Interplay of Kekulé order, flat bands and electron-phonon coupling in graphene
Abstract
The Kekulé order in graphene is known to coexist with both an extended flat band near the van Hove singularity (VHS) and enhanced electron-phonon coupling. However, the microscopic origin of this interplay is still not fully understood. Here, this behavior is traced to the Kekulé-induced bond distortion and the resulting redistribution of electronic delocalization. In this picture, the conduction band below the VHS is observed to flatten with increasing Kekulé order, extending its intrinsically weakly dispersive region around the saddle point over a broader momentum range. In parallel, the VHS and dimensionless electron-phonon coupling exhibit approximately quadratic upward responses. The resulting enhancement of the electron-phonon coupling is found to be predominantly governed by the increasing density of states, with the effective deformation potential remaining weakly affected by the distortion. As such, the obtained results are consistent with previous theoretical and experimental studies, while also pointing toward the narrowing of the conduction band and a possible departure of the electron-phonon coupling from the conventional adiabatic regime. Altogether, they highlight the potential of controlled Kekulé ordering for engineering emergent correlated quantum phases in graphene.
Related
- Real-space understanding of electron-phonon coupling in superconducting hydrides
- Electron--phonon cooling noise in monolayer and bilayer graphene
- Stability, Collective Modes, and Quasiparticle-Phonon Coupling of Metallic Wigner Crystals in Rhombohedral Graphene
- Spectroscopic signatures of mode-selective electron-phonon coupling in transient reflectivity change on charge-density-wave TiSe2
- Helicity-Selective Electron-Phonon Coupling Between PT-Partner States in 2H-bilayer MoS2
BibTeX
@misc{szczȩsniak2026interplay,
title = {{Interplay of Kekulé order, flat bands and electron-phonon coupling in graphene}},
author = {Dominik Szczȩśniak},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2609.11711},
eprint = {2609.11711},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.11711},
}
RIS
TY - UNPB
TI - Interplay of Kekulé order, flat bands and electron-phonon coupling in graphene
AU - Dominik Szczȩśniak
PY - 2026
DA - 2026/10/09
PB - arXiv
DO - 10.48550/arxiv.2609.11711
UR - https://arxiv.org/abs/2609.11711
AB - The Kekulé order in graphene is known to coexist with both an extended flat band near the van Hove singularity (VHS) and enhanced electron-phonon coupling. However, the microscopic origin of this interplay is still not fully understood. Here, this behavior is traced to the Kekulé-induced bond distortion and the resulting redistribution of electronic delocalization. In this picture, the conduction band below the VHS is observed to flatten with increasing Kekulé order, extending its intrinsically weakly dispersive region around the saddle point over a broader momentum range. In parallel, the VHS and dimensionless electron-phonon coupling exhibit approximately quadratic upward responses. The resulting enhancement of the electron-phonon coupling is found to be predominantly governed by the increasing density of states, with the effective deformation potential remaining weakly affected by the distortion. As such, the obtained results are consistent with previous theoretical and experimental studies, while also pointing toward the narrowing of the conduction band and a possible departure of the electron-phonon coupling from the conventional adiabatic regime. Altogether, they highlight the potential of controlled Kekulé ordering for engineering emergent correlated quantum phases in graphene.
ER -