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Updated: Jan 19, 2026

Spectral and Angle-Resolved Magneto-Optical Characterization of Photonic Nanostructures
Published on: November 21, 2019
Distinct magneto-optical response of Frenkel and Wannier excitons in CrSBr
Maciej Śmiertka1, Michał Rygała2, Katarzyna Posmyk1,2
1Department of Experimental Physics, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wroclaw, Poland.
Abstract:
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, XB at 1.8 eV and XA at 1.38 eV. Here we show, through a combination of many body perturbation theory and experiment, that XB is an order of magnitude more sensitive to magnetic and lattice perturbations than XA. We trace the difference to the latter being localised (Frenkel-like), while the former is delocalised (Wannier-Mott-like) - a coexistence rarely seen in two-dimensional materials. This finding is supported by the strong temperature and magnetic field (up to 85 Tesla) dependent shifts in optical response for XB (much smaller for XA), and we show it is related to XB's tendency for delocalisation (in-plane and out-of-plane) and enhanced coupling with Ag phonon modes.
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