A theoretical and experimental study of spin waves in CrSBr heterostructures

We measure and model spin waves in heterojunctions of the two-dimensional magnet CrSBr with other 2D materials and organic molecules, combining experiments, density functional theory (DFT), and quantum field theory (QFT) modeling. We investigate the influence of different heterojunctions, namely a 2D magnet, a transition metal dichalcogenide, and an organic on exchange interactions within CrSBr. Experimentally, we investigate exciton dynamics through photoluminescence measurements (PL) under a tunable magnetic field and probe magnon properties via time- and spatially-resolved pump–probe spectroscopy, enabling direct comparison of spin-wave propagation in pristine CrSBr and its heterostructures. We construct select heterostructures and study their steady-state and time-resolved optical response as a function of excitation wavelength, magnetic field and temperature, revealing how interfacial coupling modifies exciton–magnon interactions. To interpret these results, DFT-derived lattice geometries and exchange couplings are incorporated into a QFT-based model of spin-wave dispersion in van der Waals heterostructures.