Atomic-Scale Imaging of Lattice Relaxation and Topological Flat Bands in Helical Trilayer Graphene
Abstract
Helical trilayer graphene (HTG) has emerged as a highly tunable moire quantum material that hosts strong electronic correlations and nontrivial band topology. However, the atomic-scale lattice structure and local electronic properties have remained largely unexplored. Here we present a comprehensive real-space study of HTG using a combination of scanning near-field optical microscopy and low-temperature scanning tunneling microscopy. We directly image supermoire lattice relaxation, revealing large triangular domains separated by sharp domain walls, as well as stripe domains connected by smoothly varying boundaries. Atomic-scale spectroscopy uncovers flat bands with a honeycomb electronic texture and one-dimensional boundary states confined to domain walls. By systematically varying the twist angle, we identify a magic angle of approximately 1.9°, substantially larger than the 1.6 degree predicted by theory. Our results establish a direct microscopic link between lattice relaxation and flat bands in HTG.
Related
- Tunable topological narrow bands in twisted bilayer-trilayer graphene
- Phase-sensitive signatures of time-reversal-symmetry-breaking superconductivity in magic-angle twisted trilayer graphene
- Adiabatic confinement and number-theoretic spectra of massless Dirac fermions in twisted trilayer graphene
- Electrically Tunable Two-Component Exciton Condensate in a Coulomb-Coupled Graphene Trilayer
- Incipient superconductivity and tunable Chern insulators in twisted bilayer-trilayer graphene
BibTeX
@misc{jiang2026atomicscale,
title = {{Atomic-Scale Imaging of Lattice Relaxation and Topological Flat Bands in Helical Trilayer Graphene}},
author = {Shudan Jiang and Zonglin Li and Yu Gu and Liang Liu and Dandan Guan and Yaoyi Li and Hao Zheng and Canhua Liu and Kenji Watanabe and Takashi Taniguchi and Shengwei Jiang and Xiaoxue Liu and Zhiwen Shi and Guorui Chen and Jinfeng Jia and Tingxin Li and Can Li and Shiyong Wang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.39986},
eprint = {2609.39986},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.39986},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Atomic-Scale Imaging of Lattice Relaxation and Topological Flat Bands in Helical Trilayer Graphene
AU - Shudan Jiang
AU - Zonglin Li
AU - Yu Gu
AU - Liang Liu
AU - Dandan Guan
AU - Yaoyi Li
AU - Hao Zheng
AU - Canhua Liu
AU - Kenji Watanabe
AU - Takashi Taniguchi
AU - Shengwei Jiang
AU - Xiaoxue Liu
AU - Zhiwen Shi
AU - Guorui Chen
AU - Jinfeng Jia
AU - Tingxin Li
AU - Can Li
AU - Shiyong Wang
PY - 2026
DA - 2026/09/30
PB - arXiv
DO - 10.48550/arxiv.2609.39986
UR - https://arxiv.org/abs/2609.39986
AB - Helical trilayer graphene (HTG) has emerged as a highly tunable moire quantum material that hosts strong electronic correlations and nontrivial band topology. However, the atomic-scale lattice structure and local electronic properties have remained largely unexplored. Here we present a comprehensive real-space study of HTG using a combination of scanning near-field optical microscopy and low-temperature scanning tunneling microscopy. We directly image supermoire lattice relaxation, revealing large triangular domains separated by sharp domain walls, as well as stripe domains connected by smoothly varying boundaries. Atomic-scale spectroscopy uncovers flat bands with a honeycomb electronic texture and one-dimensional boundary states confined to domain walls. By systematically varying the twist angle, we identify a magic angle of approximately 1.9°, substantially larger than the 1.6 degree predicted by theory. Our results establish a direct microscopic link between lattice relaxation and flat bands in HTG.
ER -