Topological domain-wall states from Umklapp scattering in twisted bilayer graphene

Juncheng Li; Cong Chen; Wang Yao

doi:10.1021/acs.nanolett.5c04006

paper

Topological domain-wall states from Umklapp scattering in twisted bilayer graphene

arXiv:2508.03761 · doi:10.1021/acs.nanolett.5c04006

Abstract

Twistronics, harnessing interlayer rotation to tailor electronic states in van der Waals materials, has predominantly focused on small-angle regime. Here, we unveil the pivotal role of intervalley Umklapp scattering in large-angle twisted bilayer graphene, which governs low-energy physics and drives unconventional band topology. By constructing symmetry-constrained effective $k \cdot p$ models for $\pm 21. 8^{\circ}$ -twisted bilayers, we demonstrate how structural chirality imprints distinct electronic responses. The $D_{6}$ configuration exhibits a gapped spectrum with chiral interlayer coupling, while $D_{3}$ symmetric stacking configuration displays semimetallic behavior. Crucially, chirality inversion creates topological domain-wall states, which manifest as counterpropagating pseudospin modes at interfaces between oppositely twisted regions. These states, absent in untwisted bilayers, emerge from a Jackiw-Rebbi-like mechanism tied to chirality reversal. Atomistic simulations confirm these topological states and demonstrate their robustness against symmetry-breaking perturbations. The interplay between twist-induced chirality and topology opens new pathways for engineering domain-wall states in twisted materials.

arXiv comment8 pages, 7 figures

References in corpus (36)

Cited by in corpus (1)

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