Berry curvature of low-energy excitons in rhombohedral graphene
File(s)
Published version
Author(s)
Davenport, Henry
Schindler, Frank
Knolle, Johannes
Type
Journal Article
Abstract
We investigate low-energy excitons in rhombohedral pentalayer graphene encapsulated by hexagonal boron
nitride (hBN/R5G/hBN), focusing on the regime at the experimental twist angle θ = 0.77◦ and with an applied
electric field. We introduce a new low-energy two-band model of rhombohedral graphene that captures the band structure more accurately than previous models while keeping the number of parameters low. Using this model, we show that the centres of the exciton Wannier functions are displaced from the moiré unit cell origin by a quantized amount—they are instead localized at C3-symmetric points on the boundary. We also find that the exciton shift is electrically tunable: by varying the electric field strength, the exciton Wannier center can be exchanged between inequivalent corners of the moiré unit cell. Our results suggest the possibility of detecting excitonic corner or edge modes, as well as novel excitonic crystal defect responses in hBN/R5G/hBN. Lastly, we find that the excitons in hBN/R5G/hBN inherit excitonic Berry curvature from the underlying electronic bands, enriching their semiclassical transport properties. Our results position rhombohedral graphene as a compelling tunable platform for probing exciton topology in moiré materials.
nitride (hBN/R5G/hBN), focusing on the regime at the experimental twist angle θ = 0.77◦ and with an applied
electric field. We introduce a new low-energy two-band model of rhombohedral graphene that captures the band structure more accurately than previous models while keeping the number of parameters low. Using this model, we show that the centres of the exciton Wannier functions are displaced from the moiré unit cell origin by a quantized amount—they are instead localized at C3-symmetric points on the boundary. We also find that the exciton shift is electrically tunable: by varying the electric field strength, the exciton Wannier center can be exchanged between inequivalent corners of the moiré unit cell. Our results suggest the possibility of detecting excitonic corner or edge modes, as well as novel excitonic crystal defect responses in hBN/R5G/hBN. Lastly, we find that the excitons in hBN/R5G/hBN inherit excitonic Berry curvature from the underlying electronic bands, enriching their semiclassical transport properties. Our results position rhombohedral graphene as a compelling tunable platform for probing exciton topology in moiré materials.
Date Issued
2026-03-02
Date Acceptance
2026-01-07
Citation
Physical Review B, 2026, 113 (11)
ISSN
2469-9950
Publisher
American Physical Society (APS)
Journal / Book Title
Physical Review B
Volume
113
Issue
11
Copyright Statement
Published by the American Physical Society Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
License URL
Publication Status
Published
Article Number
115102
Date Publish Online
2026-03-02