Electronic Structure of Single-Twist Trilayer Graphene

TL;DR

This paper investigates the electronic properties of trilayer graphene with a small twist angle, revealing how stacking arrangements influence the emergence of correlated states and identifying promising configurations for magnetism and superconductivity.

Contribution

It derives moiré band models for twisted trilayer graphene with various stackings, highlighting the dependence of electronic structure on stacking and twist layer, and proposing ABA stacking with middle-layer twist as a promising system.

Findings

Electronic structure varies strongly with stacking and twist layer.

ABA stacking with middle-layer twist shows potential for magnetism and superconductivity.

Identification of bands near the Fermi level suitable for correlated phenomena.

Abstract

Small-twist-angle bilayer graphene supports strongly correlated insulating states and superconductivity. Twisted few-layer graphene systems are likely to open up new directions for strong correlation physics in moir\'e superlattices. We derive and study moir\'e band models that describe the electronic structure of graphene trilayers in which one of the three layers is twisted by a small angle relative to perfect AAA, ABA, or ABC stacking arrangements. We find that the electronic structure depends very strongly on the starting stackings arrangement and on which layer is twisted. We identify ABA stacking with a middle-layer twist as a promising system for itinerant electron magnetism or even more robust superconductivity, because it exhibits both large and small velocity bands at energies near the Fermi level.