Regensburg 2025 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 63: Focus Session: Nanoscale Light-matter Interaction II
HL 63.5: Vortrag
Freitag, 21. März 2025, 13:00–13:15, H14
Unraveling ultrafast exciton dynamics in a monolayer of the magnetic semiconductor CrSBr — •Jakob Schlosser1, Christian Meineke1, Martin Zizlsperger1, Marlene Liebich1, Niloufar Nilforoushan1, Kseniia Mosina2, Sophia Terres3, Alexey Chernikov3, Zdenek Sofer2, Markus A. Huber1, Matthias Florian4, Mack Kira4, Florian Dirnberger3, and Rupert Huber1 — 1University of Regensburg, Regensburg — 2University of Chemistry and Technology Prague, Prague — 3Dresden University of Technology, Dresden — 4University of Michigan, Ann Arbor
Among van der Waals semiconductors, CrSBr stands out as both its bulk and monolayer forms host tightly bound, quasi-1D excitons in a magnetic environment. Despite the strong attention these quasiparticles have attracted, their lifetimes remained unknown. Terahertz spectroscopy can directly probe the dynamics of all electron-hole pairs, independently of interband selection rules. Yet the corresponding far-field foci substantially exceed the lateral sample dimensions. Here, we combine terahertz polarization spectroscopy with near-field microscopy to study the dynamics of bound and unbound electron-hole pairs in bulk CrSBr and extract the nonequilibrium dielectric function of the monolayer in a model-free manner. Interestingly, the femtosecond decay of paramagnetic excitons in monolayer CrSBr is found to be 30 times shorter than the determined lifetime in bulk material. Our results mark the first direct access to the ultrafast dielectric response of quasi-1D excitons in CrSBr, to advance the development of quantum devices based on ultrathin van der Waals magnets.
Keywords: atomically thin solids; van der Waals magnets; anisotropic excitons; ultrafast dynamics; femtosecond near-field microscopy