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HL: Fachverband Halbleiterphysik

HL 60: Focus Session: Physics of the van der Waals Magnetic Semiconductor CrSBr II (joint session HL/MA)

HL 60.6: Vortrag

Freitag, 21. März 2025, 12:00–12:15, H17

Internal structure and ultrafast dynamics of quasi- 1D excitons controlled by magnetic order — •N. Nilforoushan¹, M. Liebich¹, M. Florian², F. Mooshammer^{1, 3}, A. D. Koulouklidis^{1, 3}, L. Wittmann¹, K. Mosina⁴, Z. Sofer⁴, F. Dirnberger⁵, M. Kira², and R. Huber^{1, 3} — ¹Dept. of Physics, University of Regensburg, Germany — ²Dept. of Electrical Engineering and Computer Science, University of Michigan, USA — ³RUN, University of Regensburg, Germany — ⁴Dept. of Inorganic Chemistry, University of Chemistry and Technology Prague, Czech Republic — ⁵Dept. of Physics, Technical University of Munich, Germany

In van der Waals (vdW) layered crystals, Coulomb correlations are often tuned by structural engineering, giving rise to emergent phenomena such as tightly bound excitons and exotic electronic and magnetic phases. Magnetic vdW materials offer a unique platform for in situ control of Coulomb correlations enabled by their intrinsic magnetic order. Here, we present quantitative experiment-theory proof that excitonic correlations can be tailored through spin order in the vdW magnet CrSBr. By probing internal transitions of excitons with phase-locked mid-infrared pulses, we reveal their binding energy and strong anisotropy of their quasi-1D orbitals resulting in significant fine-structure splitting. We switch excitons from monolayer-localized to interlayer-delocalized species by pushing the system from the antiferromagnetic to the paramagnetic phase. The exciton's ultrafast dynamics further support this scenario. In future applications, excitons may be interfaced with spintronics enabling on-demand phase transitions.

Keywords: 2D magnets; Ultrafast dynamics; excitons; Time-domain spectroscopy