philipps Universität Marburg, Germany
Time-resolved photoelectron spectroscopy combines femtosecond pump-probe techniques with angle-resolved photoelectron spectroscopy (ARPES). New opportunities for this powerful technique arise in combination with THz excitation. As an example, I will explain how THz-ARPES can be used to measure electron transport in the Dirac surface state of a three-dimensional topological insulator in a contact-free fashion and with femtosecond time resolution. We induce electrical currents in these states with the carrier wave of strong THz transients, and we directly access their dynamics in momentum space with subcycle time resolution. As a result of spin-momentum locking, the accelerated spin-polarized electrons reach ballistic mean free paths of several hundreds of nanometers.
Subcycle THz-ARPES not only provides a way of observing carrier transport in k-space. The method may well herald a new era of time-domain investigations of new materials and phenomena. I will briefly discuss perspectives and experimental challenges of the technique.