Challenges and opportunities in proximity-driven exciton-spin engineering in van der Waals heterostructures

van der Waals heterostructures consisting of transition metal dichalcogenides (TMDs) and two-dimensional (2D) magnets offer a versatile platform to study the coexistence and transformation of different excitons. By focusing on TMD WSe 2 and 2D magnetic CrI 3 , as a bilayer WSe 2 /CrI 3 and a trilayer CrI 3 /WSe 2 /CrI 3 , we provide their description using a parameter-free, high-fidelity many-body perturbation theory. This ab initio approach allows us to elucidate the character of magnetic Frenkel excitons in CrI 3 and how the nonmagnetic Wannier-Mott excitons in WSe 2 are modified by the proximity of CrI 3 . We reveal novel proximity-induced interlayer excitons in these heterostructures. In contrast to the sensitivity of proximity-induced modifications of excitons in WSe 2 , which depend on interfacial details, we find a systematic appearance of interlayer magnetic excitons across the stacking configurations considered here; their energy remains nearly unchanged across the stacking variants ( ~ 1.98–1.99 eV), while their oscillator strengths and interlayer decompositions are stacking dependent. These findings suggest unexplored opportunities for information transduction using magnetic excitons and integrating photonics, electronics, and spintronics in proximitized materials.