Twistronics in graphene-based van der Waals structures

TL;DR

This paper reviews recent experimental advances in the strongly correlated electronic phenomena observed in magic-angle twisted bilayer and multilayer graphene structures, highlighting the role of moire superlattices and flat bands.

Contribution

It provides a comprehensive overview of experimental progress in understanding correlated phases in twisted graphene systems near the magic angle.

Findings

Observation of flat bands at the magic angle (~1.1°) in TBG

Experimental evidence of correlated insulating and superconducting states

Insights into the role of moire superlattices in electronic property modification

Abstract

The electronic properties of van der Waals (vdW) structures can be substantially modified by the moire superlattice potential, which strongly depends on the twist angle among the compounds. In twisted bilayer graphene (TBG), two low-energy Van Hove singularities (VHSs) move closer with decreasing twist angles and finally become highly non-dispersive flat bands at the magic angle (~ 1.1 degree). When the Fermi level lies within the flat bands of the TBG near the magic angle, Coulomb interaction is supposed to exceed the kinetic energy of the electrons, which can drive the system into various strongly correlated phases. Moreover, the strongly correlated states of flat bands are also realized in other graphene-based vdW structures with an interlayer twist. In this article, we mainly review the recent experimental advances on the strongly correlated physics of the magic-angle TBG (MATBG) and the small-angle twisted multilayer graphene. Lastly we will give out a perspective of this field.