Excitons probe intrinsic flat band Mottness in a van der Waals heterostructure
Abstract
Excitons provide a sensitive optical probe of electronic correlations in nearby two-dimensional materials, yet their coupling to intrinsic flat-band Mott systems remains largely unexplored. Here we combine gate-tunable optical spectroscopy with first-principles calculations to study monolayer WSe2 in direct contact with the van der Waals Mott insulator Nb3Cl8. The gate evolution of WSe2 excitonic resonances reveals signatures of a correlation-reconstructed Mott gap in Nb3Cl8 that is absent from the single-particle band picture. In the electron-doped regime, the WSe2 2s Rydberg exciton undergoes a multistage evolution and develops into interlayer attractive and repulsive polaron branches, showing that a Rydberg exciton can be dressed by strongly correlated flat-band electrons in an adjacent Mott layer. Under an out-of-plane magnetic field, spin-polarized Nb3Cl8 states further induce valley-selective exciton coupling, producing a strongly enhanced circular polarization of the WSe2 exciton emission. These results extend exciton-based sensing and exciton-polaron physics to intrinsic flat-band Mott materials, providing an optical route to probe and engineer correlation-driven interfacial quasiparticles.
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BibTeX
@misc{huang2026excitons,
title = {{Excitons probe intrinsic flat band Mottness in a van der Waals heterostructure}},
author = {Xinyue Huang and Xintong Tan and Haowei Chen and Yingzhou Huang and Yushen Zhou and Yuchen Gao and Zhijie Ma and Chengxin Xiao and Kenji Watanabe and Takashi Taniguchi and Jianpeng Liu and Zuxin Chen and Youguo Shi and Wang Yao and Yu Ye},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.07101},
eprint = {2609.07101},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.07101},
note = {CC0},
}
RIS
TY - UNPB
TI - Excitons probe intrinsic flat band Mottness in a van der Waals heterostructure
AU - Xinyue Huang
AU - Xintong Tan
AU - Haowei Chen
AU - Yingzhou Huang
AU - Yushen Zhou
AU - Yuchen Gao
AU - Zhijie Ma
AU - Chengxin Xiao
AU - Kenji Watanabe
AU - Takashi Taniguchi
AU - Jianpeng Liu
AU - Zuxin Chen
AU - Youguo Shi
AU - Wang Yao
AU - Yu Ye
PY - 2026
DA - 2026/09/07
PB - arXiv
DO - 10.48550/arxiv.2609.07101
UR - https://arxiv.org/abs/2609.07101
AB - Excitons provide a sensitive optical probe of electronic correlations in nearby two-dimensional materials, yet their coupling to intrinsic flat-band Mott systems remains largely unexplored. Here we combine gate-tunable optical spectroscopy with first-principles calculations to study monolayer WSe_2 in direct contact with the van der Waals Mott insulator Nb_3Cl_8. The gate evolution of WSe_2 excitonic resonances reveals signatures of a correlation-reconstructed Mott gap in Nb_3Cl_8 that is absent from the single-particle band picture. In the electron-doped regime, the WSe_2 2s Rydberg exciton undergoes a multistage evolution and develops into interlayer attractive and repulsive polaron branches, showing that a Rydberg exciton can be dressed by strongly correlated flat-band electrons in an adjacent Mott layer. Under an out-of-plane magnetic field, spin-polarized Nb_3Cl_8 states further induce valley-selective exciton coupling, producing a strongly enhanced circular polarization of the WSe_2 exciton emission. These results extend exciton-based sensing and exciton-polaron physics to intrinsic flat-band Mott materials, providing an optical route to probe and engineer correlation-driven interfacial quasiparticles.
ER -