Magneto-Moir\'e Excitons in Twisted Bilayer CrSBr

Abstract

Moir\'e superlattices in van der Waals materials have revolutionized the study of electronic and excitonic systems by creating periodic electrostatic potentials. Extending this concept to magnetic materials promises new pathways in merging spintronics with photonics. While moir\'e magnetism has been revealed with near-field probes and nonlinear optical techniques, the coupling of these magnetic textures to optical excitations - magneto-moir\'e excitons - remains unexplored. Here, we report the observation of magneto-moir\'e excitons in twisted bilayer CrSBr, correlated with moir\'e spin textures that emerge below a critical twist angle of ~2{\deg}. The nanoscale moir\'e spin texture imprints distinct signatures onto the optical spectrum, shifting the exciton energy via a periodic magnetic exchange field. First-principles calculations corroborate that these signatures arise from one-dimensional spin textures governed by the balance of exchange interactions and domain wall energy. Our results demonstrate that moir\'e magnetism can be used to engineer nanoscale excitonic energy landscapes, providing a new platform for magneto-optical sensing, quantum transduction, and control of non-collinear magnetism and topology through light.