Dirac Magic and Lifshitz Transitions in AA-Stacked Twisted Multilayer Graphene
Abstract
We uncover a new type of magic-angle phenomena when an AA-stacked graphene bilayer is twisted relative to another graphene system with band touching. In the simplest case this constitutes a trilayer system formed by an AA-stacked bilayer twisted relative to a single layer of graphene. We find multiple anisotropic Dirac cones coexisting in such twisted multilayer structures at certain angles, which we call "Dirac magic." We trace the origin of Dirac magic angles to the geometric structure of the twisted AA-bilayer Dirac cones relative to the other band-touching spectrum in the moir\'e reciprocal lattice. The anisotropy of the Dirac cones and a concomitant cascade of saddle points induce a series of topological Lifshitz transitions that can be tuned by the twist angle and perpendicular electric field. We discuss the possibility of direct observation of Dirac magic as well as its consequences for the correlated states of electrons in this moir\'e system.
Keywords
Cite
@article{arxiv.2107.10687,
title = {Dirac Magic and Lifshitz Transitions in AA-Stacked Twisted Multilayer Graphene},
author = {Yantao Li and Adam Eaton and H. A. Fertig and Babak Seradjeh},
journal= {arXiv preprint arXiv:2107.10687},
year = {2022}
}
Comments
4+{\epsilon} pages (exclusive of references), 4 figures, 7 supplemental figures