Probing temperature dependent non-radiative decay channels in CrSBr with nonlinear optics

Abstract: Among the recently discovered layered magnetic materials, the antiferromagnet CrSBr has attracted considerable interest thanks to its stability, quasi-one-dimensional crystal structure, and direct near-infrared band gap. These properties make it a suitable platform for combined electrical, magnetic, and optical measurements, and thus for studying exciton dynamics and transport across different magnetic phases. In this work, we investigate the optical response of CrSBr across its paramagnetic and antiferromagnetic phases by combining nonlinear optical spectroscopy, including second-harmonic generation, third-harmonic generation, and two-photon photoluminescence, with linear photoluminescence measurements. The observation of a clear difference in the temperature dependence of third-harmonic generation and photoluminescence intensities allows us to identify the onset of non-radiative recombination channels in the antiferromagnetic phase.