Microscopic origin of the intermediate exciton resonance

Establish the microscopic origin of the intermediate exciton resonance $X_{inter}$ observed in multilayer CrSBr when an inner layer has oppositely aligned neighboring magnetizations.

Background

The authors identify an intermediate optical resonance, XinterX_{inter}, in four- and five-layer CrSBr during field-driven transitions from the fully ferromagnetic to antiferromagnetic states. Within their simplified model, this resonance arises from an inner layer whose two neighboring layers have opposite magnetization directions. However, the model establishes the magnetic configuration associated with the resonance without explaining its microscopic excitonic origin, leaving open the underlying electronic, magnetic, and dielectric mechanism responsible for XinterX_{inter}.

References

The microscopic origin of $X_{inter}$ remains to be established.

— Excitonic fingerprints of magnetic configurations and switching in multilayer CrSBr  (2608.24216 - Krelle et al., 25 Aug 2026) in Results and Discussion, paragraph following Fig. 4 discussion

We therefore cannot unambiguously identify a surface exciton associated with the higher-energy resonance. We suggest measurements at high magnetic fields as in to clarify the origin of this resonance in the context of a surface confined exciton.

— Excitonic fingerprints of magnetic configurations and switching in multilayer CrSBr  (2608.24216 - Krelle et al., 25 Aug 2026) in Results and Discussion, paragraph beginning “The higher-energy exciton shares several characteristics with $X_b$”

Note that the slight temperature dependence of SHG above $T_{\rm{C}$ is not fully understood yet. As this is not the main focus of our current paper, we postpone a more detailed investigation to future work.

— Probing temperature dependent non-radiative decay channels in CrSBr with nonlinear optics  (2609.31163 - Dan et al., 25 Sep 2026) in Section 3, “Temperature dependence of the PL and NLO response”