CrSBr, a van der Waals material, stands out as an air-stable magnetic semiconductor with appealing intrinsic properties such as crystalline anisotropy, quasi-1D electronic characteristics, layer-dependent antiferromagnetism, and non-linear optical effects. We investigate the differences between the absorption and emission spectra, focusing on the origin of the emission peak near 1.7 eV observed in the photoluminescence spectrum of CrSBr. Our findings are corroborated by excitation energy-dependent Raman experiments. Additionally, we explore the anti-Stokes Raman spectra and observe an anomalously high anti-Stokes-to-Stokes intensity ratio of up to 0.8, which varies significantly with excitation laser power and crystallographic orientation relative to the polarization of the scattered light, highlighting the unique vibrational and electronic interactions in CrSBr. Lastly, we examine stimulated Raman scattering and calculate the Raman gain in CrSBr, which attains a value of 1 × 108 cm GW-1, nearly four orders of magnitude higher than that of previously studied three-dimensional systems.

Department of Biophysics Chemical and Macromolecular Physics Faculty of Mathematics and Physics Charles University Ke Karlovu 3 121 16 Prague Czech Republic

Department of Inorganic Chemistry University of Chemistry and Technology Prague Technická 5 166 28 Prague Czech Republic

Institut für Physik Freie Universität Berlin Arnimallee 14 14195 Berlin Germany

J Heyrovský Institute of Physical Chemistry Czech Academy of Sciences Dolejškova 2155 3 182 23 Prague Czech Republic

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Magnetic Correlation Spectroscopy in CrSBr