Dresden 2026 – scientific programme
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O: Fachverband Oberflächenphysik
O 38: Ultrafast electron dynamics at surface and interfaces II
O 38.4: Talk
Tuesday, March 10, 2026, 11:15–11:30, TRE/MATH
Ultrafast Formation and Annihilation of Strongly Bound Anisotropic Excitons in CrSBr — •Lawson T. Lloyd1, Tommaso Pincelli1,2, Mohamed A. Wahada1, Alessandro De Vita1,2, Ferdinand Menzel3, Kseniia Mosina4, Túlio H. L. G. Castro1, Alexander Neef1,2, Andreas V. Stier3, Nathan P. Wilson3, Zdeněk Sofer4, Jonathan J. Finley3, Martin Wolf1, Laurenz Rettig1, and Ralph Ernstorfer1,2 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany — 2Technische Universität Berlin, Berlin, Germany — 3Technische Universität München, Garching, Germany — 4University of Chemistry and Technology Prague, Prague, Czech Republic
Excitons dominate the optical response and determine the functionality of atomically thin semiconductors. In the van der Waals magnetic semiconductor CrSBr, strongly bound, anisotropic excitons couple to the underlying spin order, which could be leveraged in next-generation opto-spintronics. However, mechanisms of exciton formation, dissociation, and interaction with free carriers remain largely unexplored. Employing time- and angle-resolved photoemission spectroscopy, we probe the nature of the exciton in CrSBr by directly imaging the nonequilibrium electronic states, extracting fundamental properties of the excitonic wavefunction and revealing the driving mechanisms of exciton relaxation on ultrafast timescales. Notably, we observe an excitation-density-dependent interconversion between bound excitons and quasi-free carriers, indicating that many-body effects govern the excited state dynamics during the initial stages of relaxation.
Keywords: Excitons; 2D Materials; Ultrafast