Superconductivity in twisted multilayer graphene: a smoking gun in recent condensed matter physics

TL;DR

This paper reviews recent discoveries of superconductivity in twisted multilayer graphene, highlighting experimental control and the significance of these findings as a major breakthrough in condensed matter physics.

Contribution

It provides a comprehensive review of the experimental and theoretical developments in superconductivity in twisted multilayer graphene, emphasizing its role as a key discovery in the field.

Findings

Superconductivity observed in twisted bilayer graphene at magic angles

Gate-tunable Mott insulator states in graphene systems

Superconductivity also found in trilayer graphene

Abstract

In this article, we review the recent discoveries of exotic phenomena in graphene, especially superconductivity. It has been theoretically suggested for more than one decade that superconductivity may emerge in doped graphene-based materials. For single-layer graphene, there are theoretical predictions that spin-singlet $d+id$ pairing superconductivity is present when the filling is around the Dirac point. If the Fermi level is doped to the Van Hove singularity where the density of states diverges, then unconventional superconductivity with other pairing symmetry would appear. However, the experimental perspective was a bit disappointing. Despite extensive experimental efforts, superconductivity was not found in monolayer graphene. Recently, unconventional superconductivity was found in "magic-angle" twisted bilayer graphene. Superconductivity was also found in ABC stacked trilayer graphene and other systems. In this article, we review the unique properties of superconducting states in graphene, experimentally controlling the superconductivity in twisted bilayer graphene, as well as a gate-tunable Mott insulator, and the superconductivity in trilayer graphene. These discoveries have attracted the attention of a large number of physicists. The study of the electronic correlated states in twisted multilayer graphene serves as a smoking gun in recent condensed matter physics.