RSS icon
Twitter icon
Facebook icon
Vimeo icon
YouTube icon

Hofstadter butterfly and Floquet topological insulators in minimally twisted bilayer graphene

TitleHofstadter butterfly and Floquet topological insulators in minimally twisted bilayer graphene
Publication TypeJournal Article
Year of Publication2020
AuthorsY-Z. Chou, F. Wu, and S. Das Sarma
JournalPhys. Rev. Res.
Volume2
Date Publishedaug
Abstract

We theoretically study the Hofstadter butterfly of a triangular network model in minimally twisted bilayer graphene. The band structure manifests periodicity in energy, mimicking that of Floquet systems. The butterfly diagrams provide fingerprints of the model parameters and reveal the hidden band topology. In a strong magnetic field, we establish that minimally twisted bilayer graphene realizes low-energy Floquet topological insulators (FTIs) carrying zero Chern number, while hosting chiral edge states in bulk gaps. We identify the FTIs by analyzing the nontrivial spectral flow in the Hofstadter butterfly, and by explicitly computing the chiral edge states. Our theory paves the way for an effective practical realization of FTIs in equilibrium solid-state systems.

DOI10.1103/PhysRevResearch.2.033271