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HL: Fachverband Halbleiterphysik
HL 52: THz and MIR Physics in Semiconductors
HL 52.1: Vortrag
Freitag, 13. März 2026, 09:30–09:45, POT/0006
Probing Terahertz Emission and Structural Dynamics in Quasi-two-dimensional NbOI2 — •Daniel Geyer1, Rieke von Seggern1, Soufiane El-Kabil1, Zouchen Fu3, and Sascha Schäfer1,2 — 1Department of Physics, University of Regensburg, Germany — 2Regensburg Center for Ultrafast Nanoscopy (RUN), Germany — 3Nankai University, Tianjin, China
Optically induced processes in matter, captured via time-resolved imaging methodologies, uncover a variety of transient phenomena evolving on ultrafast time scales. Layered ferroelectric niobium oxide dihalides NbOX2 (X=I, Cl, Br) have garnered significant interest in this context, as they combine pronounced optical nonlinearities [1,2] with a ferroelectric order parameter that can be controlled via optical stimuli [3]. In this work, we investigate the NbOI2 compound as a material platform in which both regimes of ultrafast light-matter interaction can be accessed within different experimental approaches.
At first, we explore thin NbOI2 flakes as promising stackable terahertz (THz) emitters. We demonstrate broadband THz generation via nonlinear optical rectification, characterized using a time-domain THz emission spectroscopy setup.
Secondly, we discuss the photoinduced evolution of the material’s ferroelectric polarization, employing time-resolved electron diffraction in an ultrafast transmission electron microscope (UTEM).
[1] Guo et. al., Nature 613, 53-59 (2023)
[2] Chen et. al., Adv. Mater. 36, 2400858 (2024)
[3] Wang et. al., Nat. Comm. 16, 8132 (2025)
Keywords: NbOI2; Layered Materials; Time-domain Terahertz Spectroscopy (THz-TDS); Ultrafast Transmission Electron Microscopy (UTEM); Ferroelectricity