Spin-forbidden (ΔS≠0) multiplet excitations and their coupling to magnetic properties are of increasing importance for magneto-optical studies of correlated materials. Nonetheless, the mechanisms for optically brightening these transitions and their generality remain poorly understood. Here, we report magnetic circular dichroism (MCD) spectroscopy on the van der Waals ferromagnet (FM) CrI3. Previously unreported spin-forbidden (ΔS=1) A42g→E2g/T21g Cr3+ dd excitations are observed near the ligand-to-metal charge-transfer excitation threshold. The assignment of these excitations and their Cr3+ multiplet character is established through complementary Cr L3-edge resonant inelastic x-ray scattering measurements along with charge-transfer multiplet calculations and chemical trends in the chromium trihalide series (CrX3, X= Cl, Br, I). We utilize the high sensitivity of MCD spectroscopy to study the thickness-dependent optical response. The spin-forbidden excitations remain robust down to the monolayer limit, and we observe a significant magnetic-field dependence of the MCD spectrum across the antiferromagnetic-to-FM transition in few-layer samples. We preliminarily attribute this behavior to changes in the metal-ligand covalency with magnetic state. Our results clarify the magneto-optical response of CrI3 and identify covalency as a central mechanism for the brightening and field tunability of spin-forbidden multiplet excitations.
Spin-Forbidden Excitations in the Magneto-optical Spectra of CrI3 Tuned by Covalency / Occhialini, C.A., Nessi, L., Martins, L.G. p., Demir, A.K., Song, Q., Hasse, V., Shekhar, C., Felser, C., Watanabe, K., Taniguchi, T., Bisogni, V., Pelliciari, J., Comin, R.. - In: PHYSICAL REVIEW. X. - ISSN 2160-3308. - 15:3(2025), pp. 1-12. [10.1103/4km4-4rvn]
Spin-Forbidden Excitations in the Magneto-optical Spectra of CrI3 Tuned by Covalency
Pelliciari, Jonathan;
2025
Abstract
Spin-forbidden (ΔS≠0) multiplet excitations and their coupling to magnetic properties are of increasing importance for magneto-optical studies of correlated materials. Nonetheless, the mechanisms for optically brightening these transitions and their generality remain poorly understood. Here, we report magnetic circular dichroism (MCD) spectroscopy on the van der Waals ferromagnet (FM) CrI3. Previously unreported spin-forbidden (ΔS=1) A42g→E2g/T21g Cr3+ dd excitations are observed near the ligand-to-metal charge-transfer excitation threshold. The assignment of these excitations and their Cr3+ multiplet character is established through complementary Cr L3-edge resonant inelastic x-ray scattering measurements along with charge-transfer multiplet calculations and chemical trends in the chromium trihalide series (CrX3, X= Cl, Br, I). We utilize the high sensitivity of MCD spectroscopy to study the thickness-dependent optical response. The spin-forbidden excitations remain robust down to the monolayer limit, and we observe a significant magnetic-field dependence of the MCD spectrum across the antiferromagnetic-to-FM transition in few-layer samples. We preliminarily attribute this behavior to changes in the metal-ligand covalency with magnetic state. Our results clarify the magneto-optical response of CrI3 and identify covalency as a central mechanism for the brightening and field tunability of spin-forbidden multiplet excitations.
Pubblicazioni consigliate
I metadati presenti in IRIS UNIMORE sono rilasciati con licenza Creative Commons CC0 1.0 Universal, mentre i file delle pubblicazioni sono rilasciati con licenza Attribuzione 4.0 Internazionale (CC BY 4.0), salvo diversa indicazione.
In caso di violazione di copyright, contattare Supporto Iris
