Correlating Electronic Structure and Photoluminescence in CrSBr: Insights from XAS, RIXS, and XEOL

Magnetic van der Waals (vdW) materials have attracted significant attention over the last decade. Owing to their quasi-2D behavior, the possibility to control the number of layers and to construct vertical heterostructures, these systems offer vast possibilities to explore new physics and design advanced spintronic devices. In this context, Cr-based vdW magnets display a great potential thanks to their optical and magnetic characteristics.

We focus here on the vdW antiferromagnet CrSBr. Its stability in air, together with its unique magnetoelectric coupling properties, makes this system one of the most promising materials for future optoelectronic applications. Indeed, it hosts at least two optically active excitons strongly coupled to the magnetic state of the system. They are at the origin of a strong photoluminescence (PL), which is tunable in energy and shape by: strain, number of layers, and by driving the system from an anti-ferromagnetic to a ferromagnetic phase upon the application of a relatively weak magnetic field of about 0.35 T.

To gain deeper insight into the mechanisms governing the observed PL and to relate it with the electronic structure of CrSBr, we correlate X-ray Absorption Spectroscopy (XAS), Resonant Inelastic X-ray Scattering (RIXS), and X-ray Excited Optical Luminescence (XEOL), acquired in one single experiment and therefore in same experimental conditions. Our measurements reveal significant linear dichroism, along with signatures of characteristic Cr³⁺ d-d transitions, which we attempt to model using crystal field calculations. To further explore the relationship between magnetic properties and PL behavior, we also present the evolution of both RIXS and PL under an applied magnetic field. This study highlights the benefits of combining excitation and recombination spectroscopy techniques.