Activated Migration of Localized Ligand-Field Excitons in Atomically Thin CrCl3
Abstract
Two-dimensional crystals with densely packed atoms exhibit a range of emerging properties, particularly a wide variety of excitonic behaviors. Thickness-variable layered chromium trihalides with finite surface recombination sites provide an ideal system for understanding how excitons confined in octahedral ligand fields migrate on nanometer length scales, a regime that defies conventional transport probes. In this work, we demonstrate that Cr3+-derived photoluminescence in CrCl3 is spectrally thickness-independent, but its relaxation dynamics are strongly sensitive to thickness and temperature, thereby indicating significant activated migration. A diffusion-coupled surface recombination model reveals an effective out-of-plane diffusivity of 4.5 x 10-6 cm2/s for the ligand-field excitons and a diffusion activation energy of 130 meV. The latter is comparable to the reorganization energy independently estimated from optical Stokes shifts, suggesting that exciton transport is coupled to local lattice relaxation. Furthermore, we show that the relaxation dynamics can be systematically tuned by either enhancing or suppressing surface recombination through controlled surface reactions or encapsulation. This work not only reveals the nanoscopic transport of localized ligand-field excitons but also establishes a spectroscopic transport probe applicable to various 2D materials.
Versions
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BibTeX
@misc{kim2026activated,
title = {{Activated Migration of Localized Ligand-Field Excitons in Atomically Thin CrCl3}},
author = {Hyesun Kim and Renlong Liu and Sangho Yoon and Hyunjong Lim and Takashi Taniguchi and Kenji Watanabe and Jonghwan Kim and Changgu Lee and Sunmin Ryu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.16702},
eprint = {2606.16702},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.16702},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Activated Migration of Localized Ligand-Field Excitons in Atomically Thin CrCl3
AU - Hyesun Kim
AU - Renlong Liu
AU - Sangho Yoon
AU - Hyunjong Lim
AU - Takashi Taniguchi
AU - Kenji Watanabe
AU - Jonghwan Kim
AU - Changgu Lee
AU - Sunmin Ryu
PY - 2026
DA - 2026/09/04
PB - arXiv
DO - 10.48550/arxiv.2606.16702
UR - https://arxiv.org/abs/2606.16702
AB - Two-dimensional crystals with densely packed atoms exhibit a range of emerging properties, particularly a wide variety of excitonic behaviors. Thickness-variable layered chromium trihalides with finite surface recombination sites provide an ideal system for understanding how excitons confined in octahedral ligand fields migrate on nanometer length scales, a regime that defies conventional transport probes. In this work, we demonstrate that Cr3+-derived photoluminescence in CrCl3 is spectrally thickness-independent, but its relaxation dynamics are strongly sensitive to thickness and temperature, thereby indicating significant activated migration. A diffusion-coupled surface recombination model reveals an effective out-of-plane diffusivity of 4.5 x 10-6 cm2/s for the ligand-field excitons and a diffusion activation energy of 130 meV. The latter is comparable to the reorganization energy independently estimated from optical Stokes shifts, suggesting that exciton transport is coupled to local lattice relaxation. Furthermore, we show that the relaxation dynamics can be systematically tuned by either enhancing or suppressing surface recombination through controlled surface reactions or encapsulation. This work not only reveals the nanoscopic transport of localized ligand-field excitons but also establishes a spectroscopic transport probe applicable to various 2D materials.
ER -