Graphene Bilayers with a Twist

TL;DR

This paper reviews the unique electronic phenomena observed in magic-angle twisted bilayer graphene, emphasizing its transition to a strongly correlated electron system with diverse quantum states and potential for novel quantum materials.

Contribution

It provides a comprehensive overview of recent experimental findings and open questions in the study of magic-angle twisted bilayer graphene.

Findings

Observation of superconductivity near magic angle

Presence of interaction-induced insulating states

Emergence of magnetism and electronic nematicity

Abstract

Near a magic twist angle, bilayer graphene transforms from a weakly correlated Fermi liquid to a strongly correlated two-dimensional electron system with properties that are extraordinarily sensitive to carrier density and to controllable environmental factors such as the proximity of nearby gates and twist-angle variation. Among other phenomena magic-angle twisted bilayer graphene hosts superconductivity, interaction induced insulating states, magnetism, electronic nematicity, linear-in-T low-temperature resistivity, and quantized anomalous Hall states. We highlight some key research results in this field, point to important questions that remain open, and comment on the place of magic angle twisted bilayer graphene in the strongly correlated quantum matter world.