biostudies-literatureSmiertka MDOE | Advanced Research Projects Agency - Energy (Advanced Research Projects Agency - Energy - U.S. Department of Energy)1777https://www.ebi.ac.uk/biostudies/studies/S-EPMC12916971biostudies-literatureUnknown17(1)Excitons in recently discovered two-dimensional magnetic semiconductors have emerged as a promising vehicle for optoelectronic and spin-photonic applications. To exploit novel possibilities magnetic degrees of freedom offer, insight into the interplay of magnetism, lattice and optical excitations becomes essential. We consider Chromium Sulphur Bromide, which has two kinds of excitons, X_B at 1.8 eV and X_A at 1.38 eV. Here we show, through a combination of many body perturbation theory and experiment, that X_B is an order of magnitude more sensitive to magnetic and lattice perturbations than X_A. We trace the difference to the latter being localised (Frenkel-like), while the former is delocalised (Wannier-Mott-like) - a coexistence rarely seen in twoNature communicationsDistinct magneto-optical response of Frenkel and Wannier excitons in CrSBr.PMC12916971DE-AC02-05CH11231DE-AC36-08GO28308Dirnberger FSofer ZMosina KPosmyk KPeksa PDyksik Mvan Schilfgaarde MAcharya SPashov DBaranowski MPlochocka PSmiertka MRygala MfalseDistinct magneto-optical response of Frenkel and Wannier excitons in CrSBr.Excitons in recently discovered two-dimensional magnetic semiconductors have emerged as a promising vehicle for optoelectronic and spin-photonic applications. To exploit novel possibilities magnetic degrees of freedom offer, insight into the interplay of magnetism, lattice and optical excitations becomes essential. We consider Chromium Sulphur Bromide, which has two kinds of excitons, X_B at 1.8 eV and X_A at 1.38 eV. Here we show, through a combination of many body perturbation theory and experiment, that X_B is an order of magnitude more sensitive to magnetic and lattice perturbations than X_A. We trace the difference to the latter being localised (Frenkel-like), while the former is delocalised (Wannier-Mott-like) - a coexistence rarely seen in two2026-01-01T00:00:00Z2026 Jan2026-07-16T09:55:36.336Z2026-07-09T10:49:23.364ZS-EPMC129169714154785810.1038/s41467-026-68482-5