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O: Fachverband Oberflächenphysik

O 14: Ultrafast electron dynamics at surface and interfaces I

O 14.5: Vortrag

Montag, 9. März 2026, 16:15–16:30, TRE/MATH

Probing On-Chip THz Generation by Momentum Streaking in Photoelectron Emission Microscopy — •David Huber, Wolfgang Hoppe, Georg Woltersdorf, and Wolf Widdra — Martin-Luther-Universität Halle-Wittenberg

THz electromagnetic radiation provides ultrafast electric fields on the femtosecond timescale. Using THz radiation as a pump in time-resolved photoemission experiments enables sub-cycle probing of induced dynamics e.g. charge and spin currents. The momentum and energy streaking of electrons in vacuum – i.e., their acceleration due to the Coulomb force – has long been shown to reliably probe electric fields and THz radiation.

In a spintronic THz emitter, we generate a spin current through the ultrafast demagnetization of a 3 nm ferromagnetic thin film, which results in a surface charge current in an adjacent 3 nm platinum film due to the inverse spin Hall effect. Similar to dipole radiation, the charge current emits THz radiation into the vacuum. By time-resolved in-plane momentum streaking of photoemitted electrons, we probe the single-cycle THz electric field in front of the surface and deduce the electric surface current. We verify our findings using simulated THz radiation and streaking.

Keywords: Spintronic THz Emitter; THz momentum streaking; Ultrafast charge current