Observation of Coexisting Dirac Bands and Moir\'e Flat Bands in Magic-Angle Twisted Trilayer Graphene

TL;DR

This study uses advanced spectroscopic techniques to reveal the coexistence of Dirac and moiré flat bands in magic-angle twisted trilayer graphene, providing insights into its electronic structure and superconducting properties.

Contribution

First direct measurement of the band structure in MATTG showing coexistence of Dirac and flat bands, aligning with theoretical predictions.

Findings

Coexistence of Dirac and moiré flat bands observed.

Band structure matches theoretical calculations.

Provides insights into superconductivity mechanisms.

Abstract

Moir\'e superlattices that consist of two or more layers of two-dimensional materials stacked together with a small twist angle have emerged as a tunable platform to realize various correlated and topological phases, such as Mott insulators, unconventional uperconductivity and quantum anomalous Hall effect. Recently, the magic-angle twisted trilayer graphene (MATTG) has shown both robust superconductivity similar to magic-angle twisted bilayer graphene (MATBG) and other unique properties, including the Pauli-limit violating and re-entrant superconductivity. These rich properties are deeply rooted in its electronic structure under the influence of distinct moir\'e potential and mirror symmetry. Here, combining nanometer-scale spatially resolved angle-resolved photoemission spectroscopy (nano-ARPES) and scanning tunneling microscopy/spectroscopy (STM/STS), we systematically measure the yet unexplored band structure of MATTG near charge neutrality. Our measurements reveal the coexistence of the distinct dispersive Dirac band with the emergent moir\'e flat band, showing nice agreement with the theoretical calculations. These results serve as a stepstone for further understanding of the unconventional superconductivity in MATTG.